Z-Scheme Zinc oxide–Cadmium sulfide Tribocatalyst for Efficient Degradation of Tetracycline Hydrochloride

The use and discharge of antibiotics have posed a significant threat to aquatic ecosystems. Tetracycline antibiotics such as tetracycline hydrochloride (TCH) are of particular concern owing to their environmental persistence and ecological toxicity. Herein, we report the synthesis of a Z-scheme heterojunction zinc oxide (ZnO)–cadmium sulfide (CdS) composite via chemical bath deposition, which was used for the tribocatalytic degradation of TCH. Experimental results demonstrated that under optimal conditions (100-mg catalyst, 50-mL TCH solution, and 300 rpm), the optimized sample (ZC30)exhibited 97% efficiency for TCH degradation within 20 min and >98% efficiency after 100 min, with a high total organic carbon removal rate of 81.02%, demonstrating excellent mineralization capability. The formation of the ZnO–CdS heterojunction and its Z-scheme electron transfer mechanism were confirmed via multiple characterization techniques: X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy. Scavenging experiments and electron spin resonance analysis revealed that superoxide radicals (·O 2 − ) were the dominant reactive species in the degradation process. The catalyst retained a high degradation efficiency and structural stability for over five consecutive cycles, indicating a strong potential for practical applications. Download: Download high-res image (190KB) Download: Download full-size image