Enhanced photocatalytic H2 evolution based on a Ti3C2/Zn0.7Cd0.3S/Fe2O3 Ohmic/S-scheme hybrid heterojunction with cascade 2D coupling interfaces

Herein, the metallic Ti3C2 nanosheets decorated 2D-2D Zn0.7Cd0.3S (ZCS)-Fe2O3 Ohmic/step-scheme (S-scheme) hybrid heterojunction with cascade 2D coupling interfaces was rationally synthesized by oil bath and hydrothermal methods. The construction of both S-scheme and Ohmic heterojunctions was identified via in-situ irradiation XPS (ISI XPS), Electron spin resonance (ESR) or ultraviolet photoelectron spectroscopy (UPS) experiments, which can greatly improve the photocatalytic H-2 evolution raction (HER) rate and stability. The H-2 evolution rates of ZCS/0.5 Ti3C2, ZCS/2 Fe2O3 and ZCS/0.5 Ti3C2/2 Fe2O3 were 1.91, 2.0 and 6.35 times higher than that of pure ZCS nanosheets (NSs), respectively. The optimized ternary composite exhibits a highest HER activity of 27.24 mmol g(-1)h(-1), with an apparent quantum efficiency of 20.92% at 450 nm. Meanwhile, the ternary photocatalyst still exhibited much higher stability. Clearly, the strong S-scheme interfacial electric fields could effectively promote spatial charge separation between ZCS nanosheets and Fe2O3 nanosheets, while 2D Ti3C2 MXene nanosheets, as an Ohmic-junction H-2-evolution co-catalyst, could provide more electron transfer pathways and a large number of active sites for photocatalytic HER. It is expected that this work can offer some new idea or inspirations to rationally design highly efficient S-scheme heterojunction photocatalysts for further practical applications.

Automated summary

A hybrid heterojunction of metallic Ti3C2 nanosheets decorated 2D-2D Zn0.7Cd0.3S (ZCS)-Fe2O3 was synthesized to improve photocatalytic hydrogen evolution reaction (HER) rate and stability, achieving an optimized activity of 27.24 mmol g(-1)h(-1) with 20.92% apparent quantum efficiency at 450 nm. This work provides insights for designing efficient S-scheme heterojunction photocatalysts for practical applications.