(Invited) Highly Active Pt-Modified Catalyst for the Selective Electro-Oxidation of Saccharides

The increasing demand of energy and high value-added compounds, and the extinction of fossil resource reservoirs result in replacing fossil resources with biomass. Cellulose and hemicellulose represent 40 to 60 wt% of agriculture green wastes and can be considered as raw materials. After transformation of these biopolymers into saccharides, the latter can serve as platform molecules to produce chemicals with high value added and/or industrial interest. In that context carbohydrates need to be studied more deeply for obtaining every possible outcome. Focusing on environmental problems, electro-reforming can provide hydrogen together with a supplementary valuable industrial compound, but this last process must show very high selectivity and low cost to compete with classical biotechnological methods for sugar conversion. monosaccharides, disaccharides and oligosaccharides are complex molecules bearing several oxygenated functions (primary alcohol, secondary alcohol, anomeric group) that are potentially electrochemically reactive. Therefore, it is needed to develop catalysts displaying very high activity at low potentials and very high selectivity towards a given compound. For this purpose, the synthesis and characterization of Pt-based binary catalysts will be presented and their electrocatalytic behavior towards the oxidation of saccharides (glucose and cellobiose bearing a reductive anomeric function, and methylglucoside and trehalose with a protected anomeric function) will be first studied by linear scan voltammetry in a classical three-electrode cell to evaluate their activity and by in situ infrared spectroscopy to determine reaction intermediates and products as a function of the electrode potential. Best candidates will be used as anode catalysts to perform the electroreforming of saccharides in a two-electrode electrolysis cell with simultaneous production of hydrogen at the cathode. Reaction products will be analyzed by HPLC, MS, and 1H and 13C NMR to determine the selectivity and the efficiency of the system. From the electrochemical and analytical results, the high efficiency of the Pt9Bi1/C catalysts will be emphasized, the electro-reactivity of the different functions determined, and reaction mechanisms discussed.