β Scribed by M.R.H. Hill; C.E. Mellish
No coin nor oath required. For personal study only.
Abstmct-The relation between the oxide coverage of a platinum electrode and the adsorption of yttrium ions on to it has been studied in a system where both are measured without removing the electrode from the experimental solution. The oxide coverage was measured by reductive chronopotentiometry and the yttrium-ion adsorption radiometrically. The results of experiments performed between pH 3 and pH 5 demonstrate sharp differences of adsorption on to oxide formed in the potential regions @9-1.2, 1.2-1.6, and 164.8 V(he). Between 1.2 and 1.6 V the initial adsorption is proportional to oxide coverage, and independent of yttrium concentration, above a concentration of 5 x IO-' M. The adsorption in this potential range varies with time in a way that appears to reflect a m-organization of the surface oxide. R&sum&Etude de la relation entre le recouvrement d'oxyde B une electrode de platine et l'adsorption sur cette electrode des ions yttrium, obtenus au moyen d'un dispositif ou ils sont mesun% conjointement sans sortir l'electrode de la solution exp6riment6e. Le recouvrement d'oxyde a et6 obtenu par chronometrie et l'adsorption des ions yttrium, par radiom6trie. Les resultats trouves, entre pH 3 et pH 5 d6notent des differences nettes d'adsorption selon que l'oxyde est form6 dans les intervalles de potentiel 0,9-1,2; 1,2-1,6 ou l&-1,8 V. Entre 1,2 et 1,6 V l'adsorption initiale est proportiomrelle au recouvrement d'oxyde et independante de la concentration en ions yttrium, au dessus d'une concentration 5 . 10-' M. L'adsorption dans ce domaine de potentiel varie avec le temps dune man&e qui par& refleter une reorganisation de l'oxyde super8ciel. Zummmenfassmu-Die Bexiehung xwischen der Oxydbedeckung einer Platinelektrode und der Adsorption von Yttriumionen an ihrer OberlBiche wurde mittels einer Versuchsanordmmg untersucht, welche es gestattete, beide Brscheimmgen direkt in der Elektrolytliisung xu erfassen. Die Oxydbedeckung wurde durch reduktive Chronopotentiometrie, die Adsorption der Yttriumionen durch eine Tracer-Methode bestimmt. Die Resultate der xwischen pH 3 und pH 5 durchgeftihrten Versuche xeigen, dass die Adsorption am Oxyd vom Bildungspotential des Oxyds abhllngt. Es ergaben sich ausgeprllgte Unterschiede in der Adsorption fur die Potentialbereiche 0.9~1,2, 1,2-1,6 und 1,6-1.8 V (NWF). Zwischen 1,2 und 1,6 V ist die anf8ngliche Adsorption unabhlngig von der Yttriumkonzentration, falls diese grosser s roportional xur Oxydbedeckung und s 5 x lO+ M ist. Die Zeitabhlhrgigkeit der Adsorption in diesem Potentialbereich weist auf einen Umordnungsvorgang in der Oxydschicht bin.
π SIMILAR VOLUMES
The oxidation processes of cyanide and cyanate ions on a Pt electrode in aqueous and methanol solutions were studied by infrared spectroscopy. In aqueous solution, the cyanide ion was oxidized to cyanate and successively to carbon dioxide. The reaction proceeded on an oxidized platinum surface. In m
UsingXPS method it is shown t h a t the anodic charge transfer supported oxidation of platinum single crystal electrodes in aqueous 0.1 M HCIO, solution is influenced by the atomic! surface arrangements. The best electrode stability is received for the (111) surface with the largest atomic density i
Cyclic voltammetry experiments performed in acid solutions of cyclohexene on platinized platinum anodes show that platinum oxide must play a role in the anodic oxidation of the hydrocarbon through a mechanisticscheme of the type proposed by Gilman[lO].
The mechanism of anodic oxidation of cyanide on platinum electrode was studied electrochemically and chemically. Cyanide was oxidized at a first order with respect to hydroxyl ion and at zero with respect IO cyanide ion on the rate determining step. On the other hand. the potential controlled coulom