Tuning Product Selectivity during Electrocatalytic Hydrogenation of Biomass-Derived Furfural through Oxygen Vacancy Control in Metal Oxides

Abstract

Electrochemical hydrogenation (ECH) of biomass-derived compounds is one of the clean routes to produce biofuels. Here, we studied the less-explored technique of ECH of biomass-derived furfural in alkaline medium using metal oxide (In2O3, Co3O4, and Pb2Ru2O7-x) electrocatalysts to generate furfuryl alcohol (FA) and hydrofuroin (HF). The FA selectivity over HF (S-FA/HF) was found to be maximum for P '-Pb2Ru2O7-x, whose FA formation rate (R-FA) (201.3 +/- 5.6 mu mol h(-1) cm(-2), 154.9 +/- 5.8 mmol h(-1) g(cat)(-1)) in the ambient condition (25 degrees C, 0.1 MPa) was higher than the R-FA obtained via thermal catalytic hydrogenation (100-180 degrees C, 1-3 MPa). Through experimental and theoretical studies, we demonstrated that the binding energy and coverage of competing furfural and hydrogen adsorption processes determined the S-FA/HF. Oxygen vacancy formation on the metal oxide surface promoted hydrogen adsorption, resulting in a maximum of S-FA/HF followed by a decrease due to the parasitic hydrogen evolution reaction. The study paves the way for the development of bioelectro-refineries.