Unraveling the enhanced electrocatalytic deactivation of dilute antibiotics on metal-free superhydrophobic porous biochar

Electrocatalytic hydrodechlorination (ECHD) represents a sustainable strategy for deactivating chlorinated antibiotics through hydrogenolysis of C Cl bonds. However, its widespread application is hindered by the scarcity of cost-effective catalyst, as well as their insufficient efficiency in treating trace antibiotics. Herein, a porous superhydrophobic biochar was fabricated from rice straw via a stepwise process of thermal pyrolysis, acidic etching and chemical reduction, which demonstrates an exceptional adsorption capacity of 575.0 mg g −1 for florfenicol (FLO) and a remarkable mass activity of 1.1 mg min −1 g −1 in ECHD of 20.0 mg L −1 FLO at −0.6 V. This performance not only exceeds reported biochars produced with fewer processing steps, but also surpasses several metal-based catalysts. Our biochar was further confirmed competent in degrading more dilute FLO (2 mg L −1 ) in contaminated lake water. Mechanistic investigations reveal that the outstanding ECHD performance of the biochar stems from its superhydrophobic and porous property, promoting adsorptive enrichment of trace antibiotics. In contrast, the carbon defects and oxygen-containing groups introduced during thermal pyrolysis impede electron transfer between the biochars and pollutants, due to unfavorable orbital occupancy, elevated work function and increased surface polarity within biochar. These findings emphasize the necessity of chemical reduction to remove these interfering moieties, while confirming the promise of porous and superhydrophobic biochars as sustainable catalysts for antibiotic-contaminated water remediation. • A metal-free superhydrophobic porous biochar is fabricated from rice straw • The biochar delivers exceptional adsorption capacity for florfenicol • The biochar is efficient and durable in deactivating dilute antibiotic pollutant • The robust performance of biochar stems from its porous and superhydrophobic property • Defects and oxygen-containing groups in biochar impede electron transfer to pollutant