Pivotal role of oxygen during the synthesis of Cu(OH)2/TiO2 and its effect on photocatalytic hydrogen production activity

Abstract

Herein, we have demonstrated that the structural bonding of TiO2/Cu(OH)2 significantly changes in the presence of dissolved oxygen in water, and the photocatalytic activity directly depends on the interaction of surface species in TiO2. The Cu(OH)2/TiO2 nanostructured photocatalysts were prepared in the presence and absence of molecular oxygen. A remarkable finding of the work is that the sample prepared in the presence of oxygen produced 1169 µmol/g/h higher hydrogen than the sample prepared with nitrogen. The Cu(OH)2/TiO2 photocatalysts generated 27592 μmol/g and 22916 μmol/g of hydrogen in 4 h of reaction time under solar light irradiation for samples prepared in the presence and absence of molecular oxygen, respectively. Compared to the bare TiO2, a 60 folds enhancement in hydrogen production was observed for Cu(OH)2/TiO2, and it has been attributed to the formation of interface bonding between Cu(OH)2 and TiO2, the semi-amorphous nature of Cu(OH)2, the existence of terminal hydroxyl species on the TiO2 surface, and extended visible light absorption due to the d-d transition bands of Cu. This cost-effective and room temperature synthesis strategy provides new insight into manipulating the surface chemistry of TiO2-based photocatalysts for improved visible light absorption and charge transport dynamics.