Recent Advances and Prospective Challenges of Iron Metal–Organic Framework (MOF) Catalysts in Electrochemical Fenton Treatment Technologies

Electrochemical advanced oxidation processes have emerged as a promising technology to efficiently remove recalcitrant organic pollutants. Electro-Fenton (EF) processes are highlighted due to fast reaction kinetics, facile operating parameters, and low energy consumption. Nanomaterials with competitive surface area and catalytic activity, such as metal–organic frameworks (MOF), are being explored as catalysts to make the EF treatment process more effective. This paper reviews the recent trends in implementing iron-based MOFs in electrochemical Fenton-based technologies while highlighting needed improvements to further bolster their potential for industrial application.

The majority of early research to design iron-based MOF catalysts has utilized MOF pyrolysis to design catalysts that outperform traditional iron catalysts in terms of stability and degradation efficiency. Research focus has now shifted to designing stable pure MOF catalyst material instead of MOF-derived catalysts for EF treatment, often by complementing iron with the addition of a second metal. Designing pure iron–based MOF catalysts that can be employed directly in suspension instead of embedded upon a cathode can simplify catalyst synthesis and application, bolstering their potential for industrial use. These new methods have demonstrated efficacy in both acidic and basic pH operating conditions while extending the life cycles of catalysts to achieve high removal of trace pharmaceuticals and organic dyes. Despite this, factors such as complicated synthesis and limited understanding around catalyst stability in realistic water conditions still present concern for further research improvement.

This study explores how iron-based MOFs have been used to enhance as a competitive catalyst for both electro-Fenton and heterogeneous photoelectro-Fenton (HPEF) processes for water/wastewater treatment, but other engineering considerations such as reusability and operating conditions must be improved to advance this emerging process towards higher technology readiness levels. Through this study, current research is critiqued to provide a research roadmap towards successful MOF catalyst implementation.