Investigation of methanol electrooxidation on Pt and Pt-Ru in H_3PO_4 using MEA with PBI-H_3PO_4membrane

摘要

Electrochemical oxidation of methanol on Pt/C and Pt-Ru/C electrocatalysts was studied by slow scan rate voltammetry at 130-190 C. The effects of partial pressures of water, methanol, and CO on the methanol electrooxidation rate were determined. It was found that methanol oxidation on Pt-Ru/C proceeds pri-marily via the "indirect" route through the formation of strongly adsorbed intermediate CO_(ads), while on Pt methanol electrooxidation occurs primarily via "direct" route through the formation of weakly adsorbed intermediates. At 140℃ activity of Pt-Ru/C in methanol electrooxidation was found 2 orders of magnitude higher than that of Pt/C. Methanol oxidation reaction orders per water and methanol vapor pressures were determined. The main features of methanol electrooxidation both on Pt and Pt-Ru were accounted for assuming Langmuir-Hinshelwood mechanism of respective RDS.