Preparation of N and Ce Co-doped MIL-101(Fe) Heterogeneous Catalysts for Efficient Electro-Fenton Oxidation

Design and synthesis of high-efficiency and stable heterogeneous catalysts for the electro-Fenton process remain challenging. In this study, a co-doped Ce and N metal–organic framework MIL-101(Fe) heterogeneous catalyst (Ce/N-MIL-101(Fe) was synthesized by a facile one-step solvothermal method. Polyvinyl pyrrolidone played dual roles during the fabrication process, which not only acted as a nitrogen source for doping but also prevented MIL-101(Fe) molecules from aggregating and reinforcing the formation crystal with a complete polyhedral crystal shape. The introduction of Ce significantly enhanced the density of active sites and promoted the Fe3+/Fe2+ cycle of the reaction system. Owing to the specific structure and properties, the rate of electron transfer in the catalytic process was significantly promoted. The synthesized Ce/N-MIL-101(Fe) catalyst exhibited a high degradation rate for dyes (>98%) with competitive stability and reusability. Moreover, compared with common electro-Fenton catalysts usually operated in a limited pH range of 3.0–6.0, the working pH range of Ce/N-MIL-101(Fe) was widened up to 10.0. The design concept for producing abundant active sites with co-doping into frameworks can be extended to more heterogeneous electro-Fenton catalysts constituted by other porous materials.