Lewis acid sites-regulated microscopic interface on graphite felt surface for enhanced heterogeneous electro-Fenton...

The short lifetime and limited diffusion capability of hydroxyl radicals (•OH) restrict the further development of heterogeneous electro-Fenton (Hetero-EF) technology. In contrast, singlet oxygen (¹O₂) demonstrates many advantages over •OH. In the present work, a porous confined graphite felt (PCGF) was prepared through in-situ etching of nickel oxide (NiO_x) and used as the cathode for Hetero-EF, aiming at constructing a ¹O₂-dominated Hetero-EF system to enhance its degradation performance for various antibiotic pollutants in wastewater. The in-situ etching of NiO_x introduced abundant Lewis acid sites within the porous architecture of PCGF, enabling the modulation of electrode's interfacial properties and selective adsorption of Lewis basic substances, thereby generating a characteristic "confinement effect". This enhanced interfacial interaction achieved 50.23 % adsorptive removal of oxytetracycline within 30 min without external power supply, facilitating the enrichment of pollutants at the cathode interface. Meanwhile, the "confinement effect" significantly enhanced the utilization efficiency of reactive oxygen species and the selectivity of ¹O₂. The PCGF electrode demonstrated excellent degradation performance across a wide range of pH and exhibited strong anti-interference capability. The results from radical quenching experiments and density functional theory calculations revealed that the generation of ¹O₂ proceeded through multiple routes involving hydrogen peroxide, •OH, and superoxide anions. The present study presents a novel strategy for advancing the development of ¹O₂-dominated Hetero-EF systems for treating antibiotic-containing wastewaters.