Direct methanol fuel cell reaction models

PEMFC)/direct methanol fuel cell (DMFC) cathode limit the available sites for reduction of molecular oxygen. Alternatively, at the anode of a PEMFC or DMFC, the oxidation of water is necessary to produce hydroxyl or oxygen species that participate in oxidation of strongly bound carbon monoxide species. Taylor and co-workers [Taylor et ah, 2007b] have recently reported on a systematic study that examined the potential dependence of water redox reactions over a series of different metal electrode surfaces. For comparison purposes, we will start with a brief discussion of electronic structure studies of water activity with consideration of UHV model systems. 

Other similar cases exist, such as direct electro-oxidation of alcohols such as methanol and formic acid in low-temperature fuel cells. In these cases, an alternative to the BV formulation that accounts for the limiting adsorption and charge transfer steps is appropriate. Two common models for a surface adsorption limited reaction are the Langmuir and Temkin kinetics. In the simpler Langmuir model, the surface adsorption rate constant is independent of surface coverage. In the Temkin model, the adsorption rate constant is modeled as a function of the surface coverage of adsorbed species. In both models, a two-step reaction mechanism is assumed [6] ... 

---