Heterojunction photocatalysts formed by reduced graphene oxide derived from defective spent cathode carbon and ZnIn2S4 for boosting photocatalytic hydrogen evolution

In this study, reduced graphene oxide derived from spent cathode carbon (SCCRGO) is utilized to construct a heterojunction structure with ZnIn2S4 (ZIS) for water splitting. Due to the extra vacancies and doping ions in the SCC, SCCRGO has a higher activity than RGO derived from ordinary graphene. The density functional theory (DFT) results show that the introduction of SCCRGO narrows the bandgap and increases the electron density of the system. As a result, the SCCRGO/ZIS composite exhibits a hydrogen production rate of 872.45 μmol g−1 h−1, which is 3.0 and 1.3 times higher than that of the pure ZIS and RGO/ZIS composites prepared by natural flake graphite, respectively. This work provides new insights for cocatalyst modification as well as the high-value recycling of SCC.