FeNiSx@MoS2 Heterostructure: A Bioinspired Nonprecious Electrocatalyst for the Hydrogen Evolution Reaction in Acidic and Basic Media

Abstract FeNiS x @MoS 2 (INSMS) heterostructure is designed and developed to achieve a structural and functional analogue with biological enzyme active sites that catalyze hydrogen production. A two‐step synthetic method is applied to develop the heterostructure. As‐prepared INSMS integrates FeNiS x (INS) nanosheets on the surface of the MoS 2 nanopetals. The electrocatalyst demonstrates robust hydrogen evolution reaction (HER) activity due to the selective decoration of INS nanosheets over MoS 2 , owing to their different solubility product values. Two different phases of INS nanosheets are formed in INSNS due to the topotactic transition of INS nanosheets, as confirmed by the XRD and HR‐TEM analysis. In the HER, INSMS requires overpotentials of 110 and 155 mV at 10 mA cm −2 with Tafel slope values of 34 and 93 mV dec −1 in acidic and alkaline medium, respectively. This improved electrochemical performance is generated by the modification of the electron‐hole separation at the heterostructure interface and interlinked active edge sites at the interface.