Hierarchical iron phosphides@hard carbon composite cathodes for phenol degradation by highly efficient heterogeneous electro-Fenton

Heterogeneous electro-Fenton is a promising wastewater treatment technology that can efficiently degrade organic pollutants without secondary pollution. However, challenges persist in developing streamlined synthesis methods for high-performance, cost-effective cathode catalysts. Herein, hierarchical iron phosphides@hard carbon composites with porous heterostructures were engineered through a synergistic approach involving high-temperature calcination, chemical activation, and iron phosphide doping. It features effective doping of FeP nanoparticles, a relatively high specific surface area, and abundant catalytically active sites. The optimal catalyst achieved 95.4 % phenol degradation within 180 min under neutral conditions, coupled with 61.4 % chemical oxygen demand (COD) removal. Notably, the system maintained 90.0 % phenol removal efficiency over 20 recycling times, far exceeding some reported cathodes. A key advancement lies in the catalyst's broad pH adaptability (pH 3–9), effectively eliminating the stringent pH limitations (typically pH 2–4) inherent to traditional homogeneous electro-Fenton systems. The superior performance of the composite catalyst demonstrates the viability of biomass-derived hard carbon for wastewater treatment and offers a novel reference for its application in the realm of electro-Fenton degradation.