A DFT study on the electrocatalytic water splitting performance of heterostructure Bi2S3/Ni3S2

The global environmental pollution issue is becoming increasingly severe, making the design of efficient and cost-effective bifunctional electrocatalysts an important and highly valuable area of research. This paper investigates the electrocatalytic performance of the Bi₂S₃/Ni₃S₂ heterostructure for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) using density functional theory (DFT). The catalytic performance for HER is evaluated by the change in Gibbs free energy of hydrogen atom adsorption on the catalyst surface (|∆G* H|), while the overpotential (η) is used to assess the catalytic performance for OER. The calculations reveal that the Bi₂S₃/Ni₃S₂ heterostructure exhibits a low overpotential of -0.098/0.85 V, outperforming the electrocatalytic performance of Ni₃S₂, making it a promising bifunctional electrocatalyst. By analyzing its electronic structure and charge transfer behavior, it is demonstrated that the enhanced catalytic performance is primarily attributed to the Bi₂S₃/Ni₃S₂ heterostructure, which contributes to high conductivity, a high density of states near the valence band maximum, and more stable H₂O adsorption. Furthermore, the effect of impurity atoms on the catalytic performance of Bi₂S₃/Ni₃S₂ is examined. The results indicate that doping Co into Ni₃S₂ enhances the electrocatalytic performance of the Bi₂S₃/Ni₃S₂ heterostructure.