Dual-Vacancies Confined in Nickel Phosphosulphide Nanosheets Enabling Robust Overall Water Splitting.

Exploring highly efficient electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance for confronting the energy and environmental crisis. Vacancies engineering has been regarded as a promising way to optimize the catalytic activity of electrocatalysts. Herein, we put forward a conceptually new dual Ni, S-vacancies engineering on 2D NiPS3 nanosheet (denoted as V-NiPS3 Ns) by a simple ball-milling treatment with ultrasonication. This material presents an ideal model for exploring the role of dual vacancies in improving the catalytic activity for overall water splitting. Structural analyses make clear that the formation of dual Ni, S-vacancies regulates the electronic structure and catalytic active sites of NiPS3 nanosheet, leading to the superior HER/OER performance. A smaller overpotential of 124 mV and 290 mV can be achieved at the current density of 10 mA cm-2 for HER and OER, respectively. It is worth noting that the OER performance of V-NiPS3 is the best value among all state-of-the-art NiPS3 catalysts. In addition, the assembled two-electrode cell by V-NiPS3 exhibits enhanced catalytic performance with the low cell voltages of 1.60 V at 10 mA cm-2. This work offers a promising avenue to improve the electrocatalytic performance of the catalysts by engineering dual vacancies for large-scale water splitting.