“…However, metal-based catalysts, particularly noble metals such as platinum, iridium, and palladium, suffer from significant drawbacks, including high cost, low selectivity, poor durability, susceptibility to gas poisoning, and negative environmental impact [25] . As a result, metal-free catalysts, such as carbon-based materials and conducting polymers, have emerged as promising alternatives to platinum catalysts, offering enhanced efficiency at a lower cost in many fields [26,27] . This section presents a comprehensive overview of metal-free catalysts in MES cathodes, specifically focusing on carbon-based materials and conductive polymers, which have been utilized as modifications to enhance cathode performance.…”