## The initial kinetics of glycerol conversion was calculated

The initial kinetics of glycerol conversion was calculated using a macro-kinetics model based upon the first-order rate [56]. The data fitted very well with the first-order kinetics model over the first 5, 12 and 4 h for the Pt grid, Ti/RuO2 and SS cathodes, respectively, with a coefficient of determination (R2) of greater than 0.988 in all three cases (Insert of Fig. 5). From this linear part of the plot, the glycerol solution at an initial Caspase-3/7 Inhibitor of 1 gave a rate constant (k) of 1.19 × 10−3, 4.13 × 10−4 and 5.54 × 10−4 min−1 for the Pt grid, Ti/RuO2 and SS cathodes, respectively.

The Faradaic current efficiency (?F) of each cathode was then calculated from Eq. (4) [56];equation(4)?F=QthQexp×100where Qth is the theoretical quantity of electricity calculated from the detected reaction products and Qexp is the experimental quantity of electricity measured by the coulometer. The term Qth is derived as shown in Eq. (5);equation(5)Qth=nFVΔCQth=nFVΔCwhere n is the theoretical number of Faraday for the oxidation of glycerol in product (i), F is the Faraday's constant, V is the volume of the reaction mixture and ΔC is the concentration of the transformed glycerol.