Engineering Heterostructure of Bimetallic Nickel-Silver Sulfide as an Efficient Electrocatalyst for Overall Water Splitting in Alkaline Media

Abstract

Bimetallic composites have been widely utilized as high-active catalysts in electrochemical reactions due to the synergistic effect at the interfaces of the hybrid-boundaries. However, there are few reports on the application of bimetallic sulfides. Herein, a facile one-step strategy was designed and implemented to prepare the bimetallic nickel-silver sulfides with heterostructure as high-efficiency water electrolysis catalysts. The optimal Ag 2 S and NiS x combo-catalyst outputs activities towards both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). At 10 mA cm -2 , the overpotentials for OER and HER are 260 mV and 230 mV, respectively, which are even superior to those observed on Pt- and IrO 2 -/RuO 2 -based precious catalysts. On one hand, Ag 2 S/Ag doped in NiS x fascinates the electron transfer between the abundant interfaces, and on the other hand, hetero-doping also induces Ni species oxidation to NiOOH active intermediate for OER, thus accelerating the reaction rate. Therefore, the well-prepared bimetallic Ag 2 S-NiS x materials demonstrated higher synergistic catalytic activities for both OER and HER.

Keywords: Bimetallic sulfide, heterostructure, Synergistic effect, Oxygen evolution reaction (OER), Hydrogen evolution reaction (HER)