Simultaneous Electrochemical Oxidation of Methylene Blue and Reduction of CO2 using CNTs/CF Electrodes

Abstract

Simultaneous degradation of methylene blue (MB) and reduction of CO2 by electrochemical process using CNTs/CF electrodes have been performed in various supporting electrolytes and applied current conditions in this study. The CNTs/CF electrodes have been successfully synthesized by chemical vapor deposition (CVD) method and employed as both cathode and anode in a two-compartment electrochemical cell. The synthesized electrodes were characterized by SEM and FTIR. The electrochemical oxidation efficiency of CNTs/CF electrodes in the anodic cell was evaluated using MB as model compound under electrolytes of H2SO4 and KHCO3 and applied currents of 10, 50 and 100 mA. The electrochemical reduction activity of CNTs/CF electrodes in the cathodic cell was assessed by the conversion of CO2 into CO and oxalic acid, and the generation of H2 under electrolytes of Na2SO4 and KHCO3 and a fixed applied current of 50 mA. The degradation kinetics of MB followed the pseudo-first-order model and the degradation efficiency was significantly affected by applied current rather than the sort of electrolyte under optimum condition. The optimal applied current can promote the high enough production of oxidant but also avoid electrode damage. The synthesized electrode of CNTs/CF combined with the electrochemical systems developed in this study provide a good solution for the simultaneous electrochemical oxidation of organic pollutants and reduction of CO2 to CO to yield H2 and CO, in which reaches the dual benefits of reduction of environmental hazards and production of green energy.