Hydrogen evolution over N-doped CoS2 nanosheets enhanced by superaerophobicity and electronic modulation

Abstract

Doping heteroatoms offers an opportunity to tune the electronic structure and promote hydrogen evolution reaction (HER) activity for an electrocatalyst. Herein, N-doped CoS2 nanosheets (N-CoS2 NSs) were deposited on carbon cloth via a hydrothermal and post-sulfuration process. The N-CoS2 NSs intercrossed with each other, exhibiting promising superaerophobicity without any adhesion to underwater bubbles. XPS analyses revealed the presence of electron transfer from Co to N dopant in N-CoS2, further proved by differential charge density and Bader charge analyses of density functional theory calculations. The electron transfer intrinsically altered the electronic structure of N-CoS2 and decreased the Gibbs adsorption energy of hydrogen over Co sites. The metallicity of CoS2 was remained after N doping, ascertaining a fast charge transfer and favorable HER process. The N-CoS2/CC showed an enhanced electrocatalytic HER activity with a Tafel slope of 60.1 mV dec−1 and low overpotential of 112 mV at a current density of 10 mA cm−2. Such promising performance is ascribed to the weak hydrogen adsorption upon N doping as well as the underwater superaerophobicity of N-CoS2/CC electrode. Our work might shed light on designing efficient and inexpensive HER electrocatalysts by tailoring their electronic structure and surface superaerophobicity.