A Janus Nickel Cobalt Phosphide Catalyst for High-Efficiency Neutral-pH Water Splitting

Transition-metal phosphides have stimulated great interest as catalysts to drive the hydrogen evolution reaction (HER), but their use as bifunctional catalytic electrodes that enable efficient neutral-pH water splitting has rarely been achieved. Herein, we report the synthesis of ternary Ni_0.1Co_0.9P porous nanosheets onto conductive carbon fiber paper that can efficiently and robustly catalyze both the HER and water oxidation in 1 m phosphate buffer (PBS; pH 7) electrolyte under ambient conditions. A water electrolysis cell comprising the Ni_0.1Co_0.9P electrodes demonstrates remarkable activity and stability for the electrochemical splitting of neutral-pH water. We attribute this performance to the new ternary Ni_0.1Co_0.9P structure with porous surfaces and favorable electronic states resulting from the synergistic interplay between nickel and cobalt. Ternary metal phosphides hold promise as efficient and low-cost catalysts for neutral-pH water splitting devices.