Construction and photodegradation performance of CdS-Sn3O4 heterojunction

Abstract

A uniformly distributed photocatalytic composite material CdS-Sn₃O₄ heterojunction was constructed. Mixed valence tin oxide Sn₃O₄ was selected as a co-catalyst to improve the stability and photocatalytic activity of the composite because Sn₃O₄ possesses adjustable band gap and matches well with the CdS band position. The characterizations of EDS and XPS proved that Sn₃O₄ was successfully loaded on CdS. The composite material exhibits an excellent band gap of 2.25 eV, a high photo-generated current intensity and good photoluminescence properties. Due to the timely transfer of photo-generated electrons from CdS material to Sn₃O₄, the recombination of electron and hole is reduced, resulting in significant increase of photocurrent density and photocatalytic efficiency. The photocatalytic degradation experiments show that CdS-Sn₃O₄ possesses a significant degradation effect on antibiotics norfloxacin and tetracycline. Simultaneously, it also exhibits certain degradation effects on organic dye pollutants methylene blue and Rhodamine B. The active substances analysis shows that H₂O₂ and hole (h⁺) are the main active substances. Composite CdS-Sn₃O₄ still maintains a stable structure and good photocatalytic activity after several photocatalysis cycles. In brief, this heterojunction material is promising in water treatment and environmental protection.