High-Entropy Alloy Nanoparticles/Biochar as an Efficient Catalyst for High-Performance Treatment of Organic Pollutants

High entropy alloys (HEA) have recently emerged as a new class of single-phase solid solution materials and attracted widespread attention due to their unique physical and chemical properties. In this work, high entropy alloys/biochar (HEA@BC) were successfully prepared using alkaline lignin to derive biochar in concept of waste recycling. Benefiting from the unique multi-metallic composition and entropy-stabilized structure, HEA@BC exhibited excellent catalytic activity for the degradation of organic pollutants via peroxymonosulfate (PMS) activation and showed superiority compared with pure BC and monometallic catalyst. With ofloxacin (OFX) as a typical antibiotic pollutant, the HEA@BC/PMS system could achieve 98.2% degradation efficiency within 90 min. Quenching experiments and electron spin resonance (ESR) results revealed a radical/nonradical combined degradation pathway, in which 1O2 may play a dominate role. Mechanistic study demonstrated that the five components all participated in the catalytic process with Co and Cu considered to be the main active sites. The outstanding catalytic performance of HEA@BC could be attributed to the synergistic effects between each metallic component and graphitized carbon matrix to accelerate the electron transmission. According to the analysis of oxidation products, the major degradation pathways for OFX were proposed and the quantitative structure-activity relationship (QSAR) predictions revealed that the degradation process can reduce toxicity gradually. The study may give new insights into the design and preparation of high entropy catalysts which highlight promising applications for organic wastewater treatment.