Anchoring of Ni₁₂P₅ Microbricks in Nitrogen- and Phosphorus-Enriched Carbon Frameworks: Engineering Bifunctional Active Sites for Efficient Water-Splitting Systems

The demand for developing high-efficiency multifunctional electrocatalysts with a long-term stability rapidly increases for achieving the commercialization of sustainable hydrogen (H₂) production via cost-effective water electrolysis systems. This study describes single-phase metal-rich nickel phosphide (Ni₁₂P₅)-incorporated carbon composites for a highly efficient water-splitting system. The distinct Ni₁₂P₅ is anchored in nitrogen (N)- and phosphorus (P)-rich carbon matrices (Ni₁₂P₅@N,P-C); the creation of the matrices entails a facile hydrothermal-followed pyrolysis treatment to explore their bifunctional activities in the water-splitting system. Owing to the superior activity of the rich Ni (δ⁺) component for the production of molecular oxygen and that of P (δ⁻)­and N species in the carbon framework for hydrogen adsorption, the optimized Ni₁₂P₅@N,P-C composites contribute effectively toward both high oxygen evolution and hydrogen evolution reactions. Consequently, the Ni₁₂P₅@N,P-C composite-based two-electrode water-splitting system shows a low operating potential of 1.57 V at 10 mA cm^–2 and achieves the commercially required high current density of 500 mA cm^–2 at a stable potential of 2 V. The functionalization of composite electrocatalysts based on strategical engineering and the intrusion of multiple active sites can help develop enhanced electrochemical energy systems.