Lattice Strain Engineering of Ni 2 p Enables Efficient Catalytic Hydrazine Oxidation-assisted Hydrogen Production.

Hydrazine-assisted water electrolysis provides new opportunities to enable energy-saving hydrogen production while solve the issue of hydrazine pollution. Here, we report the synthesis of compressively strained Ni 2 P as a bifunctional electrocatalyst for boosting both the anodic hydrazine oxidation reaction (HzOR) and cathodic hydrogen evolution reaction (HER). Different from a multistep synthetic method that induces lattice strains by creating core-shell structures, we develop a facile strategy to tune strains of Ni 2 P via the dual cation-codoping. The obtained Ni 2 P with a compressive strain of -3.62% exhibits significantly enhanced activity for both the HzOR and HER than counterpart with tensile strains and without strains. Consequently, the optimized Ni 2 P delivers current densities of 10 and 100 mA cm -2 at small cell voltages of 0.16 and 0.39 V for hydrazine-assisted water electrolysis, respectively. Density functional theory (DFT) calculations reveal that the compression strain promotes water dissociation and concurrently tunes the adsorption strength of hydrogen intermediates, thereby facilitating the HER process on Ni 2 P. As for the HzOR, the compression strain reduces the energy barrier of potential-determining step (PDS) for the dehydrogenation of *N 2 H 4 to *N 2 H 3 . Clearly, this work not only paves a facile pathway to synthesis lattice-strained electrocatalysts via the dual cations-codoping. This article is protected by copyright. All rights reserved.