Carbon dioxide emitted from existing coal-fired power plants is a major environmental concern due to possible links to global climate change. In this study, we expand upon previous work focused on aminosilane-functionalized polymeric hollow-fiber sorbents by introducing a new class of polyethyleneimine (PEI)-functionalized polymeric hollow-fiber sorbents for post-combustion carbon dioxide capture. Different molecular weight PEIs (M_n≈600, 1800, 10 000, and 60 000) were studied as functional groups on polyamide imide (PAI, Torlon) hollow fibers. This imide ring-opening modification introduces two amide functional groups and was confirmed by FTIR attenuated total reflectance spectroscopy. The carbon dioxide equilibrium sorption capacities of PEI-functionalized Torlon materials were characterized by using both pressure decay and gravimetric sorption methods. For equivalent PEI concentrations, PAI functionalized with lower molecular weight PEI exhibited higher carbon dioxide capacities. The effect of water in the ring-opening reaction was also studied. Up to a critical value, water in the reaction mixture enhanced the degree of functionalization of PEI to Torlon and resulted in higher carbon dioxide uptake within the functionalized material. Above the critical value, roughly 15 % w/w water, the fiber morphology was lost and the fiber was soluble in the solvent. PEI-functionalized (M_n≈600) PAI under optimal reaction conditions was observed to have the highest CO₂ uptake: 4.9 g CO₂ per 100 g of polymer (1.1 mmol g⁻¹) at 0.1 bar and 35 °C with dry 10 % CO₂/90 % N₂ feed for thermogravimetric analysis. By using water-saturated feeds (10 % CO₂/90 % N₂ dry basis), CO₂ sorption was observed to increase to 6.0 g CO₂ per 100 g of sorbent (1.4 mmol g⁻¹). This material also demonstrated stability in cyclic adsorption–desorption operations, even under wet conditions at which some highly effective sorbents tend to lose performance. Thus, PEI-functionalized PAI fibers can be considered as promising material for post-combustion CO₂ capture.

Sucked in! Polyethyleneimine (PEI)-functionalized polymeric hollow-fiber sorbents for post-combustion carbon dioxide capture are described. Different molecular weight PEIs are studied as functional groups on polyamide imide (PAI) hollow fibers. For equivalent PEI concentrations, PAI functionalized with lower molecular weight PEI exhibit higher CO₂ capacities (see picture).

The high activity and selectivity of zeolites in the cyclisation of unsaturated alcohols is reported for the first time; the details of a reaction mechanism based on quantum chemical calculations are also provided. The high efficiency of zeolites MFI, BEA and FAU in the cyclisation of unsaturated alcohols (cis-decen-1-ol, 6-methylhept-5-en-2-ol and 2-allylphenol) to afford oxygen-containing heterocyclic rings is demonstrated. The best catalytic performance is found for zeolites with the optimum concentration of Brønsted acid sites (ca. 0.2 mmol g⁻¹) and the minimum number of Lewis acid sites. It is proposed that the efficiency of the catalysts is reduced by the existence of the so-called dual site, at which a molecule of unsaturated alcohol can simultaneously interact with two acid sites (an OH group with one and the double bond with the other Brønsted site), which increases the interaction strength. The formation of such adsorption complexes leads to a decrease in the catalyst activity because of (i) an increase in the reaction barrier, (ii) an unfavourable conformation and (iii) diffusion limitations. A new procedure for the preparation of tetrahydrofurans and pyrans over zeolite catalysts provides important oxygen-containing heterocycles with numerous applications.

The zeolite fantastic: The high efficiency of zeolites MFI, BEA and FAU in the cyclisation of unsaturated alcohols to afford oxygen-containing heterocyclic rings is demonstrated. It is proposed that the efficiency of the catalysts depends on the existence of the so-called dual site, at which a molecule of an unsaturated alcohol can simultaneously interact with two acid sites.

The development of new and improved processes for the synthesis of bio-based chemicals is one of the scientific challenges of our time. These new discoveries are not only important from an environmental point of view, but also represent an important economic opportunity, provided that the developed processes are selective and efficient. Bioethanol is currently produced from renewable resources in large amounts and, in addition to its use as biofuel, holds considerable promise as a building block for the chemical industry. Indeed, further improvements in production, both in terms of efficiency and feedstock selection, will guarantee availability at competitive prices. The conversion of bioethanol into commodity chemicals, in particular direct ‘drop-in’ replacements is, therefore, becoming increasingly attractive, provided that the appropriate (catalytic) technology is in place. The production of green and renewable 1,3-butadiene is a clear example of this approach. The Lebedev process for the one-step catalytic conversion of ethanol to butadiene has been known since the 1930s and has been applied on an industrial scale to produce synthetic rubber. Later, the availability of low-cost oil made it more convenient to obtain butadiene from petrochemical sources. The desire to produce bulk chemicals in a sustainable way and the availability of low-cost bioethanol in large volumes has, however, resulted in a renaissance of this old butadiene production process. This paper reviews the catalytic aspects associated with the synthesis of butadiene via the Lebedev process, as well as the production of other, mechanistically related bulk chemicals that can be obtained from (bio)ethanol.

Fuel for thought: The dedicated production of 1,3-butadiene from bioethanol is expected to be an effective solution to its current substantial price increase. The Lebedev process for ethanol-to-butadiene conversion is reviewed in detail. The Review also extends to other commodity chemicals that are produced from ethanol and are involved as intermediates or byproducts in the bio-based butadiene production process.

The functionalization of natural fibers is an important task that has recently received considerable attention. We investigated the formation of a hydrophobic layer from amphiphilic diblock copolymer micelles [polystyrene-block-poly(N-methyl-4-vinyl pyridinium iodide)] on natural fibers and on a model surface (mica). A series of micelles were prepared. The micelles were characterized by using cryoscopic TEM and light scattering, and their hydrophobization capability was studied through contact angle measurements, water adsorption, and Raman imaging. Mild heat treatment (130 °C) was used to increase the hydrophobization capability of the micelles. The results showed that the micelles could not hydrophobize a model surface, but could render the natural fibers water repellent both with and without heat treatment. This effect was systematically studied by varying the composition of the constituent blocks. The results showed that the micelle size (and the molecular weight of the constituent diblock copolymers) was the most important parameter, whereas the cationic (hydrophilic) part played only a minor role. We hypothesized that the hydrophobization effect could be attributed to a combination of the micelle size and the shrinkage of the natural fibers upon drying. The shrinking caused the roughness to increase on the fiber surface, which resulted in a rearrangement of the self- assembled layer in the wet state. Consequently, the fibers became hydrophobic through the roughness effects at multiple length scales. Mild heat treatment melted the micelle core and decreased the minimum size necessary for hydrophobization.

Rough and ready: A platform technology for the hydrophobization of natural fibers in water through amphiphilic block copolymer micelle adsorption onto fibers and subsequent heating. The natural roughening of the fibers upon drying facilitates hydrophobization, and heating reveals the hydrophobic core, which allows further hydrophobizing of the surface. Heat treatment tunes the effect of changes to the advancing water contact angles of 120° to 150°.

Emission of SO₂ in flue gas from the combustion of fossil fuels leads to severe environmental problems. Exploration of green and efficient methods to capture SO₂ is an interesting topic, especially at lower SO₂ partial pressures. In this work, ionic liquids (ILs) 1-(2-diethylaminoethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Et₂NEMim][Tf₂N]) and 1-(2-diethylaminoethyl)-3-methylimidazolium tetrazolate ([Et₂NEMim][Tetz]) were synthesized. The performances of the two ILs to capture SO₂ were studied under different conditions. It was demonstrated that the ILs were very efficient for SO₂ absorption. The [Et₂NEMim][Tetz] IL designed in this work could absorb 0.47 g g_IL⁻¹ at 0.0101 MPa SO₂ partial pressure, which is the highest capacity reported to date under the same conditions. The main reason for the large capacity was that both the cation and the anion could capture SO₂ chemically. In addition, the IL could easily be regenerated, and the very high absorption capacity and rapid absorption/desorption rates were not changed over five repeated cycles.

Say it ain′t SO₂! The ionic liquid [Et₂NEMim][Tetz] is synthesized and demonstrated to have an extremely high absorption capacity and rapid absorption/desorption rates for the capture of SO₂. [Et₂NEMim][Tetz] can be regenerated and reused, making it a very attractive ionic liquid for practical SO₂ capture applications.

CuInSe₂ (CISe) absorber layers for thin-film solar cells were fabricated through the selenization of amorphous Cu–In–S nanoparticles, which were prepared by using a low-temperature colloidal process within one minute without any external heating. Two strategies for obtaining highly dense CISe absorber films were used in this work; the first was the modification of nanoparticle surface through chelate complexation with ethanolamine, and the second strategy utilized the lattice expansion that occurred when S atoms in the precursor particles were replaced with Se during selenization. The synergy of these two strategies allowed formation of highly dense CISe thin films, and devices fabricated using the absorber layer demonstrated efficiencies of up to 7.94 % under AM 1.5G illumination without an anti-reflection coating.

CuInS a phase: An amorphous Cu–In–S nanoparticle-based route to form dense CuInSe₂ absorber layers for thin-film solar cells, in which the precursor nanoparticles are prepared within one minute of reaction without external heating, is demonstrated. A power conversion efficiency as high as 7.94 % is achieved by using this method.

Carb your enthousiasm: Carbazole-based sensitizers with high extinction coefficients are synthesized for application in dye-sensitized solar cells (DSCs). The dyes perform efficiently with both iodine and cobalt electrolytes, showing power conversion efficiencies of up to 5.8 % on TiO₂ films of 15 μm thickness, and retaining 90 % of their efficiency in devices with thinner films.

Sloshing hydrogen: Liquid organic hydrogen carriers are high-boiling organic molecules, which can be reversibly hydrogenated and dehydrogenated in catalytic processes and are, therefore, a promising chemical hydrogen storage material. One of the promising candidates is the pair N-ethylcarbazole/perhydro-N-ethylcarbazole (NEC/H₁₂-NEC). The dehydrogenation and possible side reactions on a Pt(111) surface are evaluated in unprecedented detail.

Fertilizers based on phosphate–metal–humate complexes are a new family of compounds that represents a more sustainable and bioavailable phosphorus source. The characterization of this type of complex by using solid ³¹P NMR in several fertilizers, based on single superphosphate (SSP) and triple superphosphate (TSP) matrices, yielded surprising and unexpected trends in the intensity and fine structure of the ³¹P NMR peaks. Computational chemistry methods allowed the characterization of phosphate–calcium–humate complexes in both SSP and TSP matrices, but also predicted the formation of a stable sulfate–calcium–humate complex in the SSP fertilizers, which has not been described previously. The stability of this complex has been confirmed by using ultrafiltration techniques. Preference towards the humic substance for the sulfate–metal phase in SSP allowed the explanation of the opposing trends that were observed in the experimental ³¹P NMR spectra of SSP and TSP samples. Additionally, computational chemistry has provided an assignment of the ³¹P NMR signals to different phosphate ligands as well as valuable information about the relative strength of the phosphate–calcium interactions within the crystals.

Complex fertilizers: The combination of computational chemistry and traditional analysis allows the explanation of unexpected trends in the intensity and fine structure of the peaks obtained through ³¹P NMR spectroscopy for phosphate-based fertilizers. A sulfate–calcium-humate complex is predicted and confirmed, which has not previously been reported.

We report a new class of quaternary polymer electrolyte membranes that comprise poly(ethylene oxide) (PEO), lithium trifluoromethanesulfonylimide (LiTFSI), N-alkyl-N-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr_A,4TFSI) as an ionic liquid, and a SiO₂ filler. The results of differential scanning calorimetry indicate that the addition of SiO₂ and different ionic liquids induces a decrease in the PEO melting enthalpy, which thereby increases the ionic conductivity and the Li transference number. The electrochemical stability is proved by using impedance spectroscopy and cyclic voltammetry. Galvanostatic cycling of Li/LiFePO₄ cells, which comprise the quaternary polymer electrolytes, revealed their superior performance compared to conventional PEO-Li salt electrolytes. In the course of this investigation, a synergistic effect of the combined ionic liquid-ceramic filler modification could be proved at temperatures close to 50 °C.

Electrolyte right! A new and attractive electrolyte based on polyethylene oxide and N-butyl-N-ethyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid as plasticizer shows high conductivity at medium to low temperatures. This allows its employment in a solid polymer lithium battery using LiFePO₄ as the cathode and its efficient operation at temperatures of about 50 °C.

Nonaqueous lithium–oxygen batteries have a much superior theoretical gravimetric energy density compared to conventional lithium-ion batteries, and thus could render long-range electric vehicles a reality. A molecular-level understanding of the reversible formation of lithium peroxide in these batteries, the properties of major/minor discharge products, and the stability of the nonaqueous electrolytes is required to achieve successful lithium–oxygen batteries. We demonstrate that the major discharge product formed in the lithium–oxygen cell, lithium peroxide, exhibits a magnetic moment. These results are based on dc-magnetization measurements and a lithium–oxygen cell containing an ether-based electrolyte. The results are unexpected because bulk lithium peroxide has a significant band gap. Density functional calculations predict that superoxide-type surface oxygen groups with unpaired electrons exist on stoichiometric lithium peroxide crystalline surfaces and on nanoparticle surfaces; these computational results are consistent with the magnetic measurement of the discharged lithium peroxide product as well as EPR measurements on commercial lithium peroxide. The presence of superoxide-type surface oxygen groups with spin can play a role in the reversible formation and decomposition of lithium peroxide as well as the reversible formation and decomposition of electrolyte molecules.

In a spin: The major discharge product formed in the lithium–oxygen cell, lithium peroxide, exhibits a magnetic moment. Density functional calculations predict that “superoxide-like” surface oxygen groups with unpaired electrons exist on nanoparticle surfaces, consistent with magnetic measurements of discharged lithium peroxide products. The “superoxide-like” surface oxygen groups with spin can play a role in the reversible formation and decomposition of lithium peroxide as well as electrolyte molecules.

Catalytic dehydration of D-fructose to 5-hydroxymethylfurfural (HMF) was investigated over a series of Nafion-modified mesocellular silica foam (MCF) materials. By using an impregnation method, Nafion resin was highly dispersed in the ultra-large pores of the MCFs. Highly efficient and selective dehydration of D-fructose to HMF was achieved in dimethyl sulfoxide solvent; an 89.3 % HMF yield with 95.0 % selectivity was obtained in the presence of the Nafion(15)/MCF catalyst. The effects of reaction temperature, reaction time, and solvent on the dehydration of D-fructose were systematically investigated. The catalyst could be regenerated through an ion-exchange method and a high yield was retained after being used five times. As a heterogeneous catalytic process, a possible reaction mechanism for the dehydration of D-fructose over Nafion-modified MCF catalysts was proposed.

Valuable sugars: Nafion-resin-functionalized mesocellular silica foam (MCF) is a strong solid acid that can be prepared through an impregnation method. By using this method, Nafion is well-dispersed in the ultra-large cells of MCFs. This material can easily be reused and exhibits high efficiency and selectivity for the acid-catalyzed dehydration of D-fructose to 5-hydroxymethylfurfural under mild conditions.

A high current density obtained in a limited, nanometer-thick region is important for high efficiency polymer solar cells (PSCs). The conversion of incident photons to charge carriers only occurs in confined active layers; therefore, charge-carrier extraction from the active layer within the device by using solar light has an important impact on the current density and the related to power conversion efficiency. In this study, we observed a surprising result, that is, extracting the charge carrier generated in the active layer of a PSC device, with a thickness-controlled PEDOT:PSS bilayer that acted as a hole extraction layer (HEL), yielded a dramatically improved power conversion efficiency in two different model systems (P3HT:PC₆₀BM and PCDTBT:PC₇₀BM). To understand this phenomenon, we conducted optical strength simulation, photocurrent–voltage measurements, incident photon to charge carrier efficiency measurements, ultraviolet photoelectron spectroscopy, and AFM studies. The results revealed that approximately 60 nm was the optimum PEDOT:PSS bilayer HEL thickness in PSCs for producing the maximum power conversion efficiency.

Two layers are better than one: The systematic increase in power conversion efficiency of polymer solar cells (PSCs) is demonstrated by considering the charge carrier transfer and electric field strength of a device. The unexpected and greatly enhanced power conversion efficiency of PSCs is reported, which can be accomplished by using a PEDOT:PSS hole extraction bilayer. Two different model systems are studied: P3HT:PC₆₀BM and PCDTBT:PC₇₀BM.

In view of their possible use as anode materials in acid direct ethanol fuel cells, the electrocatalytic activity of Pt–Ru and Pt–Ru–M catalysts for ethanol oxidation has been investigated. This minireview examines the effects of the structural characteristics of Pt–Ru, such as the degree of alloying and Ru oxidation state, on the electrocatalytic activity for ethanol oxidation.

Packing a punch: The effect of structural parameters on the ethanol oxidation reaction (EOR) activity of Pt–Ru catalysts is discussed. The EOR activity versus Ru content plots of Pt–Ru catalysts prepared by using different methods go through a maximum, depending on the synthesis method (see image). Alloyed Ru supports ethanol dehydrogenation. Non-alloyed Ru, in the RuO_xH_y form, supports the oxidation of intermediates species in ethanol oxidation.

Highly porous activated carbon with a large surface area and pore volume was synthesized by KOH activation using commercially available activated carbon as a precursor. By modification with polydimethylsiloxane (PDMS), highly porous activated carbon showed superhydrophobicity with a water contact angle of 163.6°. The changes in wettability of PDMS- treated highly porous activated carbon were attributed to the deposition of a low-surface-energy silicon coating onto activated carbon (confirmed by X-ray photoelectron spectroscopy), which had microporous characteristics (confirmed by XRD, SEM, and TEM analyses). Using an easy dip-coating method, superhydrophobic activated carbon-coated sponges were also fabricated; those exhibited excellent absorption selectivity for the removal of a wide range of organics and oils from water, and also recyclability, thus showing great potential as efficient absorbents for the large-scale removal of organic contaminants or oil spills from water.

Supersponge, save the world! Superhydrophobic activated carbon-coated sponges show good selectivity, recyclability, and absorbencies ranging from 2695 to 8586 wt % for a wide range of organic solvents and oils. These materials may have useful applications especially in the fields of oil-spill cleanup and water treatment.

A highly stable high-temperature CO₂ sorbent consisting of scaffold-like Ca-rich oxides (CaAlO) with rapid absorption kinetics and a high capacity is described. The Ca-rich oxides were prepared by annealing CaAlNO₃ layered double hydroxide (LDH) precursors through a sol–gel process with Al(OⁱP)₃ and Ca(NO₃)₂ with Ca²⁺/Al³⁺ ratios of 1:1, 2:1, 4:1, and 7:1. XRD indicated that only LDH powders were formed for Ca²⁺/Al³⁺ ratios of 2:1. However, both LDH and Ca(OH)₂ phases were produced at higher ratios. Both TEM and SEM observations indicated that the CaAlNO₃ LDHs displayed a scaffold-like porous structure morphology rather than platelet-like particles. Upon annealing at 600 °C, a highly stable porous network structure of the CaO-based CaAlO mixed oxide (CAMO), composed of CaO and Ca₁₂Al₁₄O₃₃, was still present. The CAMO exhibited high specific surface areas (up to 191 m² g⁻¹) and a pore size distribution of 3–6 nm, which allowed rapid diffusion of CO₂ into the interior of the material, inducing fast carbonation/calcination and enhancing the sintering-resistant nature over multiple carbonation/calcination cycles for CO₂ absorption at 700 °C. Thermogravimetric analysis results indicated that a CO₂ capture capacity of approximately 49 wt % could be obtained with rapid absorption from the porous 7:1 CAMO sorbents by carbonation at 700 °C for 5 min. Also, 94–98 % of the initial CO₂ capture capability was retained after 50 cycles of multiple carbonation/calcination tests. Therefore, the CAMO framework is a good isolator for preventing the aggregation of CaO particles, and it is suitable for long-term cyclic operation in high-temperature environments.

Caught in a web: A CaAl layered double hydroxide-based scaffold-like network is synthesized in the presence of hexadecyl trimethyl ammonium bromide (CTAB) by using a sol–gel process with Al(OⁱP)₃ and Ca(NO₃)₂ as precursors. The calcined CaAlNO₃ layered double hydroxides display rapid CO₂ absorption kinetics in addition to a long-term cyclic operation in a high-temperature environment.

Graphene is considered as a rising-star material because of its unique properties and it is a promising material for applications in many fields. In recent years, experiments on graphene fabricated by using versatile methods have shed light on the crucial problem of aggregation and restacking, which is induced by strong π–π stacking and van der Waals forces, but preparation methods for real-world applications are still a great challenge. Here we report a facile, rapid, and environmentally friendly process, the burn–quench method, that allows large-scale and controlled synthesis of ordered mesoporous nanographene with 1–5 layers, which has a high surface area and electric conductivity. Electrodes composed of nanographene with a mesoporous architecture used both in electrochemical capacitors and lithium-ion batteries have a high specific capacitance, rate capability, energy density, and cyclic stability. Our results represent an important step toward large-scale graphene synthesis based on this new burn–quench method for applications in high-performance electrochemical energy storage devices.

Nanographene electrodes are go: The large-scale production of nanographene with a controlled mesoporous architecture is achieved by a new burn–quench method, which involves the ignition of Mg ribbons in CO₂ followed by in situ quenching. Nanographene with a mesoporous architecture has a high surface area and high conductivity.

Hausmannite Mn₃O₄ octahedral nanoparticles of 18.3±7.0 nm with (101) facets have been prepared by an oxygen-mediated growth. The electrochemical properties of the Mn₃O₄ particles as pseudocapacitive cathode materials were characterized both in half-cells and in button-cells. The Mn₃O₄ nanoparticles exhibited a high mass-specific capacitance of 261 F g⁻¹, which was calculated from cyclic voltammetry analyses, and a capacitive retention of 78 % after 10 000 galvanostatic charge–discharge cycles. The charge-transfer mechanisms of the Mn₃O₄ nanoparticles were further studied by using synchrotron-based in situ X-ray absorption near edge spectroscopy and XRD. Both measurements showed concurrently that throughout the potential window of 0–1.2 V (vs. Ag/AgCl), a stable spinel structure of Mn₃O₄ remained, and a reversible electrochemical conversion between tetrahedral [Mn^IIO₄] and octahedral [Mn^IIIO₆] units accounted for the redox activity. Density functional theory calculations further corroborated this mechanism by confirming the enhanced redox stability afforded by the abundant and exposed (101) facets of Mn₃O₄ octahedra.

Two-faced: Hausmannite Mn₃O₄ nanoparticles with (101) facets were prepared through oxygen-mediated growth. The Mn₃O₄ octahedral nanoparticles exhibited high mass-specific capacitance and cycle ability for supercapacitor reactions. The charge-storage mechanisms of the nanoparticles during electrochemical redox reactions were further studied by using in situ synchrotron-based methods.

Intensive research on oxygen reduction reaction (ORR) catalysts has been undertaken to find a Pt substitute or reduce the amount of Pt. Ag nanoparticles are potential Pt substitutes; however, the weak oxygen adsorption energy of Ag prompted investigation of other catalysts. Herein, we prepared AgCu bimetallic nanoparticle (NP) systems to improve the catalytic performance and compared the catalytic performance of Ag, Cu, AgCu (core–shell), and AgCu (alloy) NP systems as new catalyst by investigating the adsorption energy of oxygen and the activation energy of oxygen dissociation, which is known to be the rate-determining step of ORR. By analyzing HOMO-level isosurfaces of metal NPs and oxygen, we found that the adsorption sites and the oxygen adsorption energies varied with different configurations of NPs. We then plotted the oxygen adsorption energies against the energy barrier of oxygen dissociation to determine the catalytic performance. AgCu (alloy) and Cu NPs exhibited strong adsorption energies and low activation-energy barriers. However, the overly strong oxygen adsorption energy of Cu NPs hindered the ORR.

AgCu (alloy) nanoparticle: The adsorption energy of oxygen and the activation energy of oxygen dissociation are important factors that determine the performance of oxygen reduction reaction catalysts. We propose the utilization of a AgCu-alloy nanoparticle system as a potential highly efficient catalyst in this setting because it possesses good catalytic properties and prevents Cu oxidation.

Azole anions are key components in CO₂ capture materials that include ionic liquids and porous solids. Herein, we use density functional theory (DFT) and a Langmuir-type adsorption model to study azole anion–CO₂ interactions. Linear CO₂ has to be bent by approximately 45° to form an NC bond within the azole ring. The energy cost of bending renders CO₂ absorption much more difficult compared to SO₂ absorption. For different azole anions, the number of nitrogen atoms in the ring and the natural bond orbital energy of the reacting nitrogen lone pair, both linearly correlate with the calculated reaction enthalpy and are useful handles for new sorbent designs. Unlike for SO₂, the azole parent architecture (unsubstituted) does not allow successive CO₂ absorption under mild conditions (<0.12 MPa and at room temperature). Experimental CO₂ and SO₂ absorption isotherms are reproduced by using the Langmuir model parameterized with the calibrated DFT reaction enthalpies. This study provides insight for designing azole-based CO₂-capture materials.

Catch me if you can: Azole anions represent a key component in CO₂ absorption materials. A variety of different azole anions have been investigated for their reactivity with CO₂ by using DFT calculations and a Langmuir adsorption model. Unlike SO₂, multi-site CO₂ absorption does not occur for azole anions under normal conditions. This study provides insight into designing azole-based CO₂-capture materials.

The oxygen reduction reaction (ORR) is undoubtedly the most important fuel-cell cathodic reaction. In this work, a detailed electrochemical analysis of the ORR on Pt (111) in nonadsorbing electrolytes was performed, which included the high-potential region E_up=1.15 V while ensuring the electrode surface structure stability. Our results suggest that the reduction of a soluble intermediate species formed during the ORR is the rate-determining step in the whole reaction mechanism. This species does not undergo any other electrochemical reaction at E>0.9 V and may accumulate close to the electrode surface. Together with dissolved O₂, this intermediate may modify the oxide-growth dynamics on Pt (111). Hence, both species interact with the electrode surface through complex catalytic networks. Under certain experimental conditions, oxygenated species from the oxidation of Pt (111) may enhance the overall ORR current. These results propose an alternative to explain the current state of the art for this fundamental process.

A radical idea! The oxygen reduction reaction on Pt (111) in the high potential region is not inhibited by the initial oxidized surface states. Instead, the reduction of a soluble intermediate species apparently is the rate determining step.

Committed carbenes: The convenient application of bidentate carbene ligands is described for the hydrogenation of carboxylic acid esters. The ligand precursors are easily synthesized through the dimerization of N-substituted imidazoles with diiodomethane. The catalyst is generated in situ and exhibits good activity and functional group tolerance for the hydrogenation of aromatic and aliphatic carboxylic acid esters.

Cellulose and cellobiose were selectively converted into sorbitol over water-tolerant phosphotungstic acid (PTA)/metal– organic-framework-hybrid-supported ruthenium catalysts, Ru-PTA/MIL-100(Cr), under aqueous hydrogenation conditions. The goal was to investigate the relationship between the acid/metal balance of bifunctional catalysts Ru-PTA/MIL-100(Cr) and their performance in the catalytic conversion of cellulose and cellobiose into sugar alcohols. The control of the amount and strength of acid sites in the supported PTA/MIL-100(Cr) was achieved through the effective control of encapsulated-PTA loading in MIL-100(Cr). This design and preparation method led to an appropriately balanced Ru-PTA/MIL-100(Cr) in terms of Ru dispersion and hydrogenation capacity on the one hand, and acid site density of PTA/MIL-100(Cr) (responsible for acid-catalyzed hydrolysis) on the other hand. The ratio of acid site density to the number of Ru surface atoms (n_A/n_Ru) of Ru-PTA/MIL-100(Cr) was used to monitor the balance between hydrogenation and hydrolysis functions; the optimum balance between the two catalytic functions, that is, 8.84<n_A/n_Ru<12.90, achieves maximum conversion of cellulose and cellobiose into hexitols. Under the applied reaction conditions, optimal results (63.2 % yield in hexitols with a selectivity for sorbitol of 57.9 % at complete conversion of cellulose, and 97.1 % yield in hexitols with a selectivity for sorbitol of 95.1 % at complete conversion of cellobiose) were obtained using a Ru-PTA/MIL-100(Cr) catalyst with loadings of 3.2 wt % for Ru and 16.7 wt % for PTA. This research thus opens new perspectives for the rational design of acid/metal bifunctional catalysts for biomass conversion.

Acid/Metal Balance: Bifunctional catalysts containing ruthenium and polyoxometalates as active species with a metal-organic framework as support and encapsulation matrix, respectively, are synthesized. Excellent yields in sorbitol are obtained in the conversion of cellobiose and ball-milled cellulose. The evaluation of the balance between the hydrogenation and hydrolysis functions of these bifucntional catalysts reveals that by carefully balancing the ratio of acid site density and the number of metal surface atoms a maximum conversion can be achieved.

A series of Pt catalysts supported on Al₂O₃ that was doped with different amounts of CeO₂ was developed, characterized, and tested in the aqueous-phase reforming (APR) of glycerol to H₂. Catalyst 3Pt/3CeAl, which bore 3 wt % Pt on a support that contained 3 wt % CeO₂, showed the highest carbon conversion to gas (85 %) and the highest H₂ yield (80 %) for a feedstock of 1 wt % glycerol in water at 240 °C and 40 bar. A CeO₂/Al₂O₃ support with only 1 wt % Pt also showed high H₂ selectivity and carbon conversion to gas, as well as a much lower CH₄ yield than the benchmark 3Pt/Al catalyst, clearly demonstrating that doping the support with 3 wt % CeO₂ improved the APR of glycerol. H₂ chemisorption results showed that the highest metal dispersion (58 %) and active surface area (4.3 m² g⁻¹) were achieved for the support that contained 3 wt % CeO₂, and this effect appeared to be primarily responsible for the high H₂ yield and carbon conversion to gas. No CO was observed in the product gas; therefore, this gas could potentially be used directly in proton exchange membrane fuel cells. Thus, including CeO₂ in the Al₂O₃ catalyst support enhanced both the activity and selectivity towards H₂ of a Pt catalyst for the APR of glycerol.

Pt darn good: Pt catalysts supported on CeO₂-doped Al₂O₃ exhibit higher activity and selectivity towards H₂ production in the aqueous-phase reforming of glycerol. Optimization of the CeO₂/Al₂O₃ ratio, higher metal dispersion, and increased active surface area are primarily responsible for the higher glycerol conversion rate and H₂ yield.

A solid acid foam-structured catalyst based on a binderless zirconium phosphate (ZrPO) coating on aluminum foam was prepared. The catalyst layer was obtained by performing a multiple washcoating procedure of ZrPO slurry on the anodized aluminum foam. The effect of the pretreatment of ZrPO, the concentration of the slurry, and the amount of coating on the properties of the foam was studied. The catalytic properties of the prepared foams have been evaluated in the dehydration of glucose to 5-hydroxymethylfurfural (HMF) in a biphasic reactor. The catalytic behavior of ZrPO foam-based catalysts was studied in a rotating foam reactor and compared with that of bulk ZrPO. The effect of a silylation procedure on the selectivity of the process was shown over bulk and foam catalysts. This treatment resulted in a higher selectivity due to the deactivation of unselective Lewis acid sites. Addition of methylisobutylketone leads to extraction of HMF from the aqueous phase and stabilization of the selectivity to HMF over bulk ZrPO. A more intensive contact of the foam with the aqueous and organic phases leads to an increase in the selectivity and resistance to deactivation of the foam in comparison with a bulk catalyst.

Cat-Al-ytically coated: The preparation of a solid acid foam based on zirconium phosphate (ZrPO) coating on aluminum foam is described. The catalytic properties are evaluated in the dehydration of glucose to 5-hydroxymethylfurfural in a biphasic rotating foam reactor (see picture). The silylation procedure leads to a higher selectivity, and a more intensive contact of the foam with aqueous and organic phases leads to an increase of selectivity and stability.

The functionalization of micro- and nano-sized metal-oxide powders offers many advantages because of their large surface areas and, therefore, the large number of functional molecules that can be grafted onto the grain surfaces. Porphyrin molecules on large band-gap semiconducting metal oxides represent key materials for many different optical and electronic applications. Herein, we have proposed a general two-step procedure for the functionalization of metal-oxide crystals with dye-sensitizers. In particular, we functionalized SnO₂ nanoparticles with a monolayer of the bifunctional trichloro[4-(chloromethyl)phenyl]silane. Then, a monolayer of 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyne was covalently bound to the silanized SnO₂ grains. IR, UV/Vis, and luminescence measurements were used for optical characterization. The measured footprint of the grafted porphyrin molecules indicated total surface coverage of the grains. The surface electronic characterization was performed by using X-ray photoelectron spectroscopy. Emission measurements revealed two strong bands at 664.1 and 721.0 nm that were attributed to the porphyrin monolayer assembled on the surface of the SnO₂ crystals.

All wrapped up: SnO₂ crystals are functionalized with a porphyrin monolayer and the resulting functionalized material is fully characterized. The obtained system shows luminescent properties and has the potential to find application in optical and electronic devices. The two-step procedure for the functionalization of metal-oxide crystals with dye-sensitizers could be applied to a range of metal-oxide semiconductors.

Sweets for my sweet: The production and isolation of 5-hydroxymethylfurfural (HMF) in high yield and purity is demonstrated by using a combination of glucose–fructose isomerization with sweetzyme in wet tetraethylammonium bromide (TEAB) and clean fructose dehydration to HMF catalyzed by using HNO₃ under moderate conditions, which allow the reuse of any unreacted glucose and TEAB.

Safe only in a microreactor! The synthesis of adipic acid from cyclohexene by tungstic acid-catalyzed oxidation using hydrogen peroxide following the classical Noyori protocol can be accomplished in good yields with residence times as short as 20 min at 140 °C using a safe and scalable microreactor environment. Under these intensified conditions the use of a phase-transfer catalyst is not required.

Aqueous-phase reforming (APR) of biocarbohydrates is conducted in a catalytically stable washcoated microreactor where multiphase hydrogen removal enhances hydrogen efficiency. Single microchannel experiments are conducted following a simplified model based on the microreactor concept. A coating method to deposit a Pt-based catalyst on the microchannel walls is selected and optimized. APR reactivity tests are performed by using ethylene glycol as the model compound. Optimum results are achieved with a static washcoating technique; a highly uniform and well adhered 5 μm layer is deposited on the walls of a 320 μm internal diameter (ID) microchannel in one single step. During APR of ethylene glycol, the catalyst layer exhibits high stability over 10 days after limited initial deactivation. The microchannel presents higher conversion and selectivity to hydrogen than a fixed-bed reactor. The benefits of using a microreactor for APR can be further enhanced by utilizing increased Pt loadings, higher reaction temperatures, and larger carbohydrates (e.g., glucose). The use of microtechnology for aqueous-phase reforming will allow for a great reduction in the reformer size, thus rendering it promising for distributed hydrogen production.

Left out to dry: Aqueous-phase reforming (APR) of biocarbohydrates is conducted for the first time in a catalytically stable washcoated microchannel in which multiphase hydrogen removal enhances the hydrogen efficiency. The microchannel presents higher conversion of ethylene glycol and higher selectivity to hydrogen than a fixed-bed reactor. The use of microreactor technology for APR allows for a great reduction in the reformer size, which is promising for distributed hydrogen production.

Some like it hot: Lactic acid is an important commodity chemical that is mainly used in the food industry or for the manufacture of biodegradable plastics. A highly efficient strategy for the conversion of carbohydrates from biomass to lactic acid through alkaline hydrolysis in superheated water is presented.

Changing the sheets: Hollow TiO₂ porous nanosheets (HTPNs) are prepared on ITO glass through an improved TiO₂ polycrystalline shell-assisted cation exchange by using ZnO porous nanosheets (grown by using indirect electrodeposition) as a template. Quantum dot-sensitized solar cells based on HTPNs exhibit a high performance, and other photoelectrochemical devices are expected to be prepared based on HTPNs.

The cover picture shows an illustration of a graphene sheet decorated with different types of oxygen functionalities and the oxidative dehydrogenation reaction of isobutane to isobutene that is catalyzed by the functionalized edge sites. The micrograph background image is of the same graphenes recorded by Schwartz et al using a new helium-ion microscope at the Center for Nanophase Materials Sciences/Oak Ridge National Laboratory (CNMS/ORNL). The application of oxygen-modified graphene for gas-phase reactions, which is reported on page 840, is a new approach to study the scarcely explored field of carbon catalysis. This field of metal-free carbon-based catalysis is of importance for developing a more sustainable and environmentally friendly catalytic oxidative dehydrogenation process as carbon materials can be easily disposed of after their lifetime.

Invited for this month′s cover is the group from the Center for Nanophase Materials Sciences (CNMS) at the Oak Ridge National Laboratory. The illustration is of the catalytic activity of the reported oxygen-functionalized few-layer graphenes, whereas the micrograph background image is of the same graphenes recorded by the authors using a new helium-ion microscope at the CNMS. Read the full text of the article at 10.1002/cssc.201200756

Invited for this months cover is the group from the Center for Nanophase Materials Sciences (CNMS) at the Oak Ridge National Laboratory. The illustration is of the catalytic activity of the reported oxygen-functionalized few-layer graphenes, whereas the micrograph background image is of the same graphenes recorded by the authors using a new helium-ion microscope at the CNMS. Read the full text of the article at 10.1002/cssc.201200756

Novel Process Windows make use of process conditions that are far from conventional practices. This involves the use of high temperatures, high pressures, high concentrations (solvent-free), new chemical transformations, explosive conditions, and process simplification and integration to boost synthetic chemistry on both the laboratory and production scale. Such harsh reaction conditions can be safely reached in microstructured reactors due to their excellent transport intensification properties. This Review discusses the different routes towards Novel Process Windows and provides several examples for each route grouped into different classes of chemical and process-design intensification.

Windows provide panoramas: Novel Process Windows are a chance to explore new horizons for the processing industry. They make use of process conditions that are far from conventional practices. This Review discusses different routes and provides several examples for each route based on chemical and process-design intensification classification (see picture).

Who needs the nobles? Ideally, devices to harvest solar energy into fuels would, in addition to having very high turnover numbers, make use of earth-abundant materials. In this Highlight we focus on a recent example in which a copper-based photosensitizer is used, in combination with an iron-based catalyst for light-driven proton reduction.

Made to order: Rechargeable batteries are fabricated by using organic electron acceptors and donors as active cathode materials. Their output voltage and cycle performance can be tuned by organic chemistry techniques. The output voltages are linked to both the redox potentials and the energy levels of the frontier molecular orbitals of the cathode materials, enabling to predict the output voltage at an early stage of the design.

Which cleavage do you prefer? With a combination of density functional theory (DFT) calculations, surface science studies, and reactor evaluations, Mo₂C is identified as a highly selective HDO catalyst to selectively convert biomass-derived oxygenates to unsaturated hydrocarbons through selective CO bond scissions without CC bond cleavage. This provides high-value HDO products for utilization as feedstocks for chemicals and fuels; this also reduces the overall consumption of H₂.

Storable sunshine, reusable rays: A solar rechargeable redox flow battery is proposed based on the photoregeneration of I₃⁻/I⁻ and [Fe(C₁₀H₁₅)₂]⁺/Fe(C₁₀H₁₅)₂ soluble redox couples, which can be regenerated by flowing from a discharged redox flow battery (RFB) into a dye-sensitized solar cell (DSSC) and then stored in tanks for subsequent RFB applications This technology enables effective solar-to-chemical energy conversion.

Catalytic carbon: Nitrogen-doped porous carbon (CN_x) electrocatalysts are derived from inexpensive melamine formaldehyde resins. These potential PEMFC catalysts are synthesized by using a facile method, which yields materials that contain a meso- and macroporous structure. The carbon-based materials display attractive catalytic activity toward ORR and superior stability compared to a commercial Pt-based catalyst.

Solid wood, metal finnish: Instead of burning waste wood treated with chromated copper arsenite (CCA) or disposing of it in landfills, the CCA-treated wood can be used as a raw material for the production of chemicals. Catalytic or alkaline oxidation together with very mild sulfuric acid extraction produces an easily enzymatically hydrolyzable material. Usage as a raw material for the chemical industry in this manner demonstrates a sustainable and value-added waste management process.

Less is More: Atomically dispersed gold species catalyze the decomposition of formic acid through the dehydrogenation pathway at near-ambient temperatures. Gold on ceria is demonstrated to be an effective and stable catalyst. By using this catalyst, mechanistic insights are obtained that can lead to the use of trace amounts of gold to achieve robust and cost-effective catalysts.

A simple and efficient microwave-assisted HNb₃O₈ catalytic process is proposed for the dehydration of carbohydrates in the aqueous phase. A 5-hydroxymethylfurfural (HMF) yield of 55.9 % was achieved at a high substrate/catalyst weight ratio of 50 from a 10 wt % fructose solution, which is close to the yield achieved by homogeneous aqueous systems. The critical factor for this performance is the fast in situ exfoliation of layered HNb₃O₈ with the aid of microwave irradiation, which leads to quasi-homogeneous catalytic behavior. Importantly, the catalytic system is also applicable for the one-pot production of HMF from di- and polysaccharides, such as inulin, through a consecutive hydrolysis–dehydration reaction. Additionally, the unique restacking feature of the exfoliated HNb₃O₈ ensures the good reusability of the catalyst.

Between the sheets: A simple and efficient microwave-assisted HNb₃O₈ catalytic process is proposed for the dehydration of carbohydrates in a sustainable pure aqueous system, in which the fast in situ exfoliation of the layered HNb₃O₈ under microwave irradiation is crucial for the remarkable catalytic performance.

Furfural and 5-hydroxymethylfurfural (HMF) are important biomass-derived platform chemicals that can be obtained from the dehydration of lignocellulosic sugars. A possible route for the derivatization of furanics is their oxidation to afford a broad range of chemicals with promising applications (e.g., diacids, hydroxyl acids, aldehyde acids, monomers for novel polymers). Herein we explore the organic peracid-assisted oxidation of furanics under mild reaction conditions. Using lipases as biocatalysts, alkyl esters as acyl donors, and aqueous solutions of hydrogen peroxide (30 % v/v) added stepwise, peracids are formed in situ, which subsequently oxidize the aldehyde groups to afford carboxylic acids with high yields and excellent selectivities. Furthermore, the use of an immobilized silica-based 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) affords the selective oxidation of the hydroxymethyl group of HMF to afford 2,5-diformylfuran. That product can be subsequently oxidized using again lipases for the in situ peracid formation to yield 2,5-furandicarboxylic acid, which is considered to be a key building block for biorefineries. These lipase-mediated reactions proceeded efficiently even with high substrate loadings under still non-optimized conditions. Overall, a proof-of-concept for the oxidation of furanics (based on in situ formed organic peracids as oxidants) is provided.

Value added per-acid: The use of lipases as biocatalysts for the in situ production of organic peracids has been explored. A new peracid-based methodology for the oxidative valorization of biomass-derived furanics is subsequently formulated. This may bring innovative approaches in the field once optimization and process-development considerations are taken into account.

Desilication of commercial MFI-type (ZSM-5) zeolites in solutions of alkali metal hydroxides is demonstrated to generate highly selective heterogeneous catalysts for the aqueous-phase isomerization of biobased dihydroxyacetone (DHA) to lactic acid (LA). The best hierarchical ZSM-5 sample attains a LA selectivity exceeding 90 %, which is comparable to that of the state-of-the-art catalyst (i.e., the Sn-beta zeolite); this optimized hierarchical catalyst is recyclable over three runs. The Lewis acid sites, which are created through desilication along with the introduction of mesoporosity, are shown to play a crucial role in the formation of the desired product; these cannot be achieved by using other post-synthetic methods, such as steaming or impregnation of aluminum species. Desilication of other metallosilicates, such as Ga–MFI, also leads to high LA selectivity. In the presence of a soluble aluminum source, such as aluminum nitrate, alkaline-assisted alumination can introduce these unique Lewis acid centers in all-silica MFI zeolites. These findings highlight the potential of zeolites in the field of biomass-to-chemical conversion, and expand the applicability of desilication for the generation of selective catalytic centers.

Making the right site: Lewis acid centers generated upon the desilication of commercial MFI zeolites in alkaline media are shown to catalyze the isomerization of dihydroxyacetone to lactic acid, competing with tin-containing zeolites. This opens exciting perspectives for the use of hierarchical zeolites with tailored porous and acidic properties in biomass-to-chemical conversions.

Nanostructured graphitic forms of carbons have shown intersting potential for catalysis research and are ideal candidates to substitute the conventional metal-oxide catalysts because they can be easily disposed, which enables a greener, more sustainable catalytic process. Few-layer graphene and its functionalized form offer the opportunity to investigate the nature of graphitic active sites for oxidation reactions in well-defined carbon-based catalysts. In this paper, we report the utilization of oxygen-functionalized few-layer graphene sheets containing variable amounts of oxygen in the heterogeneous catalytic oxidative dehydrogenation (ODH) reaction of isobutane at 400ºC. Interestingly, there is poor correlation between oxygen content and catalytic performance. Carbonyl groups were found to be highly stable, and graphene that had higher sp² character, the lowest oxygen content, and fewer edge sites presented the lowest specific rate of isobutane reaction, although the isobutene selectivity remained high. The reoxidation of the graphene surface occurred at the same rate as the ODH reaction suggesting a Mars–van Krevelen type of mechanism, similar to that which takes place on oxide surfaces. These results appear to suggest that a higher fraction of exposed edges where oxygen active sites can be formed and exchanged should lead to more active catalysts for ODH reactions.

Edge exposure: Few-layer graphene and its oxygen-functionalized form are used to investigate the nature of graphitic active sites for the heterogeneous catalytic oxidative dehydrogenation reaction. No clear correlation is observed between isobutane consumption rate and the oxygen content of the samples; therefore, demonstrating that not all of the oxygen functionalities are active for this reaction.

Eliminating the expensive and failure-prone proton exchange membrane (PEM) together with the platinum-based anode and cathode catalysts would significantly reduce the high capital and operating costs of low-temperature (<373 K) fuel cells. We recently introduced the Swiss-roll mixed-reactant fuel cell (SR-MRFC) concept for borohydride–oxygen alkaline fuel cells. We now present advances in anode electrocatalysis for borohydride electrooxidation through the development of osmium nanoparticulate catalysts supported on porous monolithic carbon fiber materials (referred to as an osmium 3D anode). The borohydride–oxygen SR-MRFC operates at 323 K and near atmospheric pressure, generating a peak power density of 1880 W m⁻² in a single-cell configuration by using an osmium-based anode (with an osmium loading of 0.32 mg cm⁻²) and a manganese dioxide gas-diffusion cathode. To the best of our knowledge, 1880 W m⁻² is the highest power density ever reported for a mixed-reactant fuel cell operating under similar conditions. Furthermore, the performance matches the highest reported power densities for conventional dual chamber PEM direct borohydride fuel cells.

Roll with it: A mixed-reactant alkaline borohydride–oxygen fuel cell with a Swiss-roll design is presented, which uses an osmium anode and a manganese dioxide gas-diffusion cathode. For a single-cell mixed-reactant fuel cell, a superficial peak power density of 1880 W m⁻² is achieved, which is higher than any low temperature mixed-reactant fuel cell so far reported in the literature with an anode electrocatalyst loading of less than 0.5 mg cm⁻².

A highly reflective counter electrode is prepared through the deposition of alternating layers of organized mesoporous TiO₂ (om-TiO₂) and colloidal SiO₂ (col-SiO₂) nanoparticles. We present the effects of introducing this counter electrode into dye-sensitized solar cells (DSSCs) for maximizing light harvesting properties. The om-TiO₂ layers with a high refractive index are prepared by using an atomic transfer radical polymerization and a sol–gel process, in which a polyvinyl chloride-g-poly(oxyethylene) methacrylate graft copolymer is used as a structure-directing agent. The col-SiO₂ layers with a low refractive index are prepared by spin-coating commercially available silica nanoparticles. The properties of the Bragg stack (BS)-functionalized counter electrode in DSSCs are analyzed by using a variety of techniques, including spectroscopic ellipsometry, SEM, UV/Vis spectroscopy, incident photon-to-electron conversion efficiency, electrochemical impedance spectroscopy, and intensity modulated photocurrent/voltage spectroscopy measurements, to understand the critical factors contributing to the cell performance. When incorporated into DSSCs that are used in conjunction with a polymerized ionic liquid as the solid electrolyte, the energy conversion efficiency of this solid-state DSSC (ssDSSC) approaches 6.6 %, which is one of the highest of the reported N719 dye-based ssDSSCs. Detailed optical and electrochemical analyses of the device performance show that this assembly yields enhanced light harvesting without the negative effects of charge recombination or electrolyte penetration, which thus, presents new possibilities for effective light management.

What′s in your reflection? A highly reflective counter electrode based on a Bragg stack is prepared by the deposition of alternating layers of organized mesoporous TiO₂ and colloidal SiO₂ nanoparticles. By using this in conjunction with a polymerized ionic liquid, the energy conversion efficiency of the solid-state dye-sensitized solar cell (ssDSSC) is among the highest of ssDSSCs based on the N719 dye.

The catalytic performance of a set of metal–organic frameworks [CuBTC, FeBTC, MIL-100(Fe), MIL-100(Cr), ZIF-8, MIL-53(Al)] was investigated in the Prins condensation of β-pinene with formaldehyde and compared with the catalytic behavior of conventional aluminosilicate zeolites BEA and FAU and titanosilicate zeolite MFI (TS-1). The activity of the investigated metal–organic frameworks (MOFs) increased with the increasing concentration of accessible Lewis acid sites in the order ZIF-8<MIL-53(Al)<FeBTC<MIL-100(Cr)<MIL-100(Fe). Unwanted β-pinene-like isomerization takes place on the strong Brønsted acid sites of zeolites BEA and FAU, which showed significantly lower selectivity to the target nopol than the MOFs. Its high activity, the preservation of its structure and active sites, and the possibility to use it in at least three catalytic cycles without loss of activity make MIL-100 (Fe) the best performing catalyst of the series for the Prins condensation of β-pinene and paraformaldehyde. Our report exemplifies the advantages of MOFs over zeolites as solid catalysts in liquid-phase reactions for the production of fine chemicals.

Green and efficient: Its high activity in the Prins condensation of β-pinene and paraformaldehyde, the preservation of its structure and active sites, and the possibility to use MIL-100 (Fe) in at least three catalytic cycles without loss of its activity are established. Our report exemplifies the advantages of MOFs over zeolites as solid catalysts in liquid-phase reactions for the production of fine chemicals.

Lecitase Ultra was immobilized on Amberlites XAD2 and XAD4, through physical entrapping under conventional stirring or ultrasound irradiation, and characterized by standard techniques. The resulting immobilized biocatalysts were utilized in the valorization of an acidic food-derived residue from a palm oil refining process to produce monoacylglycerols from isopropylidene glycerol under batch and continuous flow conditions. Results indicated that the immobilized biocatalysts could moderately convert the food waste residue (max. conversion 50–60 %), exhibiting interesting stability under continuous flow conditions.

Trapped into action: Lecitase Ultra is immobilized on Amberlites XAD2 and XAD4 through physical entrapping under conventional stirring or ultrasound irradiation (see picture). The resulting immobilized biocatalysts are utilized in the valorization of an acidic food-derived residue from a palm oil refining process to produce monoacylglycerols from isopropylidene glycerol under batch and continuous flow conditions.

Porous graphitic carbon nanosheets (PGCS) are synthesized by an in situ self-generating template strategy based on the carburized effect of iron with cornstalks. Cornstalks firstly coordinate with [Fe(CN)₆]⁴⁻ ions to form the cornstalk–[Fe(CN)₆]⁴⁻ precursor. After carbonization and removal of the catalyst, PGCS are obtained. Series experiments indicate that PGCS can only be formed when using an iron-based catalyst that can generate a carburized phase during the pyrolytic process. The unique structures of PGCS exhibit excellent capacitive performance. The PGCS-1-1100 sample (synthesized from 0.1 M [Fe(CN)₆]⁴⁻ with a carbonization temperature of 1100 °C), which shows excellent electrochemical capacitance (up to 213 F g⁻¹ at 1 A g⁻¹), cycling stability, and rate performance in 6 M KOH electrolyte. In the two-electrode symmetric supercapacitors, the maximum energy densities that can be achieved are as high as 9.4 and 61.3 Wh kg⁻¹ in aqueous and organic electrolytes, respectively. Moreover, high energy densities of 8.3 and 40.6 Wh kg⁻¹ are achieved at the high power density of 10.5 kW kg⁻¹ in aqueous and organic electrolytes, respectively. This strategy holds great promise for preparing PGCS from natural resources, including cornstalks, as advanced electrodes in supercapacitors.

Fields of gold? Porous graphitic carbon nanosheets (PGCS) have been synthesized by a self-generating template strategy based on the carburized effect of iron with cornstalks. The synthesized PGCS exhibit excellent capacitive performance owing to their unique porous nanostructures and graphitic carbon nanosheets, which can facilitate ion and electron transport, respectively.

Tetramethylammonium-based molten salts bearing a β-amino acid anion (TMAAs) are synthesized through Michael addition reactions of amines with methyl acrylate followed by hydrolysis and subsequent neutralization by using aqueous tetramethylammonium hydroxide. The CO₂ capture performances of the TMAAs are evaluated and are shown to interact with CO₂ in a 1:1 mode in both water and alcohol. FTIR and ¹³C NMR spectroscopic studies on the interactions of TMAAs with CO₂ indicate that the type of CO₂ adduct varies with the solvent used. When water is used as the solvent, a bicarbonate species is produced, whereas hydroxyethylcarbonate and methylcarbonate species are generated in ethylene glycol and methanol, respectively. Computational calculations show that the carboxylate groups of TMAAs contribute towards the formation and stabilization of 1:1 CO₂ adducts through hydrogen bonding interactions with the hydrogen atoms of the amino groups.

Catch me if you can: Tetramethylammonium salts bearing a β-amino acid anion (TMAAs) are synthesized through Michael addition reactions of amines with methyl acrylate, subsequent hydrolysis, and neutralization with aqueous tetramethylammonium hydroxide. These TMAAs interact with CO₂ in a 1:1 mode in ethylene glycol, which forms hydroxyethylcarbonate species. The driving force for the 1:1 bonding appears to be the intramolecular hydrogen bonding network exerted through the carboxylate group.

The electrochemical performance of reduced graphite oxide (RGO) anchored with nano Sn particles, which are synthesized by a reduction method, is presented. The Sn nanoparticles are uniformly distributed on the surface of the RGO matrix and the size of the particles is approximately 5–10 nm. The uniform distribution effectively accommodates the volume expansion experienced by Sn particles during cycling. The observed electrochemical performance (97 % capacity retention) can be ascribed to the flexible RGO matrix with uniform distribution of Sn particles, which reduces the lithium-ion diffusion path lengths; therefore, the RGO matrix provides more stability to the Sn particles during cycling. Such studies on Sn nanoparticles anchored on RGO matrices have not been reported to date.

RGO/Nano Sn: This study investigates the electrochemical performance of reduced graphite oxide (RGO) anchored with nano Sn. This material demonstrates superior electrochemical performance that is associated with the flexible RGO matrix and the uniform distribution of Sn particles, which reduce the lithium-ion diffusion path length; therefore, the RGO matrix provides more stability to tin particles during cycling.

Calcium oxide is proposed as an innocuous acid scavenger for the chemoselective synthesis of amide- and ester-type compounds. Although these molecules have wide spread applications in organic and pharmaceutical chemistry, and a large number of routes have been designed for their synthesis, the development of more efficient and environmentally friendly acylation strategies remains an ongoing challenge. The use of CaO allows for the stoichiometric acylation of primary alcohols in the presence of phenols or tertiary alcohols; amines can also be subjected to acylation reactions in the presence of hydroxyl groups. Chirality is obtained through acylation if the starting material is an optically pure alcohol or if a chiral acylating agent is used. Furthermore, the use of 2-methyltetrahydrofuran (2-MeTHF), a more ecofriendly solvent, leads to maximized yields. This protocol is successfully applied to the synthesis of an interesting N-aryloxazolidin-2-one intermediate for the preparation of linezolid-type compounds.

Scrounger! A sustainable chemoselective protocol is presented for the stoichiometric acylation of alcohols and amines. This methodology utilises CaO as an effective acid scavenger. Acylation of primary alcohols is achieved chemoselectively over phenols or tertiary alcohols. Improved yields are obtained by using biocompatible 2-methyltetrahydrofuan instead of diethyl ether.

The synthesis of DNL-6 with a high concentration of Si (4 Al) environments [Si/(Si+Al+P)=0.182 mol, denoted as M-DNL-6] is demonstrated. This represents the highest reported concentration of such environments in silicoaluminophosphate (SAPO) molecular sieves. Adsorption studies show that the high Si (4 Al) content in M-DNL-6, with an increased number of Brønsted acid sites in the framework, greatly promotes the adsorption of CO₂. M-DNL-6 exhibits a large CO₂ uptake capacity of up to 6.18 mmol g⁻¹ at 273 K and 101 kPa, and demonstrates high ratios of CO₂/CH₄ and CO₂/N₂ separation. From breakthrough and cycling experiments, M-DNL-6 demonstrates the ability to completely separate CO₂ from CH₄ or N₂ with a dynamic capacity of approximately 8.0 wt % before breakthrough. Importantly, the adsorbed CO₂ is easily released from the adsorbent through a simple gas purging operation at room temperature to regain 95 % of the original adsorption capacity. These results suggest that M-DNL-6 can be used as a potential adsorbent for CO₂ capture in pressure swing adsorption processes.

Supplementary Si, superior selectivity: DNL-6, which is an isomorphous crystal of the RHO zeolite with a silicoaluminophosphate (SAPO) composition, is synthesized with a high concentration of Si (4 Al) environments (M-DNL-6). This zeolite demonstrates efficient CO₂ adsorption and is shown to effectively separate CO₂ from CH₄ and N₂. It is also shown that M-DNL-6 can be regenerated under very mild conditions.

We studied the mechanism of the significant enhancement in the enzymatic saccharification of lignocelluloses at an elevated pH of 5.5–6.0. Four lignin residues with different sulfonic acid contents were isolated from enzymatic hydrolysis of lodgepole pine pretreated by either dilute acid (DA) or sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL). The adsorption isotherms of a commercial Trichoderma reesi cellulase cocktail (CTec2) produced by these lignin residues at 50 °C were measured in the pH range of 4.5–6.0. The zeta potentials of these lignin samples were also measured. We discovered that an elevated pH significantly increased the lignin surface charge (negative), which causes lignin to become more hydrophilic and reduces its coordination affinity to cellulase and, consequently, the nonspecific binding of cellulase. The decreased nonspecific cellulase binding to lignin is also attributed to enhanced electrostatic interactions at elevated pH through the increased negative charges of cellulase enzymes with low pI. The results validate the hypothesis that the increases in enzymatic saccharification efficiencies at elevated pH for different pretreated lignocelluloses are solely the result of decreased nonspecific cellulase binding to lignin. This study contradicts the well-established concept that the optimal pH is 4.8–5.0 for enzymatic hydrolysis using Trichoderma reesi cellulose, which is widely accepted and exclusively practiced in numerous laboratories throughout the world. Because an elevated pH can be easily implemented commercially without capital cost and with minimal operating cost, this study has both scientific importance and practical significance.

Phenomenon: We investigate the mechanism of the significant enhancement in the enzymatic saccharification of lignocelluloses at an elevated pH of 5.5–6.0. An elevated pH significantly increases the lignin surface charge, which causes lignin to become more hydrophilic and facilitates the electrostatic interactions between cellulose and lignin to reduce its coordination affinity to cellulase and, consequently, the nonspecific binding of cellulase.