Mechanistic Studies of Formate Oxidation on Platinum in Alkaline Medium

Abstract

The electro-oxidation of formate (HCOO–) on polycrystalline Pt in highly basic medium (pH = 14) has been investigated by cyclic voltammetry, differential electrochemical mass spectrometry, potential step-linear sweep voltammetry, and adsorbate stripping experiments. Low oxidation currents were observed for HCOO– oxidation indicating that HCOO– is only weakly active under these conditions. The activity of HCOO– is confined to low potentials (0.2 V < E < 0.7 V vs RHE). Our results suggest a dual pathway mechanism for HCOO– oxidation, analogous to HCOOH oxidation in acid. In the case of HCOO– oxidation, the direct and indirect pathway analogues are referred to as the primary and secondary pathways, respectively. Formation of COads from HCOO– was observed to be slow. We also find that oxidation of COads (the secondary pathway) is strongly coupled to the oxidation of HCOO– through the primary pathway. Moreover, the oxidation of COads did not appreciably enhance HCOO– oxidation through the primary pathway, sign...