Built-in electric field activates endogenous redox couple for self-sustained Fenton-like reaction

Heterogeneous catalyst systems hold significant potential for advanced water treatment, yet achieving sustainable catalytic processes capable of continuously generating reactive species remains a substantial challenge. In this work, we develop an integrated oxidation-reduction system that synergistically couples peracetic acid (PAA) with H₂O₂ under the guidance of an interfacial built-in electric field (BEF). Through a programmable self-assembly approach, a porous nitrogen-doped carbon (NC) layer encapsulating Co/CoO heterojunction was constructed. Experimental and theoretical results confirm that strong electronic coupling between metallic Co and semiconductor CoO spontaneously generates a robust BEF. This field not only optimizes the electronic configuration to enhance PAA adsorption and activation, but also enables the selective adsorption of H₂O₂ from the mixed oxidant solution. The adsorbed H₂O₂ acts as an electron donor to sustain the Co(II)/Co(III) redox cycle, facilitating continuous reactive oxygen species (ROS) generation for approximately 120 min. The system demonstrates exceptional catalytic performance, achieving high contaminant removal rate constants (0.3 to 0.6 min^-1) with an ultralow catalyst dosage of 15 mg L^-1 and significantly improved PAA utilization efficiency. This BEF-mediated "dual-enhancement" strategy offers a sustainable and efficient route for water purification by enabling high oxidant utilization while minimizing catalyst consumption.