Facile preparation and enhanced photocatalytic H2-production activity of Cu(OH)2 cluster modified TiO2

Abstract

Cu(OH)2 cluster-modified TiO2 (Cu(OH)2/TiO2) photocatalysts were prepared by a simple precipitation method using Degussa P25 TiO2 powder (P25) as a support and copper nitrate as a precursor. Low-power ultraviolet light emitting diodes (UV-LEDs) were used as the light source for a photocatalytic water splitting reaction. The prepared samples show especially high photocatalytic H2-production activity from aqueous solutions containing ethylene glycol as sacrificial reagent even without a Pt co-catalyst. The optimal Cu(OH)2 loading content was found to be 0.29 mol%, giving an H2-production rate of 3418 μmol h−1 g−1 with a quantum efficiency (QE) of 13.9%, which exceeded the rate on pure TiO2 by more than 205 times. This high photocatalytic H2-production activity is attributed to the presence of Cu(OH)2 clusters on the surface of the TiO2. The potential of Cu(OH)2/Cu (Cu(OH)2 + 2e− = Cu + 2OH−, Eo = −0.224 V) is slightly lower than conduction band (−0.26 V) of anatase TiO2, whilst being higher than the reduction potential of H+ (2H+ + 2e− = H2, Eo = −0.000 V), which favors the electron transfer from the CB of TiO2 to Cu(OH)2, and the reduction of H+, thus enhancing photocatalytic H2-production activity. This work not only shows a possibility for the utilization of low cost Cu(OH)2 clusters as a substitute for noble metals (such as Pt) in photocatalytic H2-production, but also for the first time exhibits a facile method for enhancing H2-production activity by using hydroxide as a co-catalyst .