SnO2 -TiO2 structures and the effect of CuO, CoO metal oxide on photocatalytic hydrogen production

Abstract

BACKGROUND The technology for generating hydrogen using a photocatalyst has attracted considerable attention. Coupling TiO2 with other semiconductor oxides provided excellent results in decreasing recombination by transferring one of the charge carriers to another oxide. These photogenerated charge carriers play key roles in the reduction and oxidation process in photocatalytic hydrogen production. Nevertheless, even if the (e−-h+) are separated, the reaction cannot happen without proper active sites. So, co-catalysts are needed to improve the reduction and oxidation process on the surface of photocatalyst. RESULTS The hydrogen production of SnO2@TiO2 structure with CuO and CoO co-catalysts (1 wt% of co-catalyst: 1Co-ST, 1Cu-ST and 1Co-1Cu-ST) was studied under UV light, and characterized by XRD, N2 adsorption, UV-vis reflectance diffuse, XPS and photoelectrochemical test. The dispersion of co-catalyst on the surface of ST material during impregnation generates a decrease in the surface area and defect states in the optical properties. Maximum hydrogen production rate 1486.4 µmol g−1 h−1 is observed on 1Co-1Cu-ST photocatalyst. This improvement in photocatalytic reaction is related to the role played by each co-catalyst. CONCLUSIONS The photocatalytic activity for H2 evolution shows the role of co-catalyst in the redox reactions process. In the case of CuO co-catalyst, it helps charge transfer, specifically electrons, to be carried out more efficiently by reducing water to produce H2. On the other hand, the role of CoO co-catalyst is to catalyze the oxidation process, improving charge carriers separation and providing electrons to the SnO2@TiO2. © 2017 Society of Chemical Industry