Leveraging Polaron Effect for Solar-Driven Efficient Peroxymonosulfate Activation in Water Purification

Peroxymonosulfate (PMS) represents a promising advanced oxidation technique for the treatment of refractory pollutants; however, its application is limited by high costs resulting from excessive usage due to low activation efficiency. In this study, we formulated a sunlight-driven Cu₁-O_v/TiO₂ catalyst with surface electron polaron sites to activate PMS for the degradation of contaminants, achieving a record reaction rate of k = 2.998 min^-1 even with a low PMS dosage of 0.3 mM. The adsorption process and electron transfer kinetics were significantly enhanced with surface polaron sites in Cu₁-O_v/TiO₂, which facilitated the activation of PMS and increased the reaction rate constant k by 29.1 times compared with that of TiO₂/PMS under illumination. Additionally, we verified that light irradiation promotes transfer from the non-free-radical pathway to the efficient free-radical pathway in mechanism of PMS activation. Our designed sunlight-driven flow-through PMS setup achieves a removal rate exceeding 90% for 7 days of outdoor operation at 3.2 × 10² L m^-2 h^-1, the feasibility of which is further proven in regions around the world by analysis of solar intensity. This study presents a demonstration of economical PMS application in water purification worldwide, with an estimated cost of 0.135 $ m^-3.