Platinum Metals Rev., 1962, 6, (1), 8
Platinum Catalysts in Fuel Cells
Advantages of Low Temperature Operation
The immense amount of research now being carried out on the development of fuel cells is directed towards a considerable variety of devices. The possible combinations of fuels, electrodes and electrolytes are obviously very numerous, even within the limits of potential practicability, and the range covered by both industrial and government sponsored research programmes is extremely wide. Naturally there is no expectation of the development of one all-purpose fuel cell, and it is likely that a number of differing types, each with its own particular advantages and shortcomings, will emerge within the next few years to meet the varied requirements of vehicular propulsion, communications, auxiliary power sources in aircraft and specialised military applications. The day of the fuel cell as a means of primary power generation is certainly farther away.
While research on cells aimed at central station generation is generally based upon operation at more or less elevated temperatures, there is an obvious advantage in the achievement of low temperature operation for cells designed to provide auxiliary power or to operate in locations remote from sources of heat. This lies in the ease of starting-up at normal temperature. Now in most types of fuel cell it is essential to incorporate a catalyst in the electrodes to achieve a high rate of reaction. In cells operating at elevated temperatures a catalyst of only moderate activity is adequate to ensure rapid reaction, depending, of course, upon the particular fuel employed and upon the structure of the electrodes. With lower temperatures of operation a more highly active catalyst - and one resistant to poisoning by impurities in the fuel - must be chosen.
An increasing number of fuel cell designs currently being investigated employ platinum, or sometimes another member of the platinum group, dispersed on or in the structure of the electrode in conjunction with one or other of a variety of fuels such as hydrogen, hydro carbons and alcohols. Although in some cases precise details of the catalyst are not disclosed, a trend clearly discernible in the vast amount of research now in progress is towards the high degree of acceleration of the electrode reaction that can be provided by a platinum catalyst, operating at ambient temperature and with an organic fuel that can be made available cheaply in a state of high purity.