CoNi2S4@CoNi-LDH heterojunction grown on SSM as a highly efficient trifunctional catalyst for water-splitting and Zn–air batteries

Abstract

The development of self-supported trifunctional catalysts for Zn–air batteries (ZABs) and efficient water splitting is of great significance. Herein, we have directly sulfurized cobalt nickel-layered double hydroxides (CoNi-LDH) grown in situ on stainless steel mesh (SSM) and successfully obtained CoNi₂S₄@CoNi-LDH/SSM, which needs only 252 mV to achieve a current density of 10 mA cm⁻² for the oxygen evolution reaction (OER), and a 0.74 V half-wave potential for the oxygen reduction reaction (ORR). Moreover, it shows enhanced hydrogen evolution reaction (HER) activity as compared to the precursor. Also, when serving as an air-cathode in the assembly of the liquid Zn–air battery (ZAB), it delivers a charge and discharge cycle of 320 hours and a voltage gap of 0.78 V at 5 mA cm⁻². All the electrocatalytic properties of CoNi₂S₄@CoNi-LDH/SSM are superior to the precursor, CoNi-LDH/SSM. Further vulcanization formed the heterojunction of CoNi₂S₄@CoNi-LDH and resulted in the obtained CoNi₂S₄@CoNi-LDH/SSM, which is an outstanding trifunctional catalyst. This study provides an experimental foundation and design inspiration for other self-supported trifunctional catalysts.