Regulating the electronic structure of N-doped carbon enabled by B doping toward enhanced •OH generation for...

Heterogeneous electro-Fenton (EF) is an attractive process for refractory and hazardous pollutants degradation that usually relies on •OH produced via the in-situ decomposition of electro-generated H₂O₂ on metal-based catalytic sites, which faces the problems of metal shedding and leaching under acidic or even neutral conditions. Designing and investigating a bifunctional metal-free catalyst is a sensible strategy for the development of heterogeneous EF process. Herein, the bifunctional metal-free boron and nitrogen co-doped porous carbon (B_XNPC) catalysts were prepared. Total organic carbon removals of hazardous and refractory antibiotics (ciprofloxacin, levofloxacin, sulfamethoxazole, tetracycline, and norfloxacin) by B₅₀NPC EF process were 67 ± 2% - 90 ± 2% in 3 h. This process could efficiently treat actual pharmaceutical factory wastewater that chemical oxygen demand (COD) removal was 86.8 ± 1.3% with specific energy consumption of 3.7 ± 0.2-6.7 ± 0.1 kWh (kg COD)^-1 superior to previous reports (5.5-290 kWh (kg COD)^-1). Theoretical calculations and experiments revealed that the B sites and carbon defects in B₅₀NPC promoted •OH and ¹O₂ generation, respectively, synergistically enhancing antibiotics removal. The results of toxicity evaluation and E. coli deactivation demonstrated excellent detoxification and disinfection performance. The results gain deep insights into the O₂ reduction mechanism of bifunctional metal-free B_XNPC and developing an energy-efficient electrochemical process for promoting the decomposition of hazardous and refractory antibiotics.