Mechanism and kinetics of the electrocatalytic hydrogenation of furfural to furfuryl alcohol

The side reactions for the electrocatalytic hydrogenation of furfural are related to the type of catalyst. This paper reports the mechanism including the reaction process and rate determining step of the hydrogen evolution reaction (HER) at seven kinds of electrodes (Cu, Pb, Ni, Fe, Pt, Ti, Graphite) in 0.1 M Na2CO3-NaHCO3 buffer solution (pH = 10). The sequences of exchange current density and overpotential for the HER at different electrodes were determined. In particular, the mechanism and kinetics of the electrocatalytic hydrogenation of furfural at those electrodes were analyzed by cathodic linear sweep voltammetry in the presence of furfural. Current efficiency and selectivity were obtained by potentiostatic electrolysis. It shows that the optimal electrode for the reduction of furfural is Cu electrode. The HER at Cu electrode is only a bit easier than that at Pb electrode. However, the generation of carbon free radicals at Cu electrode is the easiest, and the selectivity towards the formation of furfuryl alcohol at Cu electrode is the highest among those electrodes. The results offered some guiding significance how to choose the optimal electrocatalyst for the catalytic hydrogenation of furfural.