Role of gas bubbles adsorbed on a carbon electrode: electroreduction of chlorine gas in fused salts

摘要: The reaction Cl2+2e ⇔ 2Cl− has been studied by transient electrochemical techniques on a vitreous carbon electrode in fused alkali chlorides. Two regimes have detected: for small overpotentials the response obeys classical laws of linear diffusion, larger behaviour involves gas coming from bubbles. A model is presented to describe these mechanisms. Four steps are considered: dissolution chlorine around bubble, diffusion electrolyte, charge transfer and chloride ion migration. first step always rapid. influence three other examined. It indicated that largest part occurs near triple contact interface. At very extremity tip, primary limiting factor: it considered over distance few atomic diameters mass transport distances dissolved constitutes main factor. ohmic drop due electrical resistance electrolyte remains small. interfacial tension shape bubbles predicted. non-stationary situation also examined order take into account size variation during conditions.