Solvothermally Controlled Synthesis of Organic–Inorganic Hybrid Nanosheets as Efficient pH‐Universal Hydrogen‐Evolution Electrocatalysts

Abstract Electrocatalysts with a high efficiency and durability for the hydrogen evolution reaction (HER) hold tremendous promise for next‐generation energy conversion. Among the state‐of‐art catalysts for HER, organic–inorganic hybrid nanosheets exhibit a great potential with the merits of high activity, good durability, and low cost. Nevertheless, there is no general method for the synthesis of binary metal phosphide hybrid nanosheet HER catalysts with a tunable morphology and composition. Herein, we report a facile approach for the synthesis of nanosheets consisting of a binary cobalt nickel phosphide hybrid with a hierarchically porous nanostructures using an oxidation– phosphorization process. The as‐optimized hybrid nanosheets annealed at 350 °C yield the highest pH‐universal activity with overpotentials of 148, 111, and 173 mV in acidic, alkaline, and neutral media, respectively. Besides the promoted mass diffusion in the hierarchically porous structure, the extraordinary performance can be also attributed to the weakened adsorption of hydrogen as a result of the tunable composition of Co and Ni, which was revealed by first‐principles calculations.