Electrification of glucose valorization over NiO/Ni foam

Abstract

The selective electrochemical oxidation of biomass compounds is a promising route to reduce the carbon footprint in the chemical industry. The process avoids the use of strong chemical oxidants or high oxygen pressures and can be powered by renewable energy; however, these key advantages are only significant when coupled with the selective production of the desired reaction product, a challenging task for highly reactive biomass derived compounds. Glucose oxidation over Ni electrocatalysts has been widely studied for diabetes sensors and fuel cells, while the product distribution under conditions suitable for its valorization into gluconic (or glucaric) acid is barely investigated. Herein, a careful study on the influence of the electrochemical and chemical reaction parameters on the glucose electro-oxidation product distribution is performed (i.e., potential applied, reaction time or accumulated charge, glucose concentration, reactivity of fructose and gluconic acid). The glucose oxidation over single Ni catalysts follows a complex pathway; the activation of the aldehyde and alcohol in C1 and C6, respectively, are possible, but the selectivity to gluconic and glucaric acids is hampered due to over-oxidations, retroaldol and isomerization reactions.