Electronic structure modulation coupling with interface effect for great improving water electrolysis by multiple dimensional S doped MnCo2O4 nanorods/N doped C nanosheets hybrids

Abstract

The design of highly active, low cost and earth-abundant electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media are of great importance in practical water splitting. In this work, multiple dimensional hybrid catalysts were simply constructed by one-dimensional (1D) S-doped MnCo2O4 nanorods assembled by 0D nanoparticles composited with 2D N-doped carbon nanosheets derived from 3D chitosan carbon aerogel. Both the experimental and theoretical results confirmed that partially substitute of high-electronegative O with low-electronegative S can effectively regulate electron density of Co and Mn cations and strength of metal-O bonds, consequently, optimize the adsorption activity of active sites to reactants and the formation of reactive intermediates, change the rate-determining step and lower its energy barrier. The combined N-doped carbon nanosheets and multiple dimensional structure provided interface effect, larger specific surface, exposed more active sites, improved the conductivity and hydrophily of the hybrids. All the above superiority endowed the hybrid catalyst greatly improved electrocatalytic activities in hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and overall water splitting with low overpotential of 180 and 258 mV for HER and OER, and 1.57 V of cell voltage for water electrolysis at 10 mA/cm2, respectively. This work provided a vivid example for rational fabricating high-performance bifunctional electrocatalysts by combined strategies of electronic structure modulation and morphology design.