Fuel cells are energy conversion devices that offer the promise of higher efficiencies and greatly reduced emissions, compared to internal combustion engines. Consequently, an application of major interest for these devices is the electric vehicle (EV). However, present-day fuel cells typically operate on H2, so either a H2-storage device or a fuel reformer must be carried onboard the vehicle. Each of these H2-delivery options results in a heavy, bulky, and costly power plant. Therefore there exists a strong need for a fuel cell that can electrochemically oxidize liquid fuels, and the successful development of a direct-methanol fuel cell (DMFC) would represent a major advance.
For vehicle applications, only the polymer and alkaline electrolyte fuel cells are considered to be practical because of their low operating temperatures, i.e. they are capable of rapid start-up because they operate below 150C. The polymer electrolyte fuel cell is an attractive candidate for EV applications, however permeation of CH3OH through the electrolyte significantly degrades its fuel efficiency and performance. The formation of undesirable reaction products and cathode deactivation also reduce the overall performance of fuel cells with acidic electrolytes. The desired reaction products from the electrochemical oxidation of CH3OH are H2O and CO2. Our recent results demonstrated that the direct electrochemical oxidation of CH3OH on supported Pt/Ru alloy electrocatalyst occurs with a polarization comparable to Pt supported on carbon, but at a lower temperature.
We plan to improve DMFC performance by optimizing the overall design and varying the composition of the electrodes and the electrolyte. Recently, we have developed a new electrocatalyst synthesis procedure that allows us to prepare Pt alloy compositions not accessible by other methods in high-area form suitable for use in fuel cell electrodes. New electrocatalyst compositions are being prepared for study in direct methanol fuel cells, and in our NMR cell as described below.
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Striebel KA, McLarnon FR, Cairns EJ. Steady-state model for an oxygen fuel cell electrode with an aqueous carbonate electrolyte. Ind. & Engin. Chem. Res. 1995; 34: 3632.