Direct Power Charge and Discharge Using the Glycolic Acid/Oxalic Acid Redox Couple toward Carbon-Neutral Energy Circulation

Abstract

We demonstrated an electric power circulation method that does not emit CO 2 and is based on the glycolic acid (GC)/oxalic acid (OX) redox couple. Electric power charge in GC was achieved through OX electro-reduction with high selectivity (>98%) using purely anatase-type TiO 2 spheres in the potential region of -0.5 to -0.7 V vs. RHE at 50 ºC. We also realized GC production via the combination of electrochemical OX reduction and electrooxidation of water with the help of renewable light energy for the first time. Furthermore, we succeeded in power generation via the selective electro-oxidation of GC to OX without CO 2 emission. These results are the first experimental proof of the carbon-neutral power circulation involving an alcohol/carboxylic acid redox couple.