In situ construction of a flower-like Z-scheme Co3O4/CoO heterostructure with superior photoelectrocatalytic performance

Photoelectric catalytic oxidation (PEC) is a promising strategy to degrade antibiotic refractory pollutants into CO2 and H2O. A flower-like Co3O4/CoO catalyst with tight interfacial contact was constructed by the in-situ reduction of a part of CoO from the flower-like Co3O4 surface. The Co3O4/CoO heterostructure was fully characterized, and its PEC performance was investigated. The removal rate of tetracycline (TC) by Co3O4/CoO was 98.2% within 150 min, which was nearly 1.5 and 2.0 times those of Co3O4 and CoO, respectively. The significant improvement of Co3O4/CoO was attributed to the establishment of the built-in electric field on the heterojunction contact interface, which accelerated the charge transfer in the interface. Meanwhile, the significant synergistic effect between the electrocatalytic and photocatalytic processes in PEC, with a synergistic factor reaching 3.7, realized the spatial separation of charge carriers and generated more active species that participate in TC degradation. Density functional theory (DFT) calculations and electron paramagnetic resonance (ESR) results proved that the charge transfer mechanism followed the Z-scheme heterojunction structure. Furthermore, two possible degradation pathways of TC were proposed by liquid chromatography-mass spectrometry. This work provided a promising catalyst for removing antibiotic pollutants.