Mechanistic insight into the self-catalyzed degradation of Cu-EDTA in photocatalytic fuel cell coupled with peroxymonosulfate

Abstract

The performance and mechanism of self-catalyzed degradation of Cu-EDTA in a peroxymonosulfate (PMS)-coupled photocatalytic fuel cell (PFC) are investigated for the first time. By choosing Ca-EDTA and Pb-EDTA as controls for the comparative experiments, it was estimated that the self-catalyzed degradation of Cu-EDTA in the PMS/PFC/sunlight system contributed 41.8 % of its total degradation and 22.6 % of the total maximum output power density. The self-catalyzed degradation of Cu-EDTA via the released Cu2+ increased the contribution of h+, 1O2, and •OH to Cu-EDTA degradation. In solution, Cu2+ could activate PMS via the Cu2+/Cu+ redox cycle. Moreover, partial Cu2+ could be reduced by e− and deposited on photoanode as copper oxides/copper to form a new heterojunction with TiO2-nanotube-arrays, which improved the separation of charge-carriers and redox capacity of the photoanode, thus enhancing the photocatalysis of PFC and photocatalytic activation of PMS. Besides, the self-catalyzed degradation of Cu-EDTA increased the electricity power generation in the PFC by improving the reactivity of the photoanode and reducing the resistance via deposition. This study proposed new insights into the self-catalyzed degradation of metal-complexes in sulfate radical advanced oxidation processes and provided a clean, efficient, and economical way for Cu-EDTA degradation by enhancing this self-catalysis via the PFC.