Noble-metal-free nickel phosphide modified CdS/C3N4 nanorods for dramatically enhanced photocatalytic hydrogen evolution under visible light irradiation

Abstract

Photocatalytic hydrogen evolution is a promising technology in solving the global energy and environment issues. Therefore, it is urgent to develop highly efficient, nonprecious metal and stable photocatalysts. In this work, we synthesized a highly efficient Ni₂P–CdS/g-C₃N₄ composite based on the concept of combining heterojunction engineering with co-catalyst modification. When employed as a photocatalyst for water splitting, the obtained best composite (5% Ni₂P–CdS/g-C₃N₄) displayed dramatically enhanced hydrogen evolution activity at the rate of 44 450 μmol h⁻¹ g⁻¹, which was about 27 times higher than that of pure CdS (1668 μmol h⁻¹ g⁻¹). The apparent quantum yield at 420 nm reaches 46.3%. The excellent photocatalytic activity and stability can be ascribed to the synergistic effect of the intimate contact between CdS and g-C₃N₄ and the surface co-catalyst modification. Specifically, the g-C₃N₄ coated on the CdS nanorods can effectively promote the electron−hole pair separation spatially and Ni₂P can lower the overpotential of H⁺ reduction.