Built-in electric field-induced oxygen vacancy engineering for simultaneous amoxicillin degradation and self-powered reaction monitoring

The built-in field induces charge redistribution and O v formation at electron-poor CoFe-LDH. • O v increases the local electron density of metal active centers, enhancing PMS adsorption and interfacial electron transfer. • Electron-rich α-FeOOH facet favors 1 O 2 generation, whereas O v on the CoFe-LDH side facilitate · O 2 - production. • Toxicological evaluation and parallel dual-electrode experiments confirmed the environmental safety in practical water remediation. Constructing heterojunctions with built-in electric fields for interfacial electron regulation and defect engineering remains a formidable challenge. Herein, an oxygen vacancy (O v )-enriched α-FeOOH/CoFe-LDH heterojunction supported on graphite felt (H-CoFe/GF) was fabricated via an in-situ growth strategy. Theoretical calculations revealed that the α-FeOOH/CoFe-LDH work-function mismatch established a built-in electric field, which drove interfacial charge redistribution and promoted O v formation on the electron-deficient CoFe-LDH side. The resulting O v shifted the d -band center upward to −0.97 eV, enhancing peroxymonosulfate (PMS) adsorption and interfacial electron transfer for simultaneous amoxicillin (AMX) degradation and self-powered monitoring of the degradation process. Reactive oxygen species identification experiments, together with EPR analysis, suggest that singlet oxygen ( 1 O 2 ) and superoxide radicals ( · O 2 - ) were the predominant reactive species in the catalytic process. Thermodynamic analysis indicates that the electron-rich α-FeOOH facet favors 1 O 2 generation with a Gibbs free-energy barrier of 1.35 eV, whereas O v on the CoFe-LDH side lowers the barrier to 0.96 eV and facilitates · O 2 - production. Degradation intermediate identification and toxicological evaluation confirmed the environmental applicability of the system. This work elucidates an integrated defect-engineering mechanism mediated by built-in-electric-field, which couples facet-dependent PMS activation with degradation-correlated self-powered reaction monitoring. Download: Download high-res image (375KB) Download: Download full-size image Scheme. Diagram of operational mechanism of real-time monitoring sensor.