Inner‐Axial Chlorine Engineering Enables Efficient and Selective Phenol Electrocatalytic Upcycling to Benzoquinone on Noble‐Metal‐Free Catalysts

Abstract

Abstract Electrocatalytic upcycling of aqueous phenol into value‐added para ‐benzoquinone ( p ‐BQ) provides a promising route for synergistic wastewater treatment and sustainable chemical synthesis. Nevertheless, previous attempts have primarily relied on noble metal‐based (e.g., Pd, Ru) electrocatalysts, but struggled with high costs and low selectivity. We, herein, report a noble‐metal‐free catalyst comprising carbon nanotube (CNT)‐supported CoN 4 sites coordinated with inner‐axial chloride atoms (Co‐CNT‐Cl), delivering 92.4% phenol conversion and 83.7% p ‐BQ yield under mild conditions. The superior electrocatalytic performance stems from inner‐axial coordination of Cl, which fine‐tunes the CoN 4 site microenvironment and electronic structure. This modification enhances charge‐transfer capacity, optimizes oxidation thermodynamics, and facilitates phenol adsorption and p ‐BQ desorption. The proposed electrocatalytic system with the Co‐CNT‐Cl catalyst, maintains > 80.3% phenol conversion and > 70.7% p ‐BQ yield over 10 consecutive cycles. Furthermore, integrating the Co‐CNT‐Cl catalyst into a continuous‐flow electrolyzer enables efficiently operational stability. This work establishes a potential and cost‐effective electrocatalytic approach to valorize phenolic wastewater through resource recovery.