Photocatalytic Hydrogen Production from Water and Biofuels: Current Status and Future Directions
Dr Geoff Waterhouse
School of Chemical Sciences University of Auckland
Time & Place
Fri, 19 Aug 2016 14:00:00 NZST in Rutherford Room 531
All are welcome
This talk will overview our recent research aimed at the development efficient semiconductor photocatalysts for hydrogen production from water and biofuels, focusing particularly on the performance optimization of M/TiO2 photocatalysts (M = Ni, Ag, Pd, PdAu and Pt) based on Evonik P25 for hydrogen production in alcohol-water mixtures under UV excitation (365 nm, 5 mWcm-2 ). Emphasis is placed on the roles of the metal co-catalyst and reaction medium on the rate of hydrogen evolution. H2 production rates were found to be dependent on (i) the metal co-catalyst; (ii) the co-catalyst loading; (iii) the alcohol type and (iv) the alcohol concentration. Co-catalyst activity at a total metal loading of 0.5 wt.% followed the general order PdAu > Pd ~ Pt > NiAu > Ni > Au >> Ag in most alcohol-water systems tested (10 vol.% alcohol). Results can be rationalised in terms of the relative work functions and the d-band center position of the different metals and metal alloys, with volcano curves established between H2 production rates and d-band centre position. The highest H2 production rate realised was for a 0.13Pd-0.25Au/TiO2 photocatalyst in 10 vol.% glycerol (60.3 mmol g-1 h-1 ). For each M/TiO2 photocatalyst in 10 vol.% alcohol, H2 production rates decreased in the order glycerol > 1,2-ethanediol > 1,2- propanediol > methanol > ethanol > 2-propanol > tertbutanol >> water. The optimum alcohol concentration was approximately 10, 20, 40 and 80 vol.% for glycerol, ethylene glycol, methanol and ethanol, respectively. Alcohol oxidizability and a low viscosity of the reaction medium are thus important to achieving high H2 production rates. Results conclusively identify Ni/TiO2 as a very promising alternative to Pd, Au or Pt-based photocatalysts for solar hydrogen production in alcohol-water systems. The potential of exploiting plasmonics and graphitic carbon-nitride (g-C3N4) for future solar hydrogen production is also discussed.
1) V. Jovic, K.E. Smith, H. Idriss, G.I.N. Waterhouse, ChemSusChem (2015), 8, 2551-2559.
2) W-T. Chen, A. Chan, Z.H.N. Al-Azri, A.G. Dosado, Aubrey G.; M.A. Nadeem, D. Sun-Waterhouse, H. Idriss, G.I.N. Waterhouse, Journal of Catalysis (2015), 329, 499-513.
3) W.T. Chen, A. Chan, D. Sun-Waterhouse, T. Moriga, H. Idriss, G.I.N. Waterhouse, Journal of Catalysis (2015), 326, 43-53.
4) Z.H.N. Al-Azri, W-T. Chen, A. Chan, V. Jovic, T. Ina, H. Idriss, G.I.N. Waterhouse, Journal of Catalysis (2015), 329, 355-3674.
5) H. Yu, L. Shang, T. Bian, R. Shi, G.I.N. Waterhouse, Y. Zhao, C. Zhou, L-Z. Wu, C.H. Tung, T. Zhang, Advanced Materials (2016), 28, 5080-5086.