Hierarchical Iron Phosphides Composite Confined in Ultrathin Carbon Layer as Effective Heterogeneous Electro-Fenton Catalyst with Prominent Stability and Catalytic Activity

The heterogeneous electro-Fenton (EF) process is a promising wastewater treatment technology for the onsite production of H2O2 and avoidance of iron sludge. However, the preparation of the cathode catalysts remains a challenge. Not only must the catalyst surface possesses active sites for both 2e(-) oxygen reduction reaction and heterogeneous Fenton reaction, preventing active metals from continuous leaching is also crucial to maintain its catalytic activity. Herein, a heterogeneous catalyst (rGO@FexP/C) with a vacuumized package-like structure, where carbon-supported iron phosphides (FexP/C) are tightly covered within interconnected reduced graphene oxide (rGO) sheets, is successfully prepared. The concentration of iron that dissolved from rGO@FexP/C after the reaction is only 3.37% of bare FexP/C (14.6 mg L-1), while rGO@FexP/C achieves better performance towards sulfamethoxazole (10 mg L-1) degradation than FexP/C. Investigation on rGO@FexP/C with different thicknesses of outer rGO layer and diverse morphologic structures demonstrate that the unique structure of rGO@FexP/C played a decisive role in the simultaneously enhanced activity and stability.