A novel core–double shell heterostructure derived from a metal–organic framework for efficient HER, OER and ORR electrocatalysis

Abstract

The hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are the cornerstone reactions of renewable energy technologies, like electrochemical water splitting and metal–air batteries. To promote these reactions, robust and efficient catalysts are highly desired. However, developing multifunctional electrocatalysts for integrating the HER, OER and ORR into one electrode still remains a huge challenge. Constructing intriguing nanostructures with multiple components and hierarchical interfaces could be an efficient method to develop multifunctional electrocatalysts. Herein, we report a strategy, derived from ZIF-67, to synthesize a novel core–double shell heterostructure Co₉S₈@Co₉S₈@MoS₂-0.5 as a trifunctional pre-catalyst for the HER, OER and ORR. Firstly, a core–shell Co@Co₉S₈ precursor was prepared through sulfurization and pyrolysis of ZIF-67. Then, a hydrothermal method was adopted to grow MoS₂ on the Co@Co₉S₈ precursor. Such a synthetic strategy endows the heterostructure with a strong interface effect that affects the electronic structure of materials and further boosts their electrocatalytic performance. The obtained Co₉S₈@Co₉S₈@MoS₂-0.5 heterostructure shows outstanding electrochemical performance. The overpotentials required for the HER and OER in an alkaline solution are 173 mV and 340 mV at 10 mA cm⁻², respectively. Moreover, Co₉S₈@Co₉S₈@MoS₂-0.5 also exhibits superior ORR performance with a half-wave potential of 0.77 V. The strategy described here can be extended to a number of integrated multifunctional electrocatalysts for water splitting and metal–air batteries.