Traditionally, platinum (Pt) and its alloys have been the benchmark catalysts for ORR due to their excellent activity and stability. However, the high cost and scarcity of platinum drive the search for alternative catalysts. Non-precious metal catalysts, such as transition metal oxides, nitrides, and carbides, as well as carbon-based materials like doped graphene and carbon nanotubes, are being extensively studied for their potential to offer cost-effective and efficient ORR catalysis.
