Interfacial oxygen vacancy engineering and built-in electric field mediated Z-scheme In2O3/Ag3PO4 heterojunction for boosted photocatalytic doxycycline degradation

Doxycycline pollutants in environment seriously destroy the balance of ecological system. A Z-scheme In2O3/Ag3PO4 heterojunction is constructed by attaching Ag3PO4 nanoparticles on hollow In2O3 hexagonal prism structures for efficient degradation of doxycycline. The doxycycline (30 mg/L) removal rate by IAO-1 (mole ratio of In2O3:Ag3PO4 is 1:3, 1.0 g/L) reaches 99.7 % under visible light irradiation. Degradation rates are almost unchanged after five cycles of degradation experiments, demonstrating the excellent reusability and stability of the IAO-1 photocatalyst. The photocatalytic degradation of doxycycline in different water matrices by IAO-1 shows excellent performance, which provides significant potential for practical applications. The experiments and DFT results demonstrate that the built-in electric fields in IAO-1 contribute to the charge transfer from Ag3PO4 to In2O3, leading to the formation of a Z-scheme heterojunction with high redox capacity. The hollow defect structure of IAO-1 effectively activates molecular oxygen to generate oxygen vacancies and induce 1O2 production through energy transfer, which promotes the attack of benzene rings and oxygen-containing groups in the molecular structure of doxycycline, leading to hydroxylation, demethylation, and ring-opening reactions. This work provides new ideas for constructing Z-scheme photocatalysts with oxygen vacancies and built-in electric fields for practical wastewater treatment.