Investigation of Pt-Fe catalysts for oxygen reduction in low temperature direct methanol fuel cells

摘要

High surface area carbon supported bimetallic Pt-Fe catalysts have been investigated for the oxygen electro-reduction process in low temperature direct methanol fuel cells (30-60 deg C). The electrocatalysts have been prepared by using a combination of colloidal and incipient wetness methods allowing of synthesis carbon supported bimetallic nanoparticles with a particle size of about 2-3 nm. These materials were studied in terms of structure, morphology and composition using XRD, XRF and TEM techniques. Oxygen reduction properties of these bimetallic catalysts were investigated in single cell DMFC polarizations. The electrochemical data were compared with those obtained in the presence of a Pt/C catalyst prepared by the same procedure and characterised by the same concentration of active phase on the carbon support and a similar particle size. An improvement of the DMFC single cell performance was observed in the activation controlled region in the presence of the bimetallic catalysts. Moreover, the influence of the ionomer loading on the performance of the DMFC was investigated. The highest power density was recorded with electrodes containing 25 percent Nafion loading (87 mWcm~2).