Type-I heterojunction ZnSnO3@PDA/Na0.5Bi0.5TiO3 with PDA as interfacial electron transport bridge for efficient degradation of oxytetracycline and Acid chrome blue K

In this research, a ZnSnO₃@PDA/Na_0.5Bi_0.5TiO₃ heterojunction was constructed by coating ZnSnO₃ with PDA layer and further compounding Na_0.5Bi_0.5TiO₃ with ZnSnO₃@PDA through ultrasonic method, in which the PDA shell acted as interfacial electron transport bridge. The formation of this hybrid photocatalyst resulted in more efficient light utilization, raised charge conductivity and decreased band gap width. The adsorption and photocatalytic efficiency of ZnSnO₃@PDA/Na_0.5Bi_0.5TiO₃ for oxytetracycline and Acid chrome blue K removal were assessed. Compared with ZnSnO₃, ZnSnO₃@PDA and Na_0.5Bi_0.5TiO₃, the ZnSnO₃@PDA/Na_0.5Bi_0.5TiO₃ manifested prominent improved adsorption and photocatalytic performance, which can eliminate 100 % oxytetracycline and Acid chrome blue K within 180 and 75 min, respectively. After five-run repeated experiments, the ZnSnO₃@PDA/Na_0.5Bi_0.5TiO₃ shows 87.9 % and 94.9 % degradation rate for oxytetracycline and Acid chrome blue K, respectively, demonstrating its sufficient stability. The boosted photocatalytic performance and reusability of ZnSnO₃@PDA/Na_0.5Bi_0.5TiO₃ are attributed to the distinctive Type I heterojunction between ZnSnO₃ and Na_0.5Bi_0.5TiO₃ as well as the PDA as interfacial electron transport bridge. The experiments on radical scavenging verified that the •O₂⁻ and h⁺ oxidants are largely responsible for the photocatalytic reactions. This type I ZnSnO₃@PDA/Na_0.5Bi_0.5TiO₃ heterojunction using PDA as electron transport layer may deliver a new reference for designing and fabricating efficient heterostructural photocatalysts in the environmental purification territories.