Effect of sulfate adlayer on formic acid oxidation on Pd(111) electrode

Jing Lei, Zhen Wei, Mian Le Xu, Jie Wei, Yan Xia Chen, Shen Ye

Research output: Contribution to journalArticlepeer-review

Abstract

The kinetics of formic acid oxidation (FAO) on Pd(111) in 0.1 mol/L H2SO4+0.1 mol/L HCOOH with and without addition of Na2SO4 is studied using cyclic voltammetry and potential step method, which is compared with that in 0.1 mol/L HClO4. It is found that adsorbed sulfate has significant inhibition effect on FAO kinetics. After addition of 0.05 mol/L or 0.1 mol/L Na2SO4, FAO current in the negative-going scan is found to be significantly smaller than that at the same potential in the positive-going scan. We speculate that at potentials positive of the phase transition potential for the (SO4ad*)m+[(H2O)n-H3O+] or (SO4ad)m+[Na+(H2O)n-H3O+] adlayer, the adlayer structure probably becomes denser and more stable with the increase of potential or with the addition of Na2SO4. The formation of connected adlayer network greatly enhance the stability of the adlayer, and the insertion of positive-charged H+ or Na+ into the adlayer network further reduces the electrostatic repulsion between partially charged sulfates. As a result, the destruction/desorption of compact sulfate adlayer becomes more difficult, which leaves much less free sites on the surface for FAO, and thus FAO kinetics at higher potentials and in the subsequent negative-going potential scan is significantly inhibited.

Original languageEnglish
Pages (from-to)649-656
Number of pages8
JournalChinese Journal of Chemical Physics
Volume32
Issue number6
DOIs
Publication statusPublished - 2019 Dec 1

Keywords

  • Anions effect
  • Formic acid oxidation
  • Pd(111) electrode
  • Sulfate adsorption

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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