(63a) Electroconversion of Biomass-Derived Polyols By Voltage Cycling

Developing novel approaches to using electricity to harness biomass-derived compounds can facilitate the penetration of renewables to the biomass sector whose related advances have been limited compared to other areas involving small molecules. Of the many candidate substrates that exist in nature, C5-C6 polyols derived from lignocellulosic biomass are most suitable as platform molecules due to their large abundance and high functionality. With a lack of basic understanding behind their electrochemistry, it is imperative to study the fundamental electrochemical interactions of these polyols to heterogeneous surfaces and find innovative ways for their utilization. Here, platinum nanoparticles are used as a model system to investigate the basic interactions of C6 sorbitol to their surfaces and explore its potential electroconversion pathways in acidic media. In addition, we present a way to significantly enhance the activity of Pt as catalysts and shift its selectivity that otherwise would not be possible by a simple modulation of electrochemical potentials. First of all, we find that there is a strong potential dependent trend of its dissociative adsorption to form adsorbed carbonyls, both in terms of the rate and equilibrium coverage. Outside that potential range, Pt nanoparticles majorly produce aldoses that are the primary alcohol oxidation products. Moreover, in stark contrast to the catalytic behaviors observed in steady-state conditions, the applied bias constantly modulated in a selected manner enables the Pt NPs to exhibit catalytic turnover that is more than an order of magnitude enhanced and selectivity that shifts towards ketoses (i.e., secondary alcohol oxidation products). These understandings have been translated to a two-electrode device to demonstrate rapid electroconversion of biomass-derived polyols with co-production of H₂. The work not only illustrates the fundamental electrochemical properties of biomass-derived polyols but explores novel methods to facilitate their electroconversion.