Surface hydroxyl groups of TiO2/CuO/Cu heterostructure enhances photocatalytic hydrogen production

This study employed a simple low-temperature hydrothermal and sintering method to prepare TiO 2 (referred as T) heterostructure with different surface hydroxyl concentrations. Auger analysis indicated the binding energy peaks at 565 eV and 570 eV were corresponded to Cu 2+ and Cu 0 , respectively, which proved that the heterostructure was TiO 2 /CuO/Cu (referred as TC). Meantime, XPS and FTIR indicated that altering the calcination temperature was beneficial for controlling the proportion of surface hydroxyl groups (-OH). Among the samples, TC calcined at 300 °C (denoted as TC-300 °C) exhibited the highest photocatalytic performance, delivering an H 2 evolution rate of 182.68 μmol g −1  h −1 , which is 3.3 times and 1.9 times higher than those of T and the uncalcined TC sample, respectively. DFT calculations showed that the rate-determining step of the oxygen evolution reaction (OER) occurred at the *OH adsorption step. By comparing different hydroxyl adsorption sites on TiO 2 , CuO, and Cu, it was confirmed that hydroxyl groups adsorbed near Ti atoms were more favorable for improving catalytic activity. Additionally, the electron transfer process in TiO 2 /CuO/Cu heterostructure was proposed. This provided insights for the preparation of highly efficient catalysts that can promote photocatalytic water splitting half-reactions and improve hydrogen production efficiency.