NiFe Oxide Catalysts for Electro-Oxidation of Glucose

A new frontier for the chemical industry is the highly selective transformation, by electrochemistry, of raw materials from biomass into intermediates contributing to the transition from a fossil-based to a bio-based economy. Demonstrating the feasibility of this more sustainable approach is one of the objectives of the EU PERFORM project. To establish this new infrastructure, the focus was pointed on specific investigations of target paired reactions. One of these reactions concerns glucose electro-oxidation to glucaric acid, a first step in the electrochemical synthesis of adipic acid (AA) [1]. Here we report, progress in development of a new 3D NiFe oxide catalysts (NiFeOx/NF), obtained from Nickel foam via hydrothermal synthesis for glucose oxidation [2]. Catalyst characterization has been performed by scanning electron microscopy (SEM), XRD and XPS measurements. The findings highlight the successfully preparation of oxide nanosheets via layered double hydroxide species. The anodic materials were tested in batch for the reaction of D-glucose oxidation. A standard three-electrode setup configuration for the electrochemical testing, and a PGSTAT30 (Metrohm Autolab) potentiostat-galvanostat to apply the desired potential were used, respectively. The cell was equipped with a Pt wire as the counter, a saturated Ag/AgCl electrode as the reference, and the prepared NiFe oxides as the working electrode. Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) measurements were recorded, at room temperature, in different electrolyte solutions (1 M KOH and 0.1 M Na2CO3). The electrooxidation of glucose occurs at a lower potential respect to oxygen evolution reaction (OER), the main undesired side reaction, in both electrolytes, and the best results have been obtained with KOH. The glucose oxidation proceeds at first by the formation of gluconic acid, then its conversion takes place, according to step 2 and 3 in Scheme 1. Scheme 1. Possible pathways for glucose electro-oxidation to glucaric acid. Further analyses by chronoamperometric measurements are ongoing for evaluating glucose conversion and selectivity toward glucaric acid under different applied potentials and glucose concentrations. The ongoing research, demonstrating the feasibility of the electro-synthetic approach, open the way toward a more efficient glucaric acid production, helping to promote the emerging electrification of the chemical industry. The new route inspired to green chemistry, allows both energy saving and biomass valorisation.