Construction of Ni–P/TiO2 Schottky heterojunction via photo-deposition to enhance photocatalytic hydrogen evolution activity

Abstract

Photocatalytic hydrogen evolution (PHE) is sustainable and environmentally friendly. Titanium dioxide (TiO2) is commonly chosen as a photocatalyst of PHE due to its non-toxicity, robust stability, and superior photocatalytic activity. However, the efficacy of TiO2 is restricted by rapid electron–hole pair recombination, limited electron mobility, and sluggish surface reactions. To address these issues, we have synthesized a Ni–P alloy onto the surface of TiO2 (Ni–P/TiO2) using a safe and efficient photo-deposition method, thereby constructing a Schottky heterojunction photocatalyst. The construction of the heterojunction significantly reduces the recombination rates of photoinduced electron–hole pairs and enhances the charge transfer rates within the photocatalyst. Additionally, the incorporation of the Ni–P alloy increases the density of oxygen vacancies, providing abundant active sites for the reduction reaction. The metallic properties of the Ni–P alloy improve the overall light absorption capacity. As a result, Ni–P/TiO2 exhibits exceptional photocatalytic hydrogen production capability. When the mass ratio of the Ni–P alloy to TiO2 is 12 wt. %, the hydrogen evolution rate reaches its maximum value at 1654.2 μmol g−1 h−1. Furthermore, density functional theory calculations substantiate that the formation of an internal electric field between the Ni–P alloy and TiO2 facilitates electron migration and carrier separation. This investigation provides a promising strategy for constructing TiO2-based Schottky heterojunctions to improve the photocatalytic hydrogen evolution performance.