Heterogeneous Indirect Redox Electrocatalysis in Electrolyte.

Heterogeneous indirect electrocatalysis has emerged as a promising electrochemical transformation technology, demonstrating broad application potential in diverse molecular conversions. By utilizing heterogeneous redox mediators as electron shuttles or catalysts to promote efficient electron transfer and substrate activation, this approach effectively addresses critical challenges inherent in conventional electrolysis technologies such as high overpotential, low selectivity, electrode deactivation, and difficulty in catalyst recovery. Although novel indirect electrocatalysis systems mediated by heterogeneous redox media have been continuously developed, related comprehensive reviews are still rarely reported. Therefore, this review comprehensively summarizes the design concepts, system compositions (e.g., reactor, electrode, electrolyte and redox mediators), the type of heterogeneous redox mediators (e.g., foams, polymers, COFs, MOFs and POMOFs), and relevant catalytic applications of heterogeneous indirect electrocatalysis. Particular emphasis is placed on discussing the selection criteria, reaction mechanism and performance optimization strategies. Meanwhile, the characteristics, challenges, and perspectives of heterogeneous indirect electrocatalysis are reviewed, and their unsolved problems and possible developments are discussed.