Recent advances in porous structures for oxygen reduction reaction

As environmental concerns grow, there is a global shift from traditional fossil energy. Hydrogen fuel cells are gaining attention, but high material costs limit their adoption in large scale. The oxygen reduction reaction at the cathode of fuel cell, which dominates the electrochemical kinetics, relies mainly on platinum-group-metal (PGM) catalysts, hence research is focused on minimizing PGM or developing non-PGM catalysts. Porous materials possess unique physicochemical properties, and have shown great potential in advancing catalyst technology in fuel cells. This review summarizes the recent fundamental and technological advances of porous catalysts for oxygen reduction reactions including PGM and non-PGM catalysts, discusses the mechanisms underlying the enhanced catalytic activity through structural design and surface modification. It also highlights the comprehensive impact of porous materials in oxygen reduction reactions and membrane electrode assemblies, the main challenges, and provides perspectives on research of porous catalyst.