Constructing zinc defects in zinc oxide and interface-anchoring of tricobalt tetraoxide: Modulating d-band center for efficient peroxymonosulfate activation

Abstract

Heterojunction catalysts with defects are effective for electron transfer and peroxymonosulfate (PMS) activation. In this study, a Zn vacancy-rich ZnO/Co₃O₄ (Zn_1−xO/Co₃O₄) catalyst featuring Zn-O-Co interfacial bonds was synthesized with Zn_1−xO as a matrix. Its ability to activate PMS for the degradation of ciprofloxacin (CIP) was investigated. The Zn_1−xO/Co₃O₄ achieved nearly complete CIP degradation within 20  min under 17 W sterilamp irradiation. The normalization kinetic constant was 21.7 min⁻¹ M⁻¹, which is 7.2 times higher than that of ZnO. Experimental results and theoretical calculations demonstrated that the Zn vacancy and Co species synergistically enhanced PMS adsorption. The incorporation of Co facilitated the desorption of adsorbed species from the Zn site by lowering the d-band center and promoted electron transfer to PMS. Sterilamp irradiation facilitated the generation of active radicals. The catalyst exhibited high CIP degradation ratios in the continuous-flow experiment, with over 90 % of CIP degraded within 180 min. This study presents a novel approach to enhance the catalytic activity of ZnO for pollutants degradation.