Revisiting the electrocatalytic hydrogenation of furfural to furfuryl alcohol using biomass-derived electrolytes

Abstract

Electrocatalytic hydrogenation of furfural to furfuryl alcohol represents a sustainable approach to utilizing renewable energy for producing bio-based platform chemicals. However, low Faraday efficiencies (FEs) and the use of organic solvents with high environmental impacts often render the process less sustainable than classical catalytic hydrogenation. In this study, we tested a two-compartment and three-electrode setup at ambient temperature and atmospheric pressure, featuring various electrodes (Ag, Au, CP, Cu, Pt, Sn, and a gold-coated silver wire (AucAg)), and biomass-derived electrolytes (acetic acid, levulinic acid, and sodium acetate). AucAg, serving as an electrocatalyst with 1 M sodium acetate as electrolyte, exhibited the best combination of FE and furfuryl alcohol yield with 79% and 35%, respectively. The optimum conditions were achieved at 100 rpm (stirrer speed) and −0.7 V vs. RHE. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyzes indicated no significant influence of the substances on the working electrode during the reaction. Since the identity of the cation of the electrolyte influences the electrode–electrolyte microenvironment, multiple alkali metals were trialed. Sodium ion as the counter ion emerged on top, surpassing potassium, and cesium ions for the electroreduction of furfural to furfuryl alcohol. This preference could be attributed to the competing hydrogen evolution reaction favored by Cs over K and Na. In this perspective, the highlights of a bioelectrorefinery concept for creating a bio-derived platform chemical in a sustainable solvent with green electrons are demonstrated and optimized.