On the origin of Bi species deposited on Pt in non-linear electrocatalytic oxidation of HCOOH

초록

We understood the origin of bismuth (Bi) species deposited on platinum (Pt) electrode in non-linear electrocatalytic oxidation of formic acid (HCOOH). In cyclic voltammetry of Pt modified Bi ad-atoms, three distinct features of current-potential curves were observed. Bi oxidation process and re-deposition on anodic scan and cathodic scan induced periodic current oscillation presenting much higher current value compared with that on pure Pt electrode. Analysing in-situ surface mass change and electrode admittance data, we concluded that the Bi metal desorbed from the surface as form of soluble Bi (III) oxide via Bi (II) oxide. Current oscillation was strongly dependent on the coverage of Bi species and oxidation state of Bi, while the role of CO poising for the occurrence of oscillations could be neglected, because direct oxidation of HCOOH was mainly occurred on Pt surface modified by Bi.