In Situ Synthesis of Strongly Coupled Co₂P-CdS Nanohybrids: An Effective Strategy To Regulate Photocatalytic Hydrogen Evolution Activity

Noble-metal-free photocatalyst Co 2 P-CdS was synthesized via a facile in situ hydrothermal method for the first time to boost the performance of photocatalytic H 2 production. This synthesis process allows the Co 2 P nanoparticles to disperse evenly on the surface of CdS sub-microspheres and to form unique intimate contact interfaces. The physical and photophysical properties of as-prepared Co 2 P-CdS composite samples were characterized by X-ray diffractometry, transmission electron microscopy, UV–vis diffusion reflectance spectroscopy, X-ray photoelectron spectroscopy, photoluminescence, and surface photovoltage (SPV) spectroscopy. The results indicate that the photocatalytic H 2 evolution activity of CdS sub-microspheres under visible-light irradiation is significantly enhanced by introducing inexpensive Co 2 P as co-catalyst. The Co 2 P-CdS sample with a loading of 1.2 mol% Co 2 P gives the highest H 2 production rate of 0.303 mmol·h –1, which was about 3 times higher than that achieved with 0.5 wt% Pt-loaded CdS sample. After further introduction of K 2 HPO 4 as sacrificial agent, the H 2 production rate reached 0.356 mmol·h –1, which is 41 times higher than that obtained with pure CdS. The apparent quantum yield of the Co 2 P-decorated CdS sample is about 13.88% at 420 nm. These results suggest that the synergistic effect between Co 2 P and CdS greatly enhances the photocatalytic activity of CdS. Moreover, a reasonable mechanism for the enhanced photocatalytic activity was proposed through density functional theory calculation and verified by SPV spectroscopy.