Metal organic frameworks derived Fe-CoF₂/MXene composites as efficient Electrocatalysts for the overall water...

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). This breakthrough achievement lies in the construction of a rapid mass transfer structure: porous cubes increase the contact area of reactants and create convection channels to achieve rapid bubble separation. The synergistic effect of Fe-doped CoF₂ and MXene not only optimizes the adsorption of intermediates but also promotes rapid electron transfer at the interface, and robust structural robustness. Remarkably, the optimized catalyst achieves low overpotentials of 121 mV (hydrogen evolution reaction, HER) and 210 mV (oxygen evolution reaction, OER) at 10 mA cm^-2, 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-h 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.