He+ beam irradiation boosting electrocatalytic performance of NiS2 nanosheets for hydrogen evolution reaction

Abstract

Hydrogen evolution by water splitting is one of the most popular methods in the new generation energy exploration. During the hydrogen evolution reaction (HER), NiS₂, which is an electrochemical catalyst, has been widely investigated. However, the electrochemical catalytic performance of NiS₂-based catalysts is still dissatisfied due to their relatively poor intrinsic catalytic activities. Herein, we introduced vacancies into NiS₂ nanosheets and the activation of initial inert sulfur sites by He⁺ ion irradiation (at a dose of 1 × 10¹⁵/cm²) to improve the HER electrocatalytic performance of NiS₂. Additionally, density functional theory (DFT) calculations were adopted. Clearly, the intrinsic vacancies (both Ni and S vacancies) of NiS₂ can reduce the band gap of NiS₂ and improve its electron transfer efficiency in the HER process. This work provides a candidate strategy for NiS₂-based electrocatalysts to optimize HER performance.