The ability to use light to drive chemical reactions has led to applications in a wide range of fields, many contributing to improved life quality. In particular semiconductor photocatalysis has been applied to water splitting and hydrogen gas production,1 the destruction of micro-organisms such as bacteria and viruses2, 3 self cleaning surfaces4 as well as a wide range of environmental challenges such as improving water and air quality.5 Semiconductor Photocatalysis is an area of ever increasing importance in a diverse range of science and engineering subjects, with growing numbers of publications in press year on year.6

This In Focus brings together three research articles dealing with photocatalysis that were originally presented at SCI Photocatalysis 2010 held at University College London on September 23rd 2010.

The first paper by P.K.J. Robertson et al.7 reviews photocatalytic reactors for use in environmental remediation. The paper highlights the importance of photocatalytic reactor design in order to maximise mass transfer of pollutants to the catalyst surface as well as maximising catalyst illumination and optimising catalyst loading to maximise reactor efficiency. The review discusses the benefits and limitations of all of the well-known photocatlytic reactor types from packed bed to swirl flow reactors and beyond with regard to the treatment of waste water and the removal of volatile organic compounds from air. The review also discusses recent work conducted on the photocatalytic conversion of carbon dioxide in air to useful fuel products.8

M.J. Rosseinsky et al.9 describe the effect of platinum on the photocatalytic performance of nanoparticulate tungsten trioxide for the visible light photo-oxidation of methyl orange and isopropyl alcohol. Tungsten trioxide is a better candidate for visible light photocatalysis than titanium dioxide due to its narrower band gap of 2.6 eV rather than 3.2 eV. The authors report that the addition of platinum is critical to improving the visible light catalytic performance of the nanocrystalline samples due to charge separation effects and that an oxygen reduction rate of up to 75 × 10−9 mol s−1 could be achieved.

The final paper by T.A. Egerton10 asks, does photoelectrocatalysis by TiO2 work? The paper examines photoelectrocatalysis by titanium dioxide. The process aims to increase the efficiency of photocatalysis by applying a potential to the catalytic material, thus aiding UV induced charge carrier separation and preventing recombination, which typically limits the efficiency of conventional photocatalytic processes. The paper reports that photoelectrocatalysis operates at faster rates than conventional photocatalysis for a wide range of pollutants but is currently limited by the efficiency of catalysts' UV absorption behaviour.

I wish to thank all of the authors who contributed to this In Focus—Photocatalysis issue. I am also grateful to the editors of this journal, in particular Dr Peter Hambleton for his invaluable assistance and guidance.


  1. Top of page
  • 1
    Borogarello E, Kiwi J, Pelizzetti E, Visca M and Gratzel M, Photochemical Cleavage of Water by Photocatalysis. Nature 289: 158160 (1981).
  • 2
    Sjogren JC and Sierka RA, Inactivation of phage ms2 by iron-aided titanium dioxide photocatalysis. Appl Environ Microb 60: 344347 (1994).
  • 3
    Page K, Palgrave RG, Parkin IP, Wilson M, Savin-Shelley LP and Chadwick AV. Titania and silver-titania composite films on glass-potent antimicrobial coatings. J Mater Chem 17: 95104 (2007).
  • 4
    Smith S, Windows that clean themselves. Chem Rev 12: 3133 (2002).
  • 5
    OllisDF, Al-EkhabiH. Eds, Photocatlaytic purification and treatment of water and air. Elsevier, Amsterdam, the Netherlands (1993).
  • 6
    Mills A and Le Hunte S, An overview of semiconductor photocatalysis. J Photoch Photobio A 108: 135 (1997).
  • 7
    McCullagh C, Skillen N, Adams M and Robertson PKJ, Photocatalytic reactors for environmental remediation: a review. J Chem Technol Biotechnol 86: 10021017 (2011).
  • 8
    Lo C-C, Hung C-H, Yuan C-S and Wu J-F, Photoreduction of carbon dioxide with H2 and H2O over TiO2 and ZnO in a circulated photocatalytic reactor. Sol Energ Mat Sol C 91: 17651774 (2007).
  • 9
    Joshi UA, Darwent JR, Yiu HHP and Rosseinsky MJ, The effect of platinum on the performance of WO3 nanocrystal photocatalysts for the oxidation of Methyl Orange and iso-propanol. J Chem Technol Biotechnol 86: 10181023 (2011).
  • 10
    Egerton TA, Does photoelectrocatalysis by TiO2 work? J Chem Technol Biotechnol 86: 10241031 (2011).