Introduction
Significant efforts in recent decades have been focused on the direct electrochemical
oxidation of alcohol and hydrocarbon fuels. Organic liquid fuels are characterized by
high energy density, whereas the electromotive force associated with their electrochemical
combustion to CO2 is comparable to that of hydrogen combustion to
water [1–3]. Among the liquid organic fuels, methanol has promising characteristics
in terms of reactivity at low temperatures, storage and handling. Accordingly, a
methanol-feed proton exchange membrane fuel cell (PEMFC) would help to alleviate
some of the issues surrounding fuel storage and processing for fuel cells. Technological
improvements in DMFCs are, thus, fuelled by their perspectives on applications
in portable, transportation and stationary systems especially with regard to the
remote and distributed generation of electrical energy [4, 5]. Methanol is cheap
and can be distributed by using the present infrastructure for liquid fuels. It can be
obtained from fossil fuels, such as natural gas or coal, as well as from sustainable
sources through fermentation of agricultural products and from biomasses. Compared
with ethanol, methanol has the significant advantage of high selectivity to CO2
formation in the electrochemical oxidation process [1–3]. However, despite these
practical system benefits, DMFCs are characterized by a significantly lower power
density and lower efficiency than a PEMFC operating with hydrogen because of the
slow oxidation kinetics of methanol and methanol crossover from the anode to the cathode.