A directional Built-in electric field mediates the electron transfer synergy mechanism of the Radical/Nonradical pathway in FeOCl-CuO

Abstract Synergistic free radical/nonradical oxidation can effectively degrade toxic organic pollutants in complex aqueous environments, but a synergistic electron transfer mechanism has not been developed. In this study, a directional built-in electric field was established in FeOCl-CuO for the first time that can synergistically transfer free radical and nonfree radical electrons. The directional built-in electric field provides electron transfer channels, CuO oxidizes peroxymonosulfate (PMS) to produce 1O2 and gains electrons, electrons are transferred to FeOCl through the directional built-in electric field, and FeOCl catalyzes PMS to produce ·OH and SO4·- and loses electrons. Thus, reactive oxygen species are rapidly produced, and toxic organic pollutants are synergistically oxidatively degraded. This directional built-in electric field-mediated radical/nonradical synergistic mechanism can achieve electron synergy and overcome the electron gain/loss limitation of radical or nonradical reactions, which results in an efficient, sustained and stable catalytic degradation of toxic organic pollutants (kinetic reaction rate constant is increased 38.3 times). Pollutants could be stably removed in pilot devices. The developed kinetic model successfully predicted the kinetic reaction rate constants under different conditions. Theoretical calculations and toxicity assessment revealed that this synergistic radical/nonradical oxidation pathway can effectively degrade bisphenol A (BPA) into less toxic or harmless small molecules and capture carbon in an alkaline environment to reduce carbon emissions. This study provides new insights into the efficient, sustained, and low-carbon treatment of toxic organic wastewater by synergistic radical/nonradical oxidation in complex aqueous environments.