Nickel@Nitrogen-Doped Carbon@MoS2 Nanosheets: An Efficient Electrocatalyst for Hydrogen Evolution Reaction

Abstract

Developing cheap, abundant, and easily available electrocatalysts to drive the hydrogen evolution reaction (HER) at small overpotentials is an urgent demand of hydrogen production from water splitting. Molybdenum disulfide (MoS₂ ) based composites have emerged as competitive electrocatalysts for HER in recent years. Herein, nickel@nitrogen-doped carbon@MoS₂ nanosheets (Ni@NC@MoS₂ ) hybrid sub-microspheres are presented as HER catalyst. MoS₂ nanosheets with expanded interlayer spacings are vertically grown on nickel@nitrogen-doped carbon (Ni@NC) substrate to form Ni@NC@MoS₂ hierarchical sub-microspheres by a simple hydrothermal process. The formed Ni@NC@MoS₂ composites display excellent electrocatalytic activity for HER with an onset overpotential of 18 mV, a low overpotential of 82 mV at 10 mA cm^-2 , a small Tafel slope of 47.5 mV dec^-1 , and high durability in 0.5 H₂ SO₄ solution. The outstanding HER performance of the Ni@NC@MoS₂ catalyst can be ascribed to the synergistic effect of dense catalytic sites on MoS₂ nanosheets with exposed edges and expanded interlayer spacings, and the rapid electron transfer from Ni@NC substrate to MoS₂ nanosheets. The excellent Ni@NC@MoS₂ electrocatalyst promises potential application in practical hydrogen production, and the strategy reported here can also be extended to grow MoS₂ on other nitrogen-doped carbon encapsulated metal species for various applications.

Keywords: electrocatalysts; hierarchical sub-microspheres; hydrogen evolution reaction; molybdenum disulfide; nickel@nitrogen-doped carbon.