Abstn~ct--Anodic and catalytic oxidations of formate ion at an active Pd electrode were studied by the potential-sweep and the galvanostatic methods in connexion with the measurements of the rate of formation of hydrogen on Pd during the catalytic decomposition of formate. A Pd surface oxidized by pre-anodization is reduced with ease by dissolved formate. Formate adsorbed on the cleaned surface decomposes into two fragments such as Haa andCO& throughthereactionHCOI--+ Had + CO&. On standing, CO&a is oxidized further by OH-to C08*-and I&&
In the absence of polarization, the net reaction of the catalytic decomposition is HCO$-+ OH--+ COs*-+ 2 Had. Presence of I& on Pd hinders this reaction to some extent, but hydrogen evolution could be observed at high electrolyte concentrations.
The net reaction of anodic oxidation of formate is HCO*-+ 3 OH-+ CO,'-+ 2 HpO + 2 e, in which reactions such as H&d + OH-+ Ha0 + e and CO&d + 2 OH-+ CO,*-+ H,O + e are involved. The nature of the open-circuit voltage in this system is examined by taking these species into consideration. Rbumb-Les oxvdations anodiques et catalytiques des ions de formiate rl une Pd &&ode active ant &t+ &udi&s par le balayage hotentiel et ia ri%thode galvanostatique en connexion avec la mesure du taux de formation de l'hvdrodne sur Pd uendant la dbcomuosition catalvtiaue de formiate. Une surface de Pd oxydQ sous pte-a&isation pe& &tre reduite ai&nent avec pddu'formiate dissous. Le formiate absorb& sur la surface rendue propre se d&ompose en deux fragments tels que H.4 et CO& par suite de la r&action, HCO,-OH-en CO, et HM. + Had + CO&. Etant rest&, COTad est encore oxyd6 par En l'absence de polarisation, la r&action nette de la decomposition catalytique est rep&en&. par HCO,-+ OH-+ CO, a-f 2 Ha. La presence de I& sur Pd emp&che cette r&&on jusqu'b un certain point, mais une 6volution de l'hydrog6ne gazeux a pu Btre observ6e B hautes concentrations Bectrolytiques. La r&&ion nette d'oxydation anodique du formiate est HCO,-+ 3 OH-+ C08* + 2 He0 + 2 e, dans laquelle les r&&ions telles que I& + OH-+ H,O + e et CO, + 2 OH-+ CO,*-+ Ha0 + e sent considkr&s comprises. La nature de la tension en circuit ouvert dans ce syst&me a &5 examin& en prenant ces esp&ces en considkration.