Synthesis and Evaluation of Carbon supported Palladium based materials for Direct Methanol Fuel Cell (DMFC) operating at high methanol concentration

Next generation cathode catalysts for direct methanol fuel cells (DMFCs) must have high catalytic activity for the oxygen reduction reaction (ORR), a lower cost than benchmark Pt catalysts, and high stability and high tolerance to permeated methanol. 30% Pd on Ketjenblack (labelled as KB) and 30% Pd4Co1/KB were prepared using the sulphite complex route [1]. Samples were physico-chemically characterized and the electrochemical performance was investigated. Electrochemical tests were carried out in half cell and DMFCs to evaluate the performance, the methanol tolerance and the durability of the prepared electrocatalysts. For comparison, a benchmark 30% Pt/C catalyst was also tested at the cathode of the DMFC, under the same conditions and with the same noble metal loading. The high methanol tolerance properties of Pd and Pd-alloy based electrocatalysts, as evidenced in the half cell characterization [2], were also demonstrated in DMFC. The advantage of using a high methanol concentration in DMFCs is related to a higher energy density. On the other side, methanol crossover reduces the overall efficiency. Thus, Pd-based electrodes represent a reliable way to minimize the cost in low temperature fuel cells, providing a higher performance than that of Pt-based electrodes at high methanol concentration. The durability tests highlight the advantage of including cobalt in the crystalline structure of Pd, in terms of resistance to corrosion phenomena, pointing to a powerful candidate cathode material for Direct Methanol Fuel Cells (DMFCs).