Construction of a transition-metal sulfide heterojunction photocatalyst driven by a built-in electric field for efficient hydrogen evolution under visible light

Photocatalytic H-2 evolution is of prime importance in the energy crisis and in lessening environmental pollution. Adopting a single semiconductor as a photocatalyst remains a formidable challenge. However, the construction of an S-scheme heterojunction is a promising method for efficient water splitting. In this work, CdS nanoparticles were loaded onto NiS nanosheets to form CdS/NiS nanocomposites using hollow Ni(OH)(2) as a precursor. The differences in the Fermi energy levels between the two components of CdS and NiS resulted in the formation of a built-in electric field in the nanocomposite. Density functional theory (DFT) calculations reveal that the S-scheme charge transfer driven by the built-in electric field can accelerate the effective separation of photogenerated carriers, which is conducive to efficient photocatalytic hydrogen evolution. The hydrogen evolution rate of the optimized photocatalyst is 39.68 mmol.g(-1) h(-1), which is 6.69 times that of CdS under visible light. This work provides a novel strategy to construct effective photocatalysts to relieve the environmental and energy crisis.

Automated summary

Photocatalytic H-2 evolution is crucial in addressing the energy crisis and reducing environmental pollution. Constructing an S-scheme heterojunction is a promising approach, but using a single semiconductor as a photocatalyst is challenging. In this study, CdS nanoparticles were loaded onto NiS nanosheets to form CdS/NiS nanocomposites. The formation of a built-in electric field in the nanocomposite, due to the differences in Fermi energy levels between CdS and NiS, was found to accelerate the effective separation of photogenerated carriers, leading to efficient photocatalytic hydrogen evolution. The optimized photocatalyst exhibited a hydrogen evolution rate that is 6.69 times higher than that of CdS under visible light. This research provides a novel strategy for constructing effective photocatalysts to tackle the environmental and energy crisis.