Study on the controlled preparation of ZnO/CdS and its photocatalytic performance enhanced by Au particles

Presently, the issue of water pollution is escalating, underscoring the paramount importance of research into catalyzing the degradation of water using renewable energy sources, such as solar energy. This study employs hydrothermal, chemical bath deposition, and atomic layer deposition (ALD) techniques to fabricate a sea urchin-shaped ZnO/CdS/Au ternary composite photocatalyst deposited on zinc foil. The collaborative effect of ZnO-absorbing ultraviolet light and CdS-absorbing visible light achieves a broad-spectrum response to ultraviolet-visible light. Au particles, acting as carrier bridges, facilitate the migration of charge carriers, thereby augmenting the photocatalytic performance. The material underwent comprehensive characterization of its surface morphology, phase structure, and optical properties employing scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), transmission electron microscopy (TEM), X-ray diffractometer (XRD), and ultraviolet-visible spectrophotometer (UV-Vis). The impact of hydrothermal time, temperature, and reaction system concentration on the microstructure and morphology is scrutinized. Experimental results show that ZnO/CdS/Au has a unique skeleton structure, which can provide more active sites and exhibit better photocatalytic activity. UV results indicate an intensified visible light absorption and a narrowed bandgap, resulting in enhanced photocatalytic performance. Photocatalytic applications demonstrate that within 60 min, the degradation rate of MB reaches 94.4%. This represents a 2.6-fold increase in degradation speed compared to pure ZnO and a 1.8-fold increase compared to the binary composite ZnO/CdS. In comparison to other catalysts, ZnO/CdS/Au possesses advantages, such as low cost, excellent stability, non-toxicity, and environmental friendliness. It emerges as a promising photocatalyst for the degradation of organic pollutants in wastewater treatment.