Noble metal-free bimetallic phosphide-decorated Zn0.5Cd0.5S with efficient photocatalytic H2 evolution†

Abstract

The rapid recombination of charge carriers in semiconductor-based photocatalysts results in a low photocatalytic activity. Co-catalysis is considered a promising strategy to improve the photocatalytic performance of semiconductors. In this study, a bimetallic phosphide was grown by a facile in situ growth method. Loading the cocatalyst (7 wt% NiCoP) leads to activity enhancement by a factor of approximately 27 times in the visible-light-driven hydrogen evolution relative to the pristine Zn_0.5Cd_0.5S. The photocatalysis shows a high hydrogen evolution rate of 19.5 mmol g⁻¹ h⁻¹, which is much higher than that of the single metal phosphide (Ni₂P: 7.0 mmol g⁻¹ h⁻¹; Co_xP: 8.1 mmol g⁻¹ h⁻¹) and 7 wt% Pt modified Zn_0.5Cd_0.5S (0.3 mmol g⁻¹ h⁻¹). Its apparent quantum efficiency reaches 41.6% at 420 nm. Moreover, the photocatalyst exhibits a remarkable photostability for five consecutive cycles of photocatalytic activity measurements with a total reaction time of 15 hours. The excellent photocatalytic activity of the photocatalyst was attributed to the in situ-formed NiCoP cocatalyst, which not only acts as a reactive site but also accelerates the separation of charge carriers.