Mxene-supported cobalt-molybdenum bimetallic phosphide constructs heterojunctions to regulate the electronic structure for efficient alkaline water splitting

Transition metal phosphides have garnered substantial attention as highly promising catalysts for alkaline water electrolysis. However, the agglomeration tendency of transition metal phosphides and their limited electronic tunability have restricted their further development as bifunctional water electrolysis catalysts. This study proposes a simple and efficient strategy of strong electrostatic adsorption-electrodeposition to prepare a CoMo-P@MXene/NF bifunctional catalyst with a rough surface structure on foam nickel. Ti₃C₂T_x MXene, with its excellent surface physicochemical properties, not only inhibits the agglomeration of transition metal phosphides but also enhances the conductivity and hydrophilicity of the catalyst, accelerating the penetration of the electrolyte. Moreover, DFT calculations and experimental validation indicate that the heterojunction formed by coupling cobalt-molybdenum transition bimetallic phosphides with Ti₃C₂T_x MXene modifies the electronic configuration of the active sites. This not only decreases the dissociation energy barrier of water molecules but also optimizes the adsorption/desorption free energy of intermediates in water electrolysis reactions on the catalyst surface, thus expediting the catalytic reaction kinetics of the HER and OER. In 1 M KOH solution, the CoMo-P@MXene/NF catalyst, functioning as a bifunctional catalyst, necessitates overpotentials of merely 35.2 mV and 193 mV for HER and OER, respectively, to attain a current density of 10 mA cm⁻². Furthermore, an alkaline electrolyzer constituted by CoMo-P@MXene/NF requires only a full water-splitting voltage of 1.46 V to reach a current density of 10 mA cm⁻². This study provides a reference for the preparation of transition metal phosphide/two-dimensional MXene heterostructure catalysts.