Interface-engineered Co ₃ S ₄ /CoMo ₂ S ₄ nanosheets as efficient bifunctional electrocatalysts for alkaline overall water splitting

Abstract

Abstract Exploring bifunctional electrocatalysts with high efficiency, inexpensive, and easy integration is still the daunt challenge for the production of hydrogen on a large scale by means of water electrolysis. In this work, a novel free-standing Co 3 S 4 /CoMo 2 S 4 heterostructure on nickel foam by a facial hydrothermal method is demonstrated to be an effective bifunctional electrocatalyst for overall water splitting (OWS). The synthesized Co 3 S 4 /CoMo 2 S 4 electrocatalyst achieves ultralow overpotentials of 143 mV@10 mA cm −2 for hydrogen evolution reaction (HER) and 221 mV@25 mA cm −2 for oxygen evolution reaction (OER), respectively, in 1 M KOH. Moreover, it presents a greatly improved durability and stability under operando electrochemical conditions. When used as catalysts for OWS, the Co 3 S 4 /CoMo 2 S 4 -3//Co 3 S 4 /CoMo 2 S 4 -3 electrodes just need 1.514 V to make it to the current density of 10 mA cm −2 . It is supposed that the introduction of heterogeneous interface between Co 3 S 4 and CoMo 2 S 4 could give rise to plentiful active sites and enhanced conductivity, and thus boost excellent catalytic performances. Moreover, the porous feature of free-standing nanosheets on nickel foam could benefits catalytic performances by accelerating charge transport and releasing bubbles rapidly. This work proposes a bifunctional catalyst system with the heterogeneous interface, which could be used in a sustainable green energy system.