Methanol Oxidation on Ru- or Ni-Modified Pd-Electrocatalysts in Alkaline Media: A Comparative Differential Electrochemical Mass Spectrometry Study

Abstract

In this work, the methanol oxidation mechanism was investigated in detail on Ru- or Ni-modified, Pd-based electrocatalysts. The electrochemical activity towards methanol oxidation reaction, the surface inhibition behavior and the CO2 current efficiency was evaluated for the catalysts by cyclic voltammetry, chronoamperometry, CO adsorbate stripping and CH3OH adsorbate stripping experiments in a differential electrochemical mass spectrometry flow cell setup. Pd5Ni/C and Pd3Ru/C catalysts showed higher current densities, lower oxidation onset potentials and lower sensitivity to surface inhibition than Pd/C. Due to detailed studies on the CO2 current efficiencies, side products and adsorbate reactions via differential electrochemical mass spectrometry, novel insights into the electrooxidation of methanol on Pd5Ni/C and Pd3Ru/C were provided. While modification with Ru resulted in CO2 current efficiencies well over 80%, Ni-modified catalyst was not able to enhance the CO2 current efficiency.