Electrosynthesis of Biodegradable Polymer Monomers of Glycolic Acid from CO ₂

Glycolic acid (C2H4O3) is one of the important monomers for producing biodegradable plastics. Traditional methods for the synthesis of C2H4O3 have long been confronted with high cost and unsustainable issues. Compared with traditional methods, the electrosynthesis of C2H4O3 from CO2 serves as a clean and environmentally friendly alternative. Herein, we developed a two-step cascade method for the electrochemical synthesis of C2H4O3 from CO2. By innovative design of a membrane-free flow electrolytic device, we reduced the overpotential of the CO2 to oxalic acid (C2H2O4) process. Subsequently, Bi nanosheets (NS) were exploited to boost the activity and selectivity of C2H4O3 towards C2H2O4 electroreduction. A kinetic study indicated that increasing temperature accelerated the electroreduction process of the desorbable glyoxylic acid (C2H2O3). Under the optimized reaction conditions, the partial current density of −128.8 mA cm−2 was achieved for the production of C2H4O3. Meanwhile, selectivity for C2H4O3 higher than 72.7% could be maintained during the 96 h cyclic stability test. A mechanistic study revealed that Bi NS with both a moderate intrinsic activity for proton activation and a moderate adsorption for C2H2O3 enabled the high performance for the electrosynthesis of C2H4O3.