Synergistic Activation of Crystalline Ni2P and Amorphous NiMoOx for Efficient Water Splitting at High Current Densities

The overpotential of alkaline water electrolysis at high current density is significantly increased by the high energy barriers of high intermediate (H* and OH*) and slow mass/charge transfer. Modifying the electronic structure and morphology of catalysts to decrease energy barriers and enhance mass/charge transfer is a promising approach, but it presents significant challenges. In this study, the crystalline Ni2P clusters were coupled with an amorphous NiMoOx nanorod support on a nickel foam substrate (Ni2P–NiMoOx/NF) to create a heterojunction that enhances mass/charge transfer, tunes energy barriers, and improves reaction kinetics through synergistic activation. The Ni2P–NiMoOx/NF exhibits ultralow overpotentials of 91, 188, and 297 mV at 10, 100, and 500 mA cm–2, respectively, for the hydrogen evolution reaction, along with stability. It also shows superior performance in the oxygen evolution reaction. Remarkably, the Ni2P–NiMoOx/NF-based electrolyzer achieves 100 and 400 mA cm–2 at low cell voltages of 1.66 and 2.08 V, respectively, while also maintaining stable electrolysis for 100 h under industrial testing (65 °C with 30% KOH). Additional characterization and density functional theory calculations demonstrate that the interaction between Ni2P and NiMoOx facilitates the downshifting of d-band centers to the Fermi level, which results in the activation of the local electronic structure, promoting H2O dissociation and enhancing the overall catalytic activity.