Electrochemical reduction of biorenewable platform chemicals is an emerging route for sustainable biofuel and chemicals production [1-3]. However understanding gaps between reaction conditions, underlying mechanisms, and observed product selectivity have limited the rational design of effective, active, and stable electrochemical systems. In this presentation, the mechanisms of electrochemical reduction of furfural, an important biobased platform molecule and model for aldehyde reduction are explored through a combination of voltammetry, bulk electrolysis, thiol-electrode modifications, and kinetic isotope studies. It is demonstrated that two distinct mechanisms are operable on metallic Cu electrodes in acidic electrolytes and lead to different products: (i) electrocatalytic hydrogenation (ECH) for methyl furan (MF) and furfuryl alcohol (FA) production, and (ii) direct electroreduction for dimers production. The contributions of each mechanism to the observed product distribution is clarified by evaluating the requirement for direct chemical interactions with the electrode surface and the role of adsorbed hydrogen. Further analysis reveals that hydrogenation and hydrogenolysis products are generated by parallel ECH pathways. Understanding the underlying mechanisms enables the manipulation of furfural reduction by rationally tuning the electrode potential, electrolyte pH, and furfural concentration to promote selective formation of important biobased polymer precursors and fuels.

References:

1. Xin, L. et al., ChemSusChem 2013, 6, 674–686.

2. Matthiesen, J. E. et al. ACS Sustainable Chem. Eng. 2016, 4, 7098–7109.

3. Suástegui, M.; Matthiesen, J. E.; et al. Angew. Chem. Int. Ed. 2016, 55, 2368–2373.