How do Bi-modified palladium nanoparticles work towards glycerol electrooxidation? An in situ FTIR study
Résumé
Palladium nanoparticles with controlled distributions of sizes and shapes were synthesized and characterized by TEM, HRTEM and voltammetric methods. The surfaces of these nanoparticles were modified by spontaneous adsorption of bismuth. The activity and selectivity towards glycerol electrooxidation reaction were determined by coupling cyclic volatmmetry with in situ infrared spectroscopy. Higher activity were observed on pure Pd nanoparticles presenting extended (100) and/or (111) surface domains (nanocubes and nanooctahedrons, respectively), with Pd nanocubes being the most active. The modification of the surface by spontaneous adsorption of bismuth not only greatly improves the activity of Pd nanocubes but also affects the reaction pathway of glycerol electrooxidation. The study allows a better understanding of the material structure/electrocatalytic behavior relationship, which is essential on a fundamental point of view for the determination of reaction mechanisms and on a practical point of view for the rational design of catalysts active and selective towards oxidation of polyols from biomass