Effectively controlling the nanostructures and active sites of non-noble carbon catalysts for improving oxygen reduction reaction

Non-noble carbon catalysts have emerged as the potential alternatives of precious platinum (Pt)-based catalysts to catalyze the cathodic oxygen reduction reaction (ORR) in fuel cells and metal-air batteries. However, their catalytic performance including ORR activity and stability is still insufficient for the practical application of such electrochemical energy technologies. Both the activity and stability of such ORR electrocatalysts correlate quite well with their nanostructure control and active sites, therefore, it is necessary to fundamentally understand the relationship of the macroscopic material morphologies and microscopic active sites with the catalytic performance. This review summarizes a critical overview of the recent progress and perspectives of non-noble carbon catalysts, ranging from the classification of material morphologies and identification of active sites to the understanding of structure effects on catalytic ORR performance.