Electrocatalytic Hydrogenation of Furfural with Improved Activity and Selectivity at the Surface of Structured Copper Electrodes

Furfural is a pivotal renewable platform molecule obtained from the chemical breakdown of hemicellulose. While it has traditionally been valorized to value-added chemicals through catalytic hydrogenation in biorefineries, its direct electrocatalytic hydrogenation presents attractive advantages. This article describes the significant improvements brought by the structuring of copper cathodes applied to this process in terms of activity and selectivity. We show that structured electrodes are capable of converting furfural to furfuryl alcohol with 100% selectivity at potentials as high as -0.2 V vs the reversible hydrogen electrode (RHE) in neutral conditions (pH 7.0). Moreover, the same electrode can selectively generate either furfuryl alcohol or 2-methylfuran in acidic conditions (pH 1.0), depending on the applied potential and temperature. We further show the existence of optimal voltage-temperature conditions for the efficient conversion of furfural to furfuryl alcohol or 2-methylfuran, highlighting the delicate influence of operating conditions on the selectivity of furfural reduction, in competition with the hydrogen evolution reaction in aqueous electrolytes. These performances are attributed to the resilience of Cu(I) species under operating conditions and their likely contribution to the electrocatalytic active site, as revealed by quasi-in situ photoelectron spectroscopy.