Despite the ability of aqueous-phase electrocatalytic reduction (hydrogenation) to produce fuels,¹ pharmaceuticals, food and other commodity chemicals, the mechanisms of the metal-catalyzed reactions are not always well-understood. Understanding these reactions would allow us to develop improved electrocatalysts and processes to enable sustainable production of important fuels and chemicals. One major challenge in understanding the surface electrochemistry is that the characterization of the electrocatalyst surface is difficult in the presence of water. There are several techniques that can be used to understand the reactant coverages (under reacting conditions), and in this talk a brief overview will be given of spectroscopic techniques (including infrared, Raman, X-ray absorption) and cyclic voltammetry as ways to probe the electrocatalyst surface. In this talk, phenol and benzaldehyde hydrogenation (to cyclohexanol and benzyl alcohol, respectively) on Pt/C and Pd/C will be analyzed using i) experimental and theoretical X-ray absorption spectroscopy and ii) cyclic voltammetry to understand reactant coverages and explain observed reaction rates. Understanding these two models reactants will lead to improved electrocatalysis for not only phenol and benzaldehyde, but also similar compounds that exist in in waste bio-oil, which can be converted to transportation fuel-grade hydrocarbons. The effect of applied potential, reactant and product concentration, and pH on both electrocatalyst surface (including adsorbates) and reaction rate will be discussed. A brief discussion of these results with respect to gas-phase hydrogenation will also be included.

References

(1) Song, Y.; Gutiérrez, O. Y.; Herranz, J.; Lercher, J. A. Appl. Catal. B Environ. 2016, 182, 236.