Electrocatalytic oxidation of monosaccharides on platinum electrodes modified by thallium adatoms in carbonate buffered medium

Bioelectrochemical synthesis of gluconate by glucose oxidase immobilized in a ferrocene based redox hydrogel

The integration of redox enzymes on electrode surfaces enables the use of renewable energy for highly specific bioelectrochemical synthesis. Herein, we investigate the oxidation of glucose to gluconic acid on a bioanode, combining electrochemical and enzymatic components. Gluconic acid is a valuable chemical widely used in the industry. The bioanode consists of a redox hydrogel film of polyethylenimine (PEI) containing ferrocene (Fc) as a mediator, glycerol diglycidyl ether (GDGE) as a cross-linker, and the enzyme glucose oxidase (GOx). Optimization of the enzyme and cross-linker loading in the redox film led to faradaic efficiencies up to 96 ± 5 % for gluconate. The oxygen-free setup was highly stable for quantitative electrosynthesis, yielding gluconate concentrations of 6.4 ± 0.25 mmol L^-1. Moreover, this catalase-free anaerobic system showed no production of H₂O₂ within 24 h, thereby eliminating the deactivation of the GOx caused by H₂O₂ and a high enzyme performance, with a turnover frequency (TOF) of 5 x10^-3 s^-1. This is the first quantitative bioelectrosynthesis of gluconate in an entirely anaerobic environment with electrode stability of at least 8 h.

Electrosynthesis of Biobased Chemicals Using Carbohydrates as a Feedstock

The current climate awareness coupled with increased focus on renewable energy and biobased chemicals have led to an increased demand for such biomass derived products. Electrosynthesis is a relatively new approach that allows a shift from conventional fossil-based chemistry towards a new model of a real sustainable chemistry that allows to use the excess renewable electricity to convert biobased feedstock into base and commodity chemicals. The electrosynthesis approach is expected to increase the production efficiency and minimize negative health for the workers and environmental impact all along the value chain. In this review, we discuss the various electrosynthesis approaches that have been applied on carbohydrate biomass specifically to produce valuable chemicals. The studies on the electro-oxidation of saccharides have mostly targeted the oxidation of the primary alcohol groups to form the corresponding uronic acids, with Au or TEMPO as the active electrocatalysts. The investigations on electroreduction of saccharides focused on the reduction of the aldehyde groups to the corresponding alcohols, using a variety of metal electrodes. Both oxidation and reduction pathways are elaborated here with most recent examples. Further recommendations have been made about the research needs, choice of electrocatalyst and electrolyte as well as upscaling the technology.

Recent advances in the electrooxidation of biomass-based organic molecules for energy, chemicals and hydrogen production

The recent developments in biomass-derivative fuelled electrochemical converters for electricity or hydrogen production together with chemical electrosynthesis have been reviewed.