Electrooxidation of formate and formaldehyde on electrodes of alloys between Pd and Group IB metals in alkaline media: Part II. The possibility of complete oxidation of formaldehyde in weak alkali

Abstract

The possibility of complete electrooxidation of formaldehyde on Pd + IB alloy electrodes was studied in K 2CO 3 solution. Formaldehyde is oxidized first to formate and hydrogen intermediate, and the latter is oxidized simultaneously on the electrodes provided that their Pd content is more than ~ 20 at.%. The rates of individual oxidation of HCOO − and HCHO become roughly equal to each other at a bulk Pd content of 50–60, 20–30 and 0–10 at.% for Pd + Cu, Pd + Ag and Pd + Au alloys, respectively. The oxidation of formate is, however, strongly retarded by the presence of formaldehyde. This retardation is least serious on Pd + Au alloy electrodes with 40–70 at % Pd, and thus they exhibit the highest electrocatalytic activity among Pd + IB alloys towards the oxidation of HCOO − to carbonate in HCOO − + HCHO mixed solution.