Effect of the Supporting Electrolyte on Chloroform Reduction at a Silver Electrode in Aqueous Solutions

Herein, we report, for the first time, a comparative study on the electrocatalytic reduction of chloroform on silver in different aqueous supporting electrolytes. Cyclic voltammetry measurements were performed at a wide range of scan rates and concentrations of CHCl₃ using 0.05 M NaClO₄, NaH₂PO4, and Na₂HPO₄ as supporting electrolytes. We observed that a type of supporting electrolyte anion strongly influences both the potential as well as the current density of the chloroform reduction peak, mainly due to the presence of OH^- in an alkaline Na₂HPO₄ solution, which is a specifically interacting anion. Moreover, the highest sensitivity of the Ag electrode toward CHCl₃ reduction was observed in a neutral NaClO₄ aqueous solution. It was found that the electroreduction of chloroform at the silver surface occurs via a concerted mechanism regardless of the type of the studied supporting electrolyte.