Carbon nanostructured catalysts as high efficient materials for low temperature fuel cells

Abstract

Low-temperature fuel cells are representative of environmentally friendly technologies, which enable directly produced electricity by converting the hydrogen/ methanol/ethanol and oxygen into water/water and carbon dioxide. Although these systems have low technical complexity, because of sluggish kinetics of oxygen reduction reaction (ORR), they need an efficient catalyst. Platinum and its alloys deposited on the carbon support were the first catalyst generations that have been extensively used as cathode electrodes because of their low overpotential as well as ability in four-electron reduction reaction. However, the stability of Pt-based catalysts and their cost are the two critical challenges that need to be considered for the successful commercialization. Thus, several researches have been done to find out a way to reduce the platinum amount in the catalyst of the low-temperature fuel cells. In this regard, several solutions have been proposed such as catalyst functionalization by transition metal oxides or using new carbon materials as catalysts supports. To overcome the platinum disadvantages such as low durability, poisoning effects, and crossover issues, nonprecious metal catalysts (NPMCs) with high oxygen reduction ability have become distinguished. In this regard, many materials were checked to reach the combination of ORR activity with good performance stability and economic consideration. In this chapter, firstly different mechanism pathways occurred in low temperature fuel cells will be discussed. Moreover, the advantage and disadvantage of different generations of carbon-based catalysts from Pt-based and its alloys up to nonprecious metal catalysts (metal containing and metal-free ones) used in low temperature fuel cells will be studied.