Plasma Etching of Pyrite-Type Nickel Diselenide Nanosheets to Create Selenium Vacancies for Applications as Electrocatalysts for Hydrogen Evolution
Fangqing Wang, Yangyang Zhang, Wenhao Yuan, Jing Mao, Kai Wang, Ying Li, Cong Chen, Limin Liang, Caichi Liu
Abstract
Boosting the hydrogen evolution reaction (HER) process with highly efficient non-noble metal catalysts is crucial for hydrogen-powered fuel cells. Pyrite-type NiSe 2 is one of the most promising HER catalysts due to its inexpensive cost and good conductivity, although its intrinsic activity is moderate. Using a plasma etching method on a carbon cloth substrate material, we created a large number of selenium vacancies on NiSe 2 nanosheets (NiSe 2 -V Se /CC). With a low overpotential of 91 mV and a Tafel slope of 91 mV dec –1 at 10 mA cm –2, as well as a durability of 20 h at high current (100 mA cm –2 ), the NiSe 2 -V Se /CC demonstrates superior HER performance for its catalytic activity and long-term stability. Cross-validated by measurement analyses and density functional theory calculations, the introduction of vacancies reduces the resistivity of NiSe 2 and optimizes its hydrogen adsorption energy ( G H* ) and water adsorption energy ( G H2O* ). Based on defect engineering, this study proposes an approach to designing improved electrocatalysts for alkaline HER.