Effect of alcohol sacrificial agent on the performance of Cu/TiO2 photocatalysts for UV-driven hydrogen production

Abstract This study systematically investigates alcohol photoreforming over a 1 wt.% Cu/TiO2 photocatalyst under UV excitation (365 nm, 6.5 mW cm-2), examining the effects of the alcohol (methanol, ethanol, ethylene glycol or glycerol) and alcohol concentration (0-100 vol.%) on H2 production rates. A 1.25 wt.% CuO/TiO2 photocatalyst, based on Evonik P25, was first synthesized. Various in-situ spectroscopic methods, including Cu K-edge XANES, UV-vis absorbance spectroscopy and EPR spectroscopy, confirmed the reduction of the supported CuO to Cu° during alcohol photoreforming. The 1 wt.% Cu/TiO2 photocatalyst formed in-situ demonstrated excellent activity for H2 production, comparable to a 2 wt.% Au/TiO2 reference photocatalyst. At an alcohol concentration of 10 vol.%, H2 production rates followed the order glycerol > ethylene glycol > methanol > ethanol. At 50 vol.%, the rates followed the order methanol > ethylene glycol > glycerol ≈ ethanol. The study highlights the potential of Cu° as a H2 evolution co-catalyst.