Metal Organic Frameworks Derived Fe-Cof2/Mxene Composites as Efficient Electrocatalysts for the Overall Water Splitting

Abstract

Transition metal fluorides because of the high electronegativity of fluorine may enhance the local electron density of the metal sites and promote water molecule dissociation and charge transfer. However, enhancing the intrinsic activity of fluorides to improve material stability remains a challenge. Herein, we develop an innovative four-step synthetic strategy (electrochemical deposition → co-precipitation → ligand exchange → in situ fluorination) to engineer three-dimensional porous Fe-doped CoF2 nanocubes vertically anchored on MXene (Fe-CoF2/MXene/NF). The breakthrough lies in constructing a dynamically reconstructed heterostructure where Fe doping synergizes with MXene-induced electron redistribution, while the fluorination-induced etching crafts a hierarchically porous nanocubic architecture. This unique structure is characterized by the maximum electrochemical surface area of iron-cobalt dual active sites, accelerated charge transfer by MXene-derived conductive networks, and robust structural robustness. Remarkably, the optimized catalyst achieves low overpotentials for hydrogen evolution reaction (η10 = 121 mV) and oxygen evolution reaction (η10 = 207 mV), surpassing most reported transition metal fluorides. Notably, it enables efficient overall water splitting at an ultralow cell voltage of 1.52 V (10 mA cm-2) while maintaining 98% activity after 100-hour continuous operation. This work establishes a synergistic strategy to enhance catalytic activity by simultaneously modulating electronic configurations and accelerating charge transfer kinetics, achieved through rational structural design integrating organic framework derivatization, the coupling of metal doping with interfacial engineering.

Keywords: Transition Metal Fluorides, MXene, Bifunctional Electrocatalysis, Overall Water Splitting