Electrocatalytic problems associated with the development of direct methanol-air fuel cells

Abstract

The potential advantages of the direct methanol-air fuel cell over conventional power sources are reviewed. The key to the successful development of such a device lies in the development of much more effective fuel and air electrode catalysts than are at present available. In this paper the problems associated with the electro-oxidation of methanol in acid electrolyte are reviewed. In particular the area of noble metal catalytic electrodes is discussed in some detail. The reaction mechanism and the build up of the poisoning intermediate that leads to dramatic losses of activity are discussed and potential electrolytes for methanol electro-oxidation are considered. The role of the second component in bimetallic catalysts is gone into in some detail and the activity of such catalysts is discussed. Attention is drawn to the role of catalyst preparation and activation conditions in determining catalytic activity and in particular the influence of catalyst metal crystallite size and metal-support interactions on activity is highlighted. In addition the long-term stability of methanol electro-oxidation catalysts is discussed. Finally areas where further progress may be made are pinpointed.