Photoelectrocatalytic peroxymonosulfate activation over CoFeO-BiVO photoanode for environmental purification: Unveiling of multi-active sites, interfacial engineering and degradation pathways.

This work reported on the development of CoFeO-BiVO photoanode based photoelectrocatalytic system collaborating with peroxymonosulfate activation for organic contaminants removal. CoFeO layer not only provided active sites for direct peroxymonosulfate activation but also accelerated charge separation process for the enhancement of photocurrent density and photoelectrocatalytic performance. Junction of CoFeO layer on BiVO photoanode led to the improvement of photocurrent density to 4.43 mA/cm at 1.23 V, which was approximately 4.06 times higher than that of pure BiVO. Subsequently, the corresponding optimal degradation efficiency toward the tetracycline model contaminant achieved to be 89.1% with total organic carbon removal value of about 43.7% within 60 min. Moreover, the degradation rate constant of CoFeO-BiVO photoanode in photoelectrocatalytic system was 0.037 min, which was about 1.23, 2.64 and 3.70 times higher than the values in photocatalysis, electrocatalysis and PMS only based systems, respectively. In addition, radical scavenging experiments and electron spin resonance spectra indicated a synergy of radical and nonradical coupling process where •OH and O played vital roles during tetracycline degradation. Plausible photoelectrocatalytic mechanism and degradation pathway were proposed. This work provided an effective strategy to construct peroxymonosulfate assisted photoelectrocatalytic system toward green environmental applications.