Document Type

Article

Publication Date

2004

Journal or Book Title

Langmuir

Volume

20

Issue

5

First Page

1856

Last Page

1863

DOI

10.1021/la035567i

Abstract

Methanol electro-oxidation was studied on a series of electrodeposited PtxRuy catalysts constructed as multielement band electrodes. A combination of electrochemical and scanning differential electrochemical mass spectrometry measurements were performed to evaluate the composition-dependence of methanol oxidation, methanol decomposition, CO2 current efficiency, and the product distribution at 25 and 50 °C. At 25 °C, cyclic voltammetry revealed that the presence of Ru led to enhanced methanol oxidation rates over that of pure Pt. Methanol decomposition showed a similar composition-dependence. Mass spectrometry measurements revealed the evolution of HCOOH and CO2 during methanol oxidation and allowed indirect determination of H2CO produced. Notably, these products were not observed during methanol decomposition. The most active electrode compositions and the highest instantaneous current efficiencies for the formation of CO2 were found to depend on several factors. At 25 °C, the maximum activity was 10% Ru, while at 50 °C the most active composition increased to 25% Ru. Pure Pt had the highest instantaneous current efficiency for CO2 at both temperatures. The product distribution reflected high CO2 evolution for Pt, with an increasing fraction of the product emerging as H2CO at higher Ru content. Increasing the temperature improved the CO2 current efficiency for all electrode compositions. These results confirm that methanol oxidation occurs though a parallel reaction pathway on PtxRuy electrodes. In addition, the balance between the different reaction pathways depends on several factors, including Ru composition and temperature.

Comments

This article is from Langmuir20 (2004): 1856-1863, doi: 10.1021/la035567i. Posted with permission.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

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