Electrochemical reaction mechanism of aqueous polysulfide solution①
(1. Department of Chemical Engineering, Xiangtan Polytechnic University,
Xiangtan 411201, P.R.China;
2. Department of Chemistry, Central South University of Technology,
Changsha 410083, P.R.China)
Xiangtan 411201, P.R.China;
2. Department of Chemistry, Central South University of Technology,
Changsha 410083, P.R.China)
Abstract: Cyclic voltammetry and choronopotentiometry studies on aqueous polysulfide solution at graphite anode have been reported. The experiments show that the anode oxidation of the polysulfide, which consists of several parallel electrode reactions and following chemical reactions, is an irreversible process, and that the potential peak in time potential curves for constant current steps indicates a self-catalysis process in the electrochemical oxidation of the polysulfide solution. It is found from further analysis for the cyclic voltammetry and choronopotentiometry that the number of electrons transferred in rate-determining process of the anode oxidation is close to 1, and that the reaction rate constant of self-catalysis is large. These results indicate that interreactions of the polysulfide are quick processes. The potential peak in the potential time curve disappears with the increase of the current.
Key words: polysulfide; voltammetry; electrolysis