Interfacial Electric Field Tuning Carbon-Catalyzed Persulfate Activation toward a Maneuverable Oxidation Pathway for Enhanced Removal of Bisphenol A

Carbocatalyst/persulfate is a green, highly oxidative system for decontaminating refractory aqueous organic pollutants. Exploring facile routes to tune the catalytic activity and selectivity (persulfate activation pathway) of carbonaceous materials toward persulfate activation is very appealing, which offers a platform for selective oxidation of organic pollutants. In this work, we showed that the interfacial electric field (IEF) is a facile approach to alter the catalytic activity and selectivity of carbon/persulfate systems via the field-dipole effect. To study the IEF effects, a carbon electrode fabricated from powdery carbons was assembled into an asymmetric quasi-capacitive deionization cell, and positive/negative voltages were applied. Through integrated experimental and theoretical investigations, we found that the bond structures of both persulfate anion and its transition state were changed under IEF, while the scenarios in the cases of positive and negative IEF were distinct. Positive IEF induces/reinforces the nonradical oxidation pathway based on carbon-persulfate complexes in the carbon/persulfate system, while different persulfate activation pathways (nonradical carbon-persulfate complexes and/or free radicals) can be induced under negative IEF depending on the bonding strength between persulfate and the carbocatalyst. Our results offer a feasible approach to tune the redox potentials of carbon-based advanced oxidation systems toward selective oxidation of organic pollutants.