Study on optimization of photocatalyst Cu/TiO2 and catalytic hydrogen production performance

This study synthesized photocatalysts Cu/TiO 2 with various Cu loadings via a simple impregnation method and systematically characterized their structural, morphological, and optical properties. The photocatalytic hydrogen production performance was assessed under both laboratory xenon lamp irradiation and outdoor solar irradiation. The results show that the 3 wt%Cu/TiO 2 catalyst exhibits a reduced band gap of 3.11 eV (compared with 3.34 eV for pure TiO 2 ) and the lowest photogenerated electron-hole recombination rate, thus delivering the optimal catalytic performance. Under xenon lamp irradiation (light intensity of 450  mW cm −2 ) without external temperature control, the Cu/TiO 2 achieved a hydrogen production rate of 23.84 mmol g −1  h −1 . And the 3 wt%Cu/TiO 2 retained 87.13% of the hydrogen production rate after four consecutive 20 h cycles, indicating outstanding stability. However, when the light intensity was reduced to 350  mW cm −2 and the reaction temperature was maintained at 20 °C, the hydrogen production rate of 3 wt%Cu/TiO 2 decreased to 1.01 mmol g −1  h −1 , yet it remained 109 times higher than that of TiO 2 (0.01 mmol g −1  h −1 ). It is evident that increasing the light intensity can significantly enhance the hydrogen production rate of 3 wt%Cu/TiO 2 , whereas decreasing the temperature leads to a sharp decline in the hydrogen production rate. Furthermore, under outdoor solar irradiation (76.9  mW cm −2 ), the 3 wt%Cu/TiO 2 achieved a hydrogen production rate of 1.60 mmol g −1  h −1 . Under concentrated solar irradiation (202  mW cm −2 ), the rate further increased to 5.00 mmol g −1  h −1 .