COMPARATIVE INVESTIGATION OF FORMIC-ACID AND FORMALDEHYDE ELECTROOXIDATION ON PALLADIUM IN ACIDIC MEDIUM - EFFECT OF SURFACE OXIDES

A comparative study of the electro-oxidation of HCOOH and HCHO on oxidized Pd electrodes was carried out by CV combined with oxidatin potential steps, chronopotentiometry and potential decay at open circuit. The HCOOH oxidation currents increased steadily when oxidation potential steps of increasing value were applied, provided that not very stable Pd oxides were formed. The opposite effect was observed for HCHO oxidation. Palladium oxides were chemically reduced by HCOOH but not by HCHO. The activating effect observed for HCOOH oxidation was associated with the chemical and electrochemical reduction of the less stable Pd oxides.