Dual-strategy modification of NiMoO4 yields high performance bifunctional water splitting catalysts

Nickel molybdate has become a potential replacement for precious metal catalysts in water splitting due to its ease of adjusting microstructure and electronic structure. However, its inherent low catalytic activity limits the OER and HER performance and stability of the catalyst. This work employs a simple one step hydrothermal method to synthesize iron-doped nickel molybdate (FNMO) on a self-assembled Ti3C2/NF substrate, followed by phosphorating treatment with PH3 gas to obtain the phosphorated product Pi/FNMO/Ti3C2/NF nanorod array catalyst. The Pi/FNMO/Ti3C2/NF catalyst exhibits superior oxygen evolution reaction (OER) activity (116.8 mV @ 10 mA cm−2) and hydrogen evolution reaction (HER) activity (73 mV @ 10 mA cm−2), significantly surpassing commercial Pt/C and RuO2 catalysts. This may be attributed to the formation of a heterojunction between FNMO and Ti3C2 within the Pi/FNMO/Ti3C2/NF composite following phosphorylation, which modulates the electronic structure and reduces the overpotentials for both the OER and HER. Meantime, Pi/FNMO/Ti3C2/NF as a dual-function catalyst only needs 1.57 V to drive overall water splitting at a current density of 100 mA cm−2 and maintain stable output for 180 h with a decay rate of only 0.55%. This work demonstrates the feasibility of enhancing overall water splitting performance through the incorporation of heteroatom doping and phosphorylation modification in nickel molybdate-MXene composites, laying the foundation for their widespread commercial application.