The tuned Schottky barrier of a CoP co-catalyst via the bridge of ohmic contact from molybdenum metal for enhanced photocatalytic hydrogen evolution

Abstract

The tuning of the Mott–Schottky barrier for obtaining superior separation and transfer efficiency of photogenerated carriers is significant for metallic co-catalyst-modified photocatalytic materials. Metallic cobalt phosphide (CoP) has been regarded as a promising co-catalyst for replacing Pt in the photocatalytic hydrogen evolution reaction (HER). However, it is still challenging to enhance the kinetics of CoP for the HER while lowering the Schottky barrier and improving electron transport properties. Herein, Mo metal was introduced into CoP and graphite carbon nitride (g-C₃N₄) as a bridge of electron transfer channels for synchronous tuning of the Schottky barrier. The analyses showed that the original Schottky contact between CoP and g-C₃N₄ was transformed into an ohmic contact by the introduction of metallic Mo, which caused a decrease in the Schottky barrier and even improved the charge transfer, lowered the HER potential, and accelerated the HER kinetics process of CoP. After rational assembly, the optimum photocatalyst (Mo-CoP@CN-1.0) showed a remarkable photocatalytic HER rate of 1.47 mmol g⁻¹ h⁻¹ under visible light irradiation, which was about twice as high as that of the optimal Pt modified g-C₃N₄. This study provides a new prospect for the rational design of a high-efficiency co-catalyst and provides a new way for regulating the Mott–Schottky barrier.