Electrochemically exfoliated Ni-doped MoS2 nanosheets for highly efficient hydrogen evolution and Zn-H2O battery

Abstract

Thanks to tunable physical and chemical properties, two-dimensional (2D) materials have received intensive interest, endowing their excellent electrocatalytic performances for applications in energy conversion. However, their catalytic activities are largely determined by poor adsorption energy and limited active edge sites. Herein, a one-step electrochemical exfoliation strategy was developed to fabricate 2D Ni-doped MoS2 nanosheets (Ni-EX-MoS2) with a lateral size of ∼500 nm and thickness of ∼3.5 nm. Profiting from high electrical conductivity and abundant exposing active sites, Ni-EX-MoS2 catalyst displayed an admirable performance for electrochemical hydrogen evolution reaction (HER) with a low overpotential of 145 mV at 10 mA/cm2 as well as a small Tafel slope of 89 mV/dec in alkaline media, which are superior to those of the most reported MoS2-based electrocatalysts. The formed Ni species with tuning electronic structure played a crucial role as primary active center of Ni-EX-MoS2, as well as the forming stable 1T/2H phase MoS2 interface demonstrated a synergistic effect on electrocatalytic HER performance. Further, Ni-EX-MoS2 was employed as a cathode electrode for alkaline Zn-H2O battery, which displayed a high power density of 3.3 mW/cm2 with excellent stability. This work will provide a simple and effective guideline for design of electrochemically exfoliated transition metal-doped MoS2 nanosheets to inspire their practical applications in energy catalytic and storage.