Non-Noble Metal Electrocatalysts for the Oxygen Reduction Reaction in Fuel Cells

Abstract

Low temperature fuel cells are promising and sustainable alternative in energy generation. However, their large-scale production have been limited due at high-cost and scarce electrocatalysts based commonly in noble metals. Development of non-noble electrocatalysts has become intensive in recent years. A wide variety of materials as perovskite-type, spinel-type oxides, tungsten carbides, and heteroatom-doped carbons has been explored as alternative electrocatalysts to platinum. They have demonstrated promising electrocatalytic activity toward the oxygen reduction reaction (ORR) in alkaline electrolytes. However, these electrocatalysts are not favorable using strong acid electrolytes. Moreover, transition metal macrocycles show activity performance close to those of Pt-based electrocatalysts in acid media. In this chapter, we present the most recent developments regarding non-noble metal electrocatalyst, starting with a review of some basic electrochemistry concepts and some techniques commonly used to evaluate their performance. Then, materials used as non-noble metal electrocatalyst are presented which are divided into two groups: (1) the most promising non-noble metal electrocatalysts used in acid electrolytes and (2) in alkaline media. Finally, the conclusions and futures perspective are mentioned for these materials that should be considered as the future electrocatalysts for sustainable large-scale fuel cell commercialization.