Unlocking catalytically active sites in FeMnS/MXene@Ni(OH)2 arrays via heterojunction strategy for highly efficient overall water splitting

Abstract

Developing efficient and earth-abundant bifunctional electrocatalysts for water electrolysis remains a critical challenge due to sluggish reaction kinetics and limited structural durability. Herein, a FeMnS/Ti 3 C 2 T x @Ni(OH) 2 (NFMM) heterostructure is fabricated through the synergistic integration of FeMnS, MXene and Ni(OH) 2 . The work function mismatch between FeMnS and Ni(OH) 2 induces interfacial charge redistribution, creating a built-in electric field that optimizes the electronic structure of catalytic sites. Meanwhile, highly conductive MXene provide efficient charge transport pathways. Benefiting from these synergistic effects, NFMM exhibits low overpotentials of 135.4 mV for OER and 191.3 mV for HER at 10 mA cm −2 in alkaline media. Furthermore, the assembled NFMM||NFMM electrolyzer requires only 1.68 V to achieve 10 mA cm −2 and demonstrates excellent durability over 100 h at 100 mA cm −2 . Density functional theory simulations confirm enhanced electronic conductivity and charge migration in the heterostructure, demonstrating the remarkable catalytic performance of NFMM in promoting electrocatalytic reactions and enabling sustainable hydrogen production.