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 (H 2 ) production via cost-effective water electrolysis systems. This study describes single-phase metal-rich nickel phosphide (Ni 12 P 5 )-incorporated carbon composites for a highly efficient water-splitting system. The distinct Ni 12 P 5 is anchored in nitrogen (N)- and phosphorus (P)-rich carbon matrices (Ni 12 P 5 @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 Ni 12 P 5 @N,P-C composites contribute effectively toward both high oxygen evolution and hydrogen evolution reactions. Consequently, the Ni 12 P 5 @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.