Bi2O2CO3/Bi2O3 Z-scheme photocatalyst with oxygen vacancies and Bi for enhanced visible-light photocatalytic degradation of tetracycline

Abstract

Since it has been found that tetracycline (TC) causes significant harm to ecosystems and human health, there has been an intense commitment toward its effective remediation in the ambient environment. For this study, a novel bismuth subcarbonate/bismuth oxide (Bi₂O₂CO₃/Bi₂O₃) heterojunction photocatalyst containing oxygen vacancies (OVs) and bismuth (Bi-BOC/BO-OVs) was successfully synthesized using a simple calcination method. The defect state provided by the OVs increased light absorption and the population of adsorption sites, which played pivotal roles in the removal of TC. Therefore, within the catalyst dosage range of 0.4 g L⁻¹, the reaction rate constant increased with greater TC adsorption. As a bridge for electron transport, bismuth (Bi) linked the valence band of Bi₂O₂CO₃ and the conduction band of Bi₂O₃ to form a Z-scheme heterojunction structure, which promoted the effective separation of electron–hole pairs and the yield of active oxygen species. Consequently, the Bi-BOC/BO-OVs demonstrated a significantly enhanced photocatalytic degradation capacity for TC under visible light irradiation. The sufficient degradation of TC in simulated water matrices and different initial pH indicated that the Bi-BOC/BO-OV photocatalytic system possessed tremendous potential for the remediation of TC wastewater.