Temperature-Dependent Electrosynthesis of C2 Oxygenates from Oxalic Acid Using Gallium Tin Oxides

The electrosynthesis of multi-carbon chemicals such as glyoxylic acid (GX) and glycolic acid (GC) from oxalic acid (OA) offers a feasible pathway to achieve sustainable chemical production, especially when coupled with the electroreduction of CO2 to form OA. Here, we demonstrate a series of gallium tin oxide catalysts for selective, controlled OA electroreduction to GX and GC in acidic media. The product distribution can be tuned by changing the reaction temperatures. At room temperature using the GaSnOx/C catalyst, GX can be obtained with a GX Faradaic efficiency (FEGX) of 92.7% at −0.7 V vs RHE and a GX current density (jGX) of −100.2 mA cm–2. At a raised temperature of 80 °C using the GaSnOx/C catalyst, a GC Faradaic efficiency (FEGC) of 91.7% at −0.8 V vs RHE can be obtained. The accelerated OA electroreduction results from the Ga/Sn synergy in the catalysts. A proper Ga/Sn ratio not only enriches OA adsorption and enhances surface binding of intermediates, but also ensures catalyst stability in acidic media.