Abstract and subjects
Non-precious metal catalysts have shown good activity towards oxygen reduction reaction, both in basic and acidic media. The use of NPMCs in fuel cells and metal–air batteries has been hampered by two main issues: the synthesis complexity, translating into a high fabrication cost, and by relatively low stability when compared to platinum-based catalysts, especially in acidic media. In order to overcome these issues, a new class of non-precious metal oxygen reduction catalysts was developed that involves heat treatment as a key step in the NPMC synthesis. This chapter provides a review of the progress in research on heat-treated non-precious metal catalysts of oxygen reduction since the early 1970s until today. The focus of this chapter is on the activity and morphology of the state-of-the-art heat-treated ORR catalysts and trends in the development of more active and durable materials.