Bifunctional catalysts for heterogeneous electro-Fenton processes: a review

Abstract Fenton processes allow to degrade and mineralize toxic organic contaminants, yet classical require continuously adding hydrogen peroxide ferrous ions, costly solution pH adjustment, treatment of secondary iron sludge pollution. Heterogeneous electro-Fenton deliver oxidizing radicals with only oxygen electricity consumed. Bifunctional catalysts the synthesis activation simultaneously, eliminate additional chemical reagents, yield no metal residues in treated water. Here, we review bifunctional for heterogeneous processes. We describe mechanisms radical generation from oxygen. Then, compare different types based on their elemental compositions: (1) metal/carbon composite catalysts, i.e., monometallic iron/carbon bimetallic/trimetallic carbon transition single-atom catalysts; (2) without carbon; (3) metal-free catalysts. present five other approaches beyond electrocatalysts, which have been used improve performance