Insight into Carbon Hybrid and Interfacial Modulation for High-Performance Electrosynthesis of Ethylene Glycol

Electrocatalytic reduction of formaldehyde with H₂O on a carbon-based catalyst has shown a promising route for ethylene glycol (EG) production; however, most of the corresponding parameters are still unsatisfactory to support industrial applications. In this work, the carbon-electrolyte interfaces by regulating carbon hybrid and introducing quaternary ammonium-based ionic liquids were investigated to improve Faradaic efficiency of EG (FE_EG) with high durability at high current density (j) and low temperature. The nondefective sp²-hybridized carbon (sp²-G) was demonstrated as the main active site leading to EG. Remarkably, a high FE_EG of 92.0% was thus achieved on ND-1400 at −1000 mA cm^-2 with 2 wt % dodecyl trimethylammonium chloride at 50 °C. The performance remained basically unchanged within 40 h of electrolysis at −200 mA cm^-2. Experimental combined theoretical studies demonstrated the formation of EG versus methanol on the sp²-G carbon is slightly disfavored in thermodynamic. However, the FE_EG and the applied potential, at high j, are mainly influenced by the mass transfer of H₂O while exhibiting opposite correlations. The techno-economic assessment suggested this electrosynthesis of EG is profitable at the current density as high as −400 mA cm^-2 using renewable energy-based electricity in southwest China.