Heat-treated non-precious-metal-based catalysts for Oxygen reduction

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.