Interface-engineered Co₃S₄/CoMo₂S₄nanosheets as efficient bifunctional electrocatalysts for alkaline overall water...

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 Co₃S₄/CoMo₂S₄heterostructure on nickel foam by a facial hydrothermal method is demonstrated to be an effective bifunctional electrocatalyst for overall water splitting (OWS). The synthesized Co₃S₄/CoMo₂S₄electrocatalyst achieves ultralow overpotentials of 143 mV@10 mA cm^-2for hydrogen evolution reaction (HER) and 221 mV@25 mA cm^-2for 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 Co₃S₄/CoMo₂S₄-3//Co₃S₄/CoMo₂S₄-3 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 Co₃S₄and CoMo₂S₄could 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.