Defect-rich cobalt pyrophosphate hybrids decorated Cd0.5Zn0.5S for efficient photocatalytic hydrogen evolution: Defect and interface engineering

Abstract

Photocatalysts with highly efficient charge separation are of critical significance for improving photocatalytic hydrogen production performance. Herein, a cost-effective and high-performance composite photocatalyst, cobalt-phosphonate-derived defect-rich cobalt pyrophosphate hybrids (CoPPi-M) modified Cd_0.5Zn_0.5S is rationally devised via defect and interface engineering, in which the co-catalyst CoPPi-M delivers a strong interaction with host photocatalyst Cd_0.5Zn_0.5S, rendering Cd_0.5Zn_0.5S/CoPPi-M with a remarkably improved efficiency of charge separation and migration. Besides, Cd_0.5Zn_0.5S/CoPPi-M exhibits a hydrophilic surface with ample access to electrons and a strong reduction ability of electrons. Benefiting from these advantages, the integration of defect-rich cobalt pyrophosphate and Cd_0.5Zn_0.5S enables Cd_0.5Zn_0.5S/CoPPi-M-5% with high photocatalytic H₂ production rate of 6.87 mmol g^-1h^-1, which is 2.46 times higher than that of pristine Cd_0.5Zn_0.5S, and the notable apparent quantum efficiency (AQE) is 20.7% at 420 nm. This work provides a promising route for promoting the photocatalytic performance of non-precious hybrid photocatalyst via defect and interface engineering, and advances energy-generation and environment-restoration devices.

Keywords: Cd(0.5)Zn(0.5)S; Cobalt pyrophosphate; Hydrophilic co-catalyst; Interfacial engineering; Oxygen vacancies; Photocatalytic hydrogen production.