The role of CuO in promoting photocatalytic hydrogen production over TiO2

Low cost semiconductor photocatalysts that can efficiently harvest solar energy to generate H-2 from water or biofuels will be critical to future hydrogen economies. In this study, low cost CuO/TiO2 photocatalysts (CuO loadings 0-15 wt.%) were prepared, characterized and evaluated for H-2 production from ethanol water mixtures (80 vol.% ethanol, 20 vol.% H2O) under UV excitation. TEM, XRF, EDAX, EPR, Raman, TGA, XPS and Cu L-edge NEXAFS data showed that at CuO loadings <5 wt.%, Cu(II) was highly dispersed over the TiO2 support, possibly as a sub-monolayer CuO species. At higher loadings, CuO crystallites of diameter 1-2 nm were identified. The photocatalytic activity of CuO/TiO2 photocatalysts was highly dependent on the CuO loading, with 1.25 wt.% CuO being optimal (H-2 production rate = 20.3 mmol g(-1) h(-1)). Results suggest that sub-monolayer coverages of Cu(II) or CuO on TiO2 are highly beneficial for H-2 generation from ethanol-water mixtures and support the development of a sustainable H-2 economy. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.