Strong redox-capable graphdiyne-based double S-scheme heterojunction 10%GC/Mo for enhanced photocatalytic hydrogen evolution

Abstract

Graphdiyne (GDY) is a new two-dimensional layered structure of carbon isomers composed of sp and sp2 hybridized carbon atoms, which has attracted much attention in many fields because of its unique energy band structure, stability and high carrier mobility. However, GDY has been rarely reported in the study of photocatalytic hydrogen precipitation. In this work, graphdiyne-CuI (GDY-CuI) was successfully prepared by cross-coupling method using Cu salt (CuI) instead of Cu foil. Based on the modulation of the energy band structure and redox ability of the photocatalyst, a typical S-scheme heterojunction was constructed by introducing MoO2 through in situ sonication and stirring, and the composite catalyst 10%GC/Mo exhibited step-like electron transfer and strong redox ability. Under the action of internal electric field, this unique heterojunction can induce rapid electron transfer in a directional manner, which effectively promotes the separation of photogenerated electrons and holes in MoO2, thus improving the photocatalytic hydrogen evolution performance. The photocatalytic hydrogen evolution rate of the composite photocatalyst 10%GC/Mo was 32.8 μmol (8 mg of catalyst acted for 5 h), which was 32 times that of primitive MoO2. The introduction of GDY-CuI accelerates the charge separation and transfer rate, prolongs the lifetime of photogenerated carriers, and reduces the reaction overpotential. This work provides a reference for the application of the novel two-dimensional photocatalytic materials GDY and GDY-CuI in the field of photocatalysis.