Anode materials, alternative/modified

Alternative or Modified Anode Materials In order to prevent or minimize thermal runaway, modified anode materials can also be considered. The minimum energy for a dust ignition in the case of pure Ta or Nb powder is below 3 mj. Nitration of Ta and Nb (e.g. TaN and Ta2N) increases the ignition energy to >10 J. Consequently, these materials are also less likely to be prone to ignition in solid capacitors. These... 

The permeation of methanol through the membrane from the anode to the cathode (cross-over) represents a source of severe performance loss. The combined reaction of methanol and oxygen on the cathodic platinum catalysts (or platinum-based alloys) leads to a mixed potential formation that reduces the maximum achievable potential considerably by up to 200 mV. Two strategies are followed to circumvent this phenomenon. On the one hand the general avoidance of methanol permeation through the membrane allows the use of standard catalysts. The other strategy is the use of methanol-tolerant catalysts for the cathode of DMFCs these materials are characterized by a complete inactivity towards methanol, which does not react on these catalyst surfaces. For the development of methanol-tolerant catalysts, several prerequisites have to be fulfilled to obtain competitive products the new material not only has to be as active as a comparable catalyst (platinum-based) but also the stability and cost aspect have to be considered. Recently, selenium-modified rathenium particles (RuSe ) were found to be a suitable alternative to platinum-based alloys where the addition of selenium increases the activity of pure rathenium particles to shift these catalysts in a competitive regime. ... 

There has been considerable research on modifying Nafion and novel development of membranes, so as to improve its properties for use in a DMFC. Despite advancement in the development of DMFCs, severe restrictions still inhibit their laige-scale commercialization due to the deficient of appropriate membrane materials. Nafion membranes that still dominate the maiket of PEMs allow methanol permeation from the anode to the cathode of a DMFC, resulting in serious negative consequences. Three approaches have been pursued in order to resolve the methanol permeation problem (1) modification of Nafion membranes, (2) development of alternative membranes, and (3) provision of high activity anode catalysts or methanol tolerant cathode catalysts. 

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