The electrochemical behavior of cobalt phthalocyanine/platinum as methanol-resistant oxygen-reduction electrocatalysts for DMFC

The electrochemical behavior of cobalt phthalocyanine/platinum as methanol-resistant oxygen-reduction electrocatalyst for DMFC was investigated. Platinum was chemically deposited on the carbon-supported cobalt phthalocyanine (CoPc), and then it was heat-treated in high purity nitrogen at 300 °C, 635 °C and 980 °C. In order to evaluate the electrocatalytic behavior of CoPc-Pt/C, the PtCo/C and Pt/C as reference catalysts were employed. TGA, XRD, EDAX, XPS and electrochemical experiments were used to study the thermal stability, crystal structure, physical characterization and electrochemical behavior of these catalysts. These catalysts exhibited similar electrocatalytic activity for oxygen reaction in 0.5 M H₂SO₄ solution. In methanol tolerance experiments, Pt/C, PtCo/C and CoPc-Pt/C heated at 980 °C were active for the methanol oxidation reaction (MOR). The presence of Co did not improve resistance to methanol poisoning. However, the CoPc-Pt/C after 300 °C or 635 °C heat-treatment demonstrated significant inactivity for MOR, hence they have a good ability to resist methanol poisoning. The current study indicated that the macrocyclic structure of phthalocyanine is the most important factor to improve the methanol tolerance of CoPc-Pt/C as the oxygen-reduction reaction (ORR) electrocatalyst. The CoPc-Pt based catalyst should be a good alternation for oxygen electro-reduction reaction in DMFC.