Uncovering the neglected feedback of accumulated polyphenol toward self-enhanced electro-polymerization

Electro-polymerization has emerged as a promising wastewater treatment process due to the merits of zero CO₂ emission, little chemical/energy input, and resource recovery. However, the counterreaction of surface-adsorbed polymer toward the subsequent electro-polymerization remains indeterminate. Herein, we tried to explore the neglected feedback of surface-adsorbed polymer toward electro-polymerization. We demonstrated that the generated polyphenol gradually accumulated onto the MoO₂-based electroactive membrane, which in situ established an interfacial hydrophobicity microenvironment. This drove the formation of Mo(Ⅵ), with its steady-state concentration elevated by two orders of magnitude, and in turn promoted the phenoxy radical generation, finally triggering an unexpected self-enhanced electro-polymerization. Consequently, an over 100% electronic utilization efficiency, which was almost unrealizable in the conventional electro-oxidation system, was obtained. In addition, the surface-covered polyphenol could be recovered by a facile polarity reversal method, maximizing net profit of 53.9 ¥·m^-3. These findings shed light on the underlying potential interaction between the surface-covered polymer and the electrode.