Electrocatalysis of Cathodic Oxygen Reduction and Anodic Hydrogen Oxidation in Fuel Cells

Electrocatalysis of Cathodic Oxygen Reduction and Anodic Hydrogen Oxidation in Fuel Cells 

According to the electrolyte and working temperature, one distinguishes the low-temperature fuel cell technologies (i) alkaline fuel cell, AFC (70 to 80°C), (ii) proton exchange membrane fuel cell, PEMFC (70 to 80°C), (iii) phosphoric acid cell, PAFC (200°C) from the high-temperature technologies, (iv) molten carbonate fuel cell, MCFC (650 to 700°C), and (v) solid oxide fuel cell, SOFC (1000°C). 

All these cells are anodically combusting hydrogen, although MCFCs and SOFCs may be supplied with methane or carbon monoxide from which by internal reforming and/or shift reaction with steam within the cell the hydrogen may be generated in situ (98-100). 

Anodic hydrogen oxidation and even more cathodic oxygen reduction is kinetically hampered at low temperature, so that anodic hydrogen oxidation in AFCs, PEMFCs, and PAFCs demands catalysts of highest activity, that is, platinum metals and platinum in particular. Also Raney nickel is used in 

Working temperatures of MCFCs and SOFCs, however, are high enough that the cheaper nickel metal—a much poorer catalyst than Pt—can be used. 

---