Transition metal chalcogenides platinum-based materials

The intent of this chapter is to give readers a flavor of research into the ORR performed during three decades on transition metal chalcogenide materials. Although not discussed in this chapter, it is likely that the ORR arena is nowadays dominated by the platinum-based catalysts. But the issue of stability and activity as well as tolerance requirements for large-scale fuel cell application is still a matter that requires efforts of materials scientists, and therefore, it remains still a challenging aspect in ORR electrocatalysis. 

Normally, the kinetics of ORR and OER occurring at the cathode of fuel cells, including direct methanol fuel cells (DMFCs) is very slow. In order to speed up the ORR kinetics to reach a practical usable level in a fuel cell, ORR catalyst is needed at the air cathode. Platinum (Pt)-based materials are the most practical catalysts used in PEM technology. These Pt-based catalysts are too expensive to make fuel cells commercially viable, and hence extensive research over the past several decades has been focused on development of alternative catalysts. These alternative electrocatalysts include noble metals and allo37S, carbon materials, quinone and its derivatives, transition metal macrocyclic compounds, transition metal chalcogenides, transition metal carbides and transition metal oxides. In this chapter, we focus on both noble and nonnoble electrocatalysts being used in air cathodes and the kinetics and mechanisms O2 reduction/oxidation reaction (both ORR and OER), catal37zed by them. 

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