Synthesis of the g-C₃N₄/CdS Nanocomposite with a Chemically Bonded Interface for Enhanced Sunlight-Driven CO₂ Photoreduction

The work, herein, reports a simple approach for the synthesis of the g-C3N4/CdS nanocomposite. The high pressure NH3 and H2S, which is created by the polycondensation of thiourea, processes simultaneously the gas-induced lysis to fracture the carbon nitride framework, and the sulfidation of adsorbed Cd precursor to form CdS nanoparticles (NPs) with high crystallinity on the surface of the modified carbon nitride structure. These processes synchronously alter the fragmentation mechanism of the carbon nitride framework and shift the crystal grow orientation of the CdS NPs. Importantly, they result in the creation of the C–S–Cd bridges that induce an intimate chemically bonded interface between g-C3N4 and CdS NPs. The heterostructure coupled with this chemically bonded interface favors effective charge separation and transfer. The as-prepared nanocomposite photocatalyst exhibits an efficient sunlight-driven photoreduction of CO2 into CO, which are superior to those of the g-C3N4 material and CdS NPs alone, in the presence of the metal–organic complex as a co-catalyst. CO selectivity is greatly enhanced, as compared to the g-C3N4 material, indicating the critical role of CdS NPs in the composite to promote the interaction with the co-catalyst, thus enhancing the CO2 reduction and decreasing the side reaction of the H2 evolution.