Unraveling structural properties of Cu₂O loaded on gC₃N₄ for enhanced photocatalytic hydrogen generation

In this study, we load Cu₂O into gC₃N₄ via an ultrasonic reduction method. By doing so, the steady-state electron population is increased by 3 times. Due to the revealed critical role of Cu₂O in enhancing the electron population in gC₃N₄, the structural features of the loaded Cu₂O are studied with synchrotron x-ray absorption spectroscopy (XAS), including x-ray absorption near edge spectroscopy (XANES) and extended x-ray absorption fine structure (EXAFS). Results show that the Cu species are present in +1 oxidation state in the form of nano-sized Cu₂O. Each Cu cation is approximately coordinated to 2 O anions with an average length of 1.85 Å. Loading 1 wt% of Cu₂O into gC₃N₄ generates H2 with a rate of 7.53 μmol/g centerdot h, which is more than 5-fold of bare gC₃N₄ (1.44 μmol/g centerdot h), under visible light irradiation in the presence of methanol as holes scavenger. The examined Cu₂O/gC₃N₄ shows appreciable stability within 5 cycles of H₂ generation.