Unveiling the structure–activity relationships of tetracycline degradation by photocatalytic activation peroxymonosulfate of CuBi2O4 microspheres: DFT calculation and mechanism insight

Abstract

Achieving efficient photocatalytic activation of peroxymonosulfate (PMS) degradation of pollutants through the regulation strategy of surface microstructure in catalysts remains a challenge. Herein, CuBi₂O₄ nanorods (CBO NRs) and CuBi₂O₄ microspheres (CBO Ms) were synthesized by simply regulating the alkalinity of the reaction solvent. Under full–spectrum irradiation, CBO Ms exhibited remarkable photocatalytic performance, removing 92.48% of tetracycline (TC) within 12 min, with the reaction rate constant reaching 0.2135 min⁻¹, which is approximately 2.7 times that of CBO NRs (0.0798 min⁻¹). The exposure of oxygen vacancies on the surface of CBO Ms significantly promoted the generation and migration of photogenerated carriers internally, accelerated charge accumulation at the Cu active sites on the surface, and thereby enhanced the adsorption of CBO Ms on PMS. The charge density difference results confirmed the rapid transference of surface–enriched electrons to the PMS, facilitating further activation of PMS. Radical quenching experiment and EPR testing verified that both radical (SO₄^•−, •OH) and non–radical (¹O₂) pathways were involved in the reaction system. This study offers novel insights into the design of catalysts for the photocatalytic activation of PMS to efficiently degrade environmental pollutants.