Materials and methods Materials Table Table Preparation of DESs

High purity graphite HPOB (6 mm diameter, 99.999%, Sigma–Aldrich) were used as anodes. In a typical experiment, about 4 cm of the anode was submerged in the solution along with a platinum wire as the counter-electrode (1.6 mm diameter and 4 cm effective length, Goodfellow). As electrolytes, two kinds of ILs (BMiMBF4 and BMPyrrBTA – 99% purity for each IL, Sigma–Aldrich) and acetonitrile (99.9% pure anhydrous, Sigma–Aldrich) solutions were employed mainly for control experiments. In addition to that, a newly proposed solution of DES (either Type I, Type II, Type III or Type IV), IL (BMPyrrBTA) and ACN mixtures were tested (30 ml total volume in each trial) at a constant voltage of 7 V (TTi-EL302R DC power supply with a maximum rating of 30 V and 2 A) at room temperature (293 K). All materials for preparing the DESs (the molar ratios for preparing the DESs are acetyl CoA given in Table 1 while some of their physicochemical properties are shown in Table 2) and the ILs were sourced from Sigma–Aldrich and used as-received.