Selenium vacancy-rich and heteroatom-doped CoSe/Mo₂CT_x MXene prepared using ionic liquid dopants for pH-universal hydrogen evolution and flexible supercapacitors

Vacancy engineering is a useful methodology in the development of catalysts and electrode materials. Herein, we report the introduction of Se-vacancy pairs in heteroatom-doped (N, B, and F) CoSe/Mo2CTx MXene (NBF-CoSe/Mo2CTx) to enhance the hydrogen evolution reaction (HER) and supercapacitor activities via an ionic liquid-mediated method. Se vacancy pairs and heteroatom doping enable the reallocation of local electron states and add active sites, improving the electrochemical activity of NBF-CoSe/ Mo2CTx with high HER activities over a broad range of pH. At a current density of 10 mA cm(-2), over voltages of 70 and 81 mV are respectively produced in 0.5 M H2SO4 and 1 M KOH. The optimal structure also exhibits outstanding electrochemical performance in an asymmetric supercapacitor with an energy density of 34.2 Wh kg(-1) at a power density of 15989.6 W kg-1. This study opens new avenues for the introduction of Se vacancies and heteroatom doping to improve the application performance. (c) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.