Cesar Sequeira

Abstract:

Fuel cells are electrochemical devices that transform directly the chemical energy of a fuel into electricity. Thereafter, significant attention of the research community is devoted to the development of different types of fuel cells for a wide range of applications, from space programs to portable electronic devices, depending on their nominal power. Though hydrogen is the most suitable fuel for various applications, it does not exists in nature as such and its clean, large-scale production, storage and distribution are severe drawbacks for the development of hydrogen-fed fuel cells. In this context, liquids fuels like alcohols are more suitable as their storage, handling, and distribution are significantly simpler. Consequently, alcohols are seen as possible alternative fuels, having additional advantages of high energy density and possibility of being produced from renewable sources. Direct methanol fuel cells and direct ethanol fuel cells represent proton exchange membrane fuel cells operating with methanol and ethanol as fuel, respectively. Herein, working thermodynamic and kinetic principles of a fuel cell, as well as the electrocatalysis and the rate of fuel cell oxidation and reduction reactions, will be discussed. Furthermore, the main characteristics of methanol and ethanol fuel cells will be presented. In particular, some of the most important issues that hinder the development of commercial direct alcohol fuel cells are described along with the effect of various parameters on the cells performance. Clearly, the most complex challenge for cell operations is the slow oxidation and reduction kinetics, requiring development of highly electrocatalytically active electrode materials. This question is also addressed, but a more detailed discussion is provided in another symposium’s lecture on materials for fuel cells.