Oscillations in the Electro-Oxidation of Thiourea on Platinum Electrode Studied by On-Line HPLC

The oscillations in the electro-oxidation of thiourea on platinum electrode in perchloric acid were studied by the cyclic voltammetry and potentiostatic method combined with on-line HPLC. The effects of different scanning speed, initial concentration of thiourea and sampling on the current oscillations of thiourea were investigated, results showed that: (1) the lower scanning speed and higher initial concentration of thiourea facilitated the oscillations; (2) the sampling increased the oscillation current and oxidation peak current; (3) the intermediates formamidine disulphide (TU22+) and formamidine sulphinic acid (TUO2) were detected at different potentials on the surface of platinum electrode and concentration of TU, TU22+ and TUO2 all exhibited oscillations in the potentiostatic eletrolysis. The existence of a closed feedback loop formed by a series of reactions leaded to electrochemical oscillations of thiourea. This paper provides a new perspective and method for the study of electrochemical oscillations. (C) 2019 The Electrochemical Society.