Interfacial Electronic Interactions Between Ultrathin NiFe‐MOF Nanosheets and Ir Nanoparticles Heterojunctions Leading to Efficient Overall Water Splitting

Abstract Creating specific noble metal/metal‐organic framework (MOF) heterojunction nanostructures represents an effective strategy to promote water electrolysis but remains rather challenging. Herein, a heterojunction electrocatalyst is developed by growing Ir nanoparticles on ultrathin NiFe‐MOF nanosheets supported by nickel foam (NF) via a readily accessible solvothermal approach and subsequent redox strategy. Because of the electronic interactions between Ir nanoparticles and NiFe‐MOF nanosheets, the optimized Ir@NiFe‐MOF/NF catalyst exhibits exceptional bifunctional performance for the hydrogen evolution reaction (HER) (η 10 = 15 mV, η denotes the overpotential) and oxygen evolution reaction (OER) (η 10 = 213 mV) in 1.0 m KOH solution, superior to commercial and recently reported electrocatalysts. Density functional theory calculations are used to further investigate the electronic interactions between Ir nanoparticles and NiFe‐MOF nanosheets, shedding light on the mechanisms behind the enhanced HER and OER performance. This work details a promising approach for the design and development of efficient electrocatalysts for overall water splitting.


Figure S6 .
Figure S6.The EDS mapping and the corresponding EDS spectra of Ir@NiFe-MOF/NF.

Figure S18 .
Figure S18.The capacitive currents as a function of the scan rates (a).The double-layer capacitance (Cdl) values of different samples (b).

Figure S19 .
Figure S19.(a) the HER polarization curves of samples in the large-current ranges and (b) the overpotential comparison of Ir@NiFe-MOF/NF and Ir/NiFe-MOF/NF at various current densities.

Figure S20 .
Figure S20.The OER polarization curves of samples in the large-current ranges (a) and the overpotential comparison of Ir@NiFe-MOF/NF and Ir/NiFe-MOF/NF at various current densities (b).

Figure S22 .
Figure S22.Nyquist plots measured at the potential of (a, b) -30 mV for HER and (c) 1.53 V for OER in 1.0 M KOH.

Figure S23 .
Figure S23.The LSV curves of Ir@NiFe-MOF/NF before and after (a) HER and (b) OER tests.

Figure S24 .
Figure S24.The i-t curves of Ir@NiFe-MOF/NF with 1.6 V toward overall water splitting.

Figure S28 .
Figure S28.The EDS spectra of Ir@NiFe-MOF/NF after (a) HER and (b) OER in 1 M KOH.

Figure S31 .
Figure S31.The DOS plots for Ir NPs, NiFe-MOF and Ir@NiFe-MOF.The dashed line indicates the Fermi level for each system.

Figure S32 .
Figure S32.The optimized adsorption structures of HER and OER process intermediates at Ir NPs.

Figure S33 .
Figure S33.The optimized adsorption structures of HER and OER process intermediates at NiFe-MOF.

Figure S34 .
Figure S34.The optimized adsorption structures of HER and OER process intermediates at Ir@NiFe-MOF.

Figure S35 .
Figure S35.The optimized adsorption structures of OER process intermediates at NiFeOOH.

Figure S36 .
Figure S36.The optimized adsorption structures of OER process intermediates at Ir@NiFeOOH.