Comparison Study of the Electrochemical Behavior of Vanadate in NaOH and KOH Solutions

The redox behavior of vanadate ions at glassy carbon electrode in KOH solutions with concentration ranging from 0.1M to 1M had been studied using cyclic voltammetry method. It is found out that vanadate ions experience similar redox reactions in both NaOH and KOH solutions, which involve a single cathodic reduction and two oxidation reactions in one cyclic sweep. Nearly same currents are obtained under the same reaction conditions in both solutions. However, vanadate ions appear more difficult to be reduced in KOH solutions than in NaOH solutions, and the reduction reaction exhibits higher irreversibility. The reduction potential is influenced by vanadate ions concentration, and is more negative in KOH solutions. The reversibility of reduction reaction is greatly dependent on alkalinity, and the reduction potential obviously decreases with the increase of alkalinity in KOH solutions. However, only a slight decrease was observed in NaOH solution, which may be due to the fact that OH- exhibits higher activity in KOH solutions.