Construction of Ni@Ni ₂P Cocatalyst with Core-Shell Nanostructure for High-Efficiency Photocatalytic Hydrogen Production Over G-C ₃N ₄

Abstract

Construction of a high-efficiency and low-cost core-shell cocatalyst on g-C₃N₄ is of great significance for realizing efficient photocatalytic hydrogen production. However, developing a synthetic method for directly preparing core-shell nanocrystals with well-defined structure is still a great challenge. Herein, Ni@Ni₂P cocatalyst with core-shell structure was rationally fabricated on the surface of g-C₃N₄ by solvothermal reduction and solid-state phosphorization reaction, of which the amount can strongly influence the photocatalytic hydrogen production performance. The optimal photocatalytic hydrogen production rate of 50P-Ni reaches 2935 μmol h^-1 g^-1 with no obvious decline in performance over 3 h testing under light irradiation, which is about 3.5-fold and 137-fold higher than that of Ni/g-C₃N₄ and g-C₃N₄. The systematic investigations reveal that Ni@Ni₂P core-shell cocatalyst not only makes the metal nickel stability from corrosion, but also prolongs the recombination time of photogenerated electrons and holes that results in a better separation efficiency, confirmed by the surface photovoltage, transient photovoltage and photoluminescence. This work provides a useful inspiration on consciously designing of a robust and efficient cocatalyst with core-shell structure for photocatalytic H² evolution from water splitting.

Keywords: g-C3N4, Ni@Ni2P cocatalyst, core-shell nanostructure, H2 evolution, charge transfer