Strongly coupled interface facilitating charge separation to the improved visible light-driven hydrogen production on CdS@polydopamine/NiS photocatalyst

Abstract

High-quality interfacial coupling and chemical bonds are effectively instrumental for boosting photo-generated charge separation/transfer abilities. Herein, the features of organic compound surface modification and Schottky junction are simultaneously gathered in a CdS@pDA/NiS ternary composite via the in situ self-polymerization of dopamine hydrochloride and the hydrothermal method. The polydopamine (pDA) shell coated on the surface of CdS nanorods by Cd–O bonds not only ameliorates the absorption capacity of visible light, but also heightens the charge transfer dynamics. Simultaneously, the Schottky junction makes it easier for the electrons generated by CdS to cross the Schottky barrier via the pDA electronic bridge, which promotes the vectorial migration from CdS to NiS and suppresses the electron backflow. The optimized CdS@pDA/NiS presents superior photocatalytic H₂ evolution rate up to 9.31 mmol h⁻¹ g⁻¹, which is about 11.2 and 7.69 times higher than that of pristine CdS and CdS@pDA, respectively. The apparent quantum efficiency (AQE) of the resulting material is 25.7% at a wavelength of 420 nm. In this work, reasonably designed CdS@pDA/NiS composites offer a valid case for satisfying the demand for producing clean energy.