Unveiling a MnxCo1−xSe Fenton-like catalyst for organic pollutant degradation: A key role of ternary redox cycle and Se vacancy

Abstract

In this study, the MnxCo1−xSe catalysts were synthesized and employed in Fenton-like reactions for the degradation of organic pollutants. The Mn0.5Co0.5Se composite with 1:1 dosing ratio (Mn:Co) represented the best catalytic performance and showed higher reusability and stability in five cycles. The optimum conditions for target pollutant removal were 0.1 g/L catalyst dosage, 2.6 mM H2O2 concentration, and initial pH 7.0 according to the result of a response surface approach. The high catalytic efficiency of the MnxCo1−xSe catalyst was attributed to the high-performance cycle of Mn/Co/Se elements between their oxidic and reduced states. Both non-radical processes (based on 1O2) and radical processes (based on •OH and •O2–) were verified to be involved in the degradation of Acid Orange 7 (AO7). Se vacancy on the MnxCo1−xSe surfaces was identified and it played a significant way in the generation of non-radical 1O2. The AO7 degradation intermediates and toxicity analysis were also evaluated. This study provides new insights on the Se-based bimetal redox cycle in the Fenton-like process, promoting its application in organic pollutants degradation.