The impact and performance of carbon-supported platinum group metal electrocatalysts for fuel cells

Due to its high energy density and high combustion temperature, hydrogen (H2) is being investigated as a potential energy carrier to compete with and replace fossil fuels, yet its evolution requires the employment of efficient catalysts in liquid organics as its sources. These liquid organics include methanol and ethanol. The latter gains preference due to its low toxicity. To have an efficient fuel cell system, carbon-supported platinum group metal (PGM)--based catalysts are usually employed as these types of catalysts exhibit superior catalytic properties. The inclusion of catalytic carbon supports is important for the reduction of agglomeration in the PGM-based catalysts while also improving and enhancing the electron transfer processes. These catalysts, in turn, can be used to fabricate energy conversion devices and reactors such as proton exchange membrane fuel cells (PEMFCs) and direct alcohol fuel cells (DAFCs) to name a few. DAFCs, in particular, are more easily handled and have higher power output than proton exchange membrane fuel cells (PEMFCs) and have better efficiency, lower emissions when compared to other conventional energy technologies, simple design with no moving parts, and promising low-cost and durability. However, the system is constrained by various challenges such as slow kinetics of the methanol oxidation, crossover, and anode poisoning by strongly adsorbed intermediates. Thus, carbon supports come into play in these systems. In this review, we discuss the performance of various carbon-supported PGM-based catalysts in the as-fabricated PEMFCs, DAFCs, and DMFCs.