Interfacial Electronic Modulation of Mo<sub>5</sub>N<sub>6</sub>/Ni<sub>3</sub>S<sub>2</sub> Heterojunction Array Boosts Electrocatalytic Alkaline Overall Water Splitting
Bin Fang, Jutao Jin, Yanqin Li, Haifeng Dang, Mengmeng Shao, Liyuan Zhao, Nianliang Yin, Wenlong Wang
Abstract
Abstract Bifunctional electrocatalysts with excellent activity and durability are highly desirable for alkaline overall water splitting, yet remain a significant challenge. In this contribution, palm‐like Mo 5 N 6 /Ni 3 S 2 heterojunction arrays anchored in conductive Ni foam (denoted as Mo 5 N 6 ‐Ni 3 S 2 HNPs/NF) are developed. Benefiting from the optimized electronic structure configuration, hierarchical branched structure and abundant heterogeneous interfaces, the as‐synthesized Mo 5 N 6 ‐Ni 3 S 2 HNPs/NF electrode exhibits remarkably stable bifunctional electrocatalytic activity in 1 m KOH solution. It only requires ultralow overpotentials of 59 and 190 mV to deliver a current density of 10 mA cm −2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 m KOH solution, respectively. Importantly, the overall water splitting electrolyzer assembled by Mo 5 N 6 ‐Ni 3 S 2 HNPs/NF exhibits an exceptionally low cell voltage (1.48 V@10 mA cm −2 ) and outstanding durability, surpassing most of the reported Ni‐based bifunctional materials. Density functional theory (DFT) further confirms the heterostructure can optimize the Gibbs free energies of H and O‐containing intermediates (OH, O, OOH) during HER and OER processes, thereby accelerating the catalytic kinetics of electrochemical water splitting. The findings provide a new design strategy toward low‐cost and excellent catalysts for overall water splitting.