Impact of Cu oxidation state on photocatalytic H2 production by Cu/TiO2

This work focuses on the influence of Cu oxidation state on photocatalytic hydrogen generation by Cu/TiO₂·Hydrogen reduction was used to tailor the Cu oxidation state on the TiO_2.Cu⁺ and/or Cu⁰ appeared to be the more favourable oxidation state for generating H_2. Cu²⁺ initially present on the TiO₂ was reduced to Cu⁺ and/or Cu⁰ during the photocatalytic process. Cu deposits on reduced Cu/TiO₂ catalysts were observed to be metallic Cu with a thin shell of CuO and its activity was greater than both bare TiO₂ and air-calcined Cu/TiO₂. This enhancement could be attributed to metallic copper and improved Cu crystallinity.