CUR - The Council on Undergraduate Research

Elucidating the Reaction Mechanism of HMF Electrooxidation to FDCA via Kinetic Studies on Shape-Controlled Platinum Nanocatalysts

Nina Hooper, Taylor Spivey, Todd Whittaker, and Dr. Adam Holewinski, Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, CO 80309

Upgrading biomass-derived compounds to industrially important compounds provides a sustainable alternative to sourcing those compounds from fossil resources. 5-hydroxymethylfurfural (HMF) is an important biomass derivative that can serve as a platform chemical for the production of an abundance of valuable materials. We are particularly interested in the selective electrooxidation of HMF to 2,5-furandicarboxylic acid (FDCA), an important molecule in the production of sustainable plastics. The kinetics of the electrooxidation of HMF to FDCA is examined via liquid product analysis in a custom-designed batch electrolysis cell, with well-defined shape-controlled platinum nanocrystals acting as catalysts. Polycrystalline platinum catalysts have been shown to increase selectivity toward FDCA as compared to other metals such as gold; however, the catalyst shape-dependence has largely been unstudied. Cubic and octahedral nanoparticles, exhibiting {100} and {111} crystal facets, respectively, are used in order to elucidate the structural dependence of the reaction mechanism on Pt metal. The nanoparticles are synthesized via a size tunable colloidal method, verified by high resolution transmission electron microscopy, and examined under electrooxidation conditions. The dependence of the FDCA yield and formation rate on the presence of {111} versus {100} facets, as well as on the relative density of edge sites, is used to gain insight into the operating surface mechanism controlling the reaction. These results build collective understanding of the surface behavior and tunability of the HMF electrooxidation reaction and inform the design of better nanoparticle catalysts for biomass refining.

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