Cu-doped CoWO4/WO3 heterojunctions as peroxymonosulfate activators for rapid degradation of organic pollutants

Abstract

Bimetallic catalysts have shown promising effects in peroxymonosulfate (PMS) activation for contaminant remediation, while the synergistic mechanism between bimetallic catalysts and photogenerated electrons remains limited. Herein, a Cu-doped CoWO₄/WO₃ catalyst (CCW) was synthesized via an aqueous bath combined with a calcination method for degradration of organic pollutants by activated PMS. In the PMS/vis system, CCW achieved complete tetracycline (TC) degradation within 6 min, with a degradation rate of 0.6369 min⁻¹, which was 8.4, 11.1, and 19.4 times higher than those of CoWO₄/WO₃, CoWO₄, and WO₃, respectively. Radical scavenging tests, EPR analysis, and band structure characterization confirmed that CoWO₄ and WO₃ formed a type-II heterojunction, with photogenerated holes (h⁺) and electrons (e⁻) serving as the main reactive species in the photocatalytic system. The activation mechanism was attributed to the rapid redox cycling of the Co–Cu bimetal and the synergistic effect with photogenerated electrons from the type-II heterojunction. The main reaction intermediates were identified via LC-MS analysis and a possible TC degradation mechanism was examined. The research presents an approach for efficiently degrading organic pollutants via visible-light-assisted PMS activation using bimetallic catalysts.