Composite anode electrode based on iridium oxide promoter for direct methanol fuel cells

A composite anode was developed to increase the performance of a direct methanol fuel cell (DMFC). High surface area IrO2 nanopowder was synthesized by a sulfite complex method and added to a 50% PtRu/C catalyst prepared by the same procedure. A catalytic ink, composed of PtRu/C catalyst, IrO2 and Nafion ionomer, was deposited on a carbon-cloth-based backing layer and used as composite anode in a DMFC. A significantly higher performance was recorded for the composite electrode-based MEA compared to a bare one, at 60 °C and 90 °C, confirming that the electrocatalytic activity is related to the characteristics of water displacement of IrO2 additive, which acts as a co-catalyst for this reaction. The improvement was significantly higher by using 5 M methanol solution as the fuel. These results evidence that a multifunctional catalyst can operate better than PtRu for methanol oxidation since this multi-step process requires different functionalities to speed up the reaction rate.