Pt x Cu100–x /C Bimetallic Catalyst toward Glycerol Electrooxidation in Alkaline Electrolyte: Tuning the Product Selectivity to Glyceric Acid

Valorization of glycerol through electrocatalytic oxidation is a promising and environmentally friendly method that can utilize renewable electricity inputs. Currently, a key challenge facing the development of glycerol oxidation electrolyzers is the lack of cost-effective catalysts with high activity, stability, and selectivity. In this study, bimetallic Pt x Cu100–x /C catalysts synthesized by a chemical reduction method with various metal ratios are shown to enhance glycerol oxidation reaction performance with the addition of Cu to Pt compared to both Pt/C synthesized by the same methods as well as commercial Pt/C. Among the synthesized catalysts, Pt31Cu69/C was determined as the best-performing, exhibiting the highest Pt-mass normalized current density (5.9 mA μgPt –1), the highest geometrical current density (75.3 mA cm–2), and a low onset potential (∼0.38 V vs RHE). Pt31Cu69/C also achieved a high selectivity to glyceric acid (75%) and C3 products (86%) in an alkaline electrolyte over 10 h of chronoamperometry at 0.6 V vs RHE. Moreover, under these same conditions, Pt31Cu69/C produced 2.5-fold higher amount of glyceric acid in comparison to the synthesized Pt/C catalyst via glycerol electrooxidation. The time and electrode potential-dependent product analysis of glycerol electrooxidation reaction for the Pt31Cu69/C catalyst revealed that the addition of Cu to Pt inhibits C–C bond breaking and leads to an increased selectivity of C3 products. Moreover, a reaction pathway of glycerol electrooxidation was proposed for Pt31Cu69/C, highlighting the possible chemical conversions that occur in the alkaline electrolyte.