Engineered diatomic catalyst empowered electro-Fenton processes for advanced water purification

The heterogeneous electro-Fenton (EF) process has attracted tremendous interest as a promising advanced oxidation reaction to treat refractory organic contaminants in water. However, its practical application has been limited by unsatisfactory catalyst performance. Atomically dispersed metal catalysts are appealing for EF systems due to their high atomic utilization, intrinsic activity, and selectivity. In this review, we introduce the latest advances in metal-based single atom catalysts (SACs) for coordinating multiple oxygen reduction pathways in EF. First, we present a comprehensive summary of rational SAC design for selectively converting O to HO and ultimately to ˙OH in successive reactions, as well as the associated mechanisms. Subsequently, we delve into the design and synthesis principles of diatomic catalysts (DACs), highlighting their collaborative functions to direct selective O conversion to ˙OH. Finally, we conclude the review by discussing current challenges and further directions for the intelligent design of electrodes and reactors coupled with well-defined DACs for EF-based purification technologies.