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.