Investigation of the photoelectric properties of nanostructured CeO/CuO heterojunction: Photocatalytic degradation of sulfadiazine in water.

The rapid complexation of photogenerated electrons-holes with copper (Cu) greatly limits the large-scale application of cuprous oxide (CuO) as a photocatalyst. Therefore, using a hydrothermal method, a type Ⅱ heterojunction structure was constructed by modifying CuO with cerium (IV) oxide (CeO). The CeO/CuO heterojunction photocatalyst effectively increased the photogenerated electron density and reduced the surface transfer impedance. The improved separation of photogenerated electron-hole pairs resulted in excellent photocatalytic activity. Consequently, the sulfadiazine (SDZ) degradation rate by CeO/CuO reached 87.5%. Furthermore, after five cycles, the SDZ degradation rate remained as high as 78.5%, demonstrating the good stability of CeO/CuO. The SDZ degradation intermediates were analyzed using high-performance liquid chromatography-tandem mass spectrometry, and possible degradation pathways were proposed. Trapping agent experiments, and energy band structure calculations revealed that CeO/CuO photocatalyzes SDZ degradation via a type Ⅱ heterojunction charge transfer mechanism. Finally, the total organic carbon showed that SDZ eventually decomposed to CO and HO, with complete SDZ degradation. This study provides a reference for the preparation of visible light-responsive photocatalysts.