Ionic liquids (ILs) are widely used for electrochemical studies. However, electrochemical reactions taking place in ILs could be complicated by the interfacial IL ion layers at the electrode/IL interface. In this work, such complications are revealed via the electrochemical study of indium(III)/indium redox couple in the 1-butyl-1- methylpyrrolidinium dicyanamide ([BMP]+[DCA]-) IL. Anomalous voltammetric behavior is observed with static cyclic voltammetry, convective rotating disk electrode voltammetry, and potential step chronoamperometry. The results indicate that the In(III) reduction process is complicated by the adsorption/desorption of the [BMP]+ cations. Meanwhile, less anomalous voltammetric behavior is observed in the 1-ethyl-3-methylimidazolium dicyanamide ([EMim]+[DCA]-) IL, in agreement with the weaker adsorption strength of the [EMim]+ cation. The impact of the cation adsorption is weakened by raising the temperature.
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