Oxygen vacancies in concave cubes Cu₂O-reduced graphene oxide heterojunction with enhanced photocatalytic H₂ production

A novel composite heterojunction based on concave cubes Cu₂O-reduced graphene oxide (Cu₂O-RGO) was synthesized via one-pot hydrothermal method. The anionic surfactant dioctyl sulfosuccinate sodium salt (AOT) can act as the soft template to build the novel Cu₂O-based microstructure. The ascorbic acid serves as reductant and etching agent in the Cu₂O growing process. The facet etching of Cu₂O and reduction of GO can take place simultaneously in the reaction system. The concave cubes Cu₂O with average edge length of ~ 1.55 µm were well-dispersed on the surface of RGO. The Cu₂O-RGO (2 wt%) heterojunction exhibited superior photocatalytic performance and recyclability with the highest amount of H₂ yields of 64.3 µmol/g, which was fivefold more than the pure Cu₂O (12.8 µmol/g). The enhanced photocatalytic performances were attributed to the oxygen vacancies in Cu₂O and a flexible conducting channel supported by RGO. Furthermore, the synergistic effect of Cu₂O and graphene caused broader absorption in visible light region and lower recombination of photogenerated electron–hole pairs. It is believed that the Cu₂O-RGO heterojunction could provide an alternative method to design excellent photocatalysts for energy application.