In Situ Investigation of d-Glucose Oxidation into Value-Added Products on Au, Pt, and Pd under Alkaline Conditions: A Comparative Study

The mechanisms of oxidation of glucose, gluconic acid, and sorbitol have been studied on gold, platinum, and palladium using cyclic voltammetry (CV), differential electrochemical mass spectrometry (DEMS), and in situ Fourier transform infrared (FTIR) spectroscopy. The nature of the reactant has a strong impact on the onset of the oxidation reaction. The anomeric function of glucose is oxidized at low potentials on the three surfaces, while gluconic acid and sorbitol poison the surface at low potentials. In addition, the nature of the metal surface leads to different reaction pathways. It is proposed that the oxidation of glucose initiates via the partial dissociative adsorption of glucose into glucose adsorbates and adsorbed H (Had) for the three metal surfaces. These adsorbates are partially combined into H2 on Au and oxidized into water on Pt and Pd. In addition, Au features the best activity, selectivity, and specificity for glucose oxidation into gluconate at low potentials. The study points out a reactant, catalyst, and potential dependent mechanism.