Interface engineering of (Ni, Fe)S2@MoS2 heterostructures for synergetic electrochemical water splitting

Abstract Water splitting to generate hydrogen is a promising and sustainable process, whereas is limited by the large overpotential of electrode materials for cathode hydrogen evolution reaction (HER) and anode oxygen evolution reaction (OER). Here we present an interface engineering strategy to construct efficient bifunctional electrocatalyst based on (Ni, Fe)S2@MoS2 heterostructrues for water-splitting process. The as-prepared (Ni, Fe)S2@MoS2 catalyst gives remarkable electrochemical activity and durability under alkaline environments, with a low overpotential of 130 mV for HER and 270 mV for OER to deliver the current density of 10 mA cm−2, respectively. In combination with in-situ Raman spectra, we demonstrate that the constructed interfacial active sites are favorable to the formation of S-Hads, which synergistically lower the chemisorption energy of the intermediates of HER and OER, thereby facilitating the electrocatalytic overall water splitting. Furthermore, we regulate the interface of (Ni, Fe)S2@MoS2 and electrolyte through changing the composition of electrolyte to achieve much longer electrochemical stability of this hybrid sulfide electrocatalyst.