ORMOSIL-entrapped copper complex as electrocatalyst for the heterogeneous de-chlorination of alkyl halides

The development of an efficient method for the de-halogenation of alkyl halides is an essential step towards the elimination of these pollutants from the environment. Here we show that entrapment of an electro-catalyst in sol-gel electrodes yields efficient electrodes for this process. In this study Cu(1,4,8,11-tetra-aza-cyclotetra-decane)²⁺ was used as the active catalyst in the de-chlorination of CCl₃CO₂⁻. The major electro-catalytic product is oxalate while a minor product, depending on experimental conditions, is either glyoxalate or acetate. The efficiency of the electro-catalytic process depends on the nature of the precursors used to prepare the sol-gel matrix. The observed electro-catalytic current decreases when cyclic voltammetry is performed at high scan rates. This surprising result indicates that the mechanism of the electro-catalytic process is dependent on the scan rate. Plausible mechanisms at low and high scan rates are proposed.