The electrochemical overall water splitting promoted by MoS2 in coupled nickel–iron (oxy)hydride/molybdenum sulfide/graphene composite

Abstract

Developing cost-effective methodologies for fabricating efficient bifunctional electrocatalysts is pivotal to boost electrochemical water splitting. Herein, we report an integrated composite, which is composed of NiFeOx(OH)y nanoparticles and vertically-oriented MoS2 nanosheets on reduced graphene oxide (rGO) matrix (NiFeOx(OH)y@MoS2/rGO), for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). It has been deduced that MoS2 is oxidized during OER, and the oxidized Mo species modulate the electronic structure of NiFeOx(OH)y to facilitate chemisorption of the oxygen species in OER. Meanwhile, NiFeOx(OH)y speeds up sluggish water dissociation in HER, and thus significantly improving HER activity of MoS2 in alkaline electrolyte. The integrated composite shows high electrocatalytic activity and superior durability for HER and OER with low overpotentials of 170 mV at 10 mA cm−2 and 250 mV at 20 mA cm−2, respectively. This work provides new approaches to develop electrocatalysts for overall water splitting and other applications.