Paired electrolysis of 5-(hydroxymethyl)furfural in flow cells with a high-performance oxide-derived silver cathode

Abstract

Electrocatalytic upgrading of biomass-derived feedstocks driven by renewable electricity offers a greener way to reduce the global carbon footprint associated with the production of value-added chemicals. In this respect, a key strategy is the electrocatalytic hydrogenation (ECH) reaction, which is typically paired with the anodic oxygen evolution reaction (OER) with sluggish kinetics, producing O₂ with little value. Here we prepared an oxide-derived Ag (OD-Ag) electrode with high activity and up to 98.2% selectivity for the ECH of 5-(hydroxymethyl)furfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF), and such efficient conversion was achieved in a three-electrode flow cell. The excellent BHMF selectivity was maintained over a broad potential range with long-term operational stability. We then considered the oxidation of HMF to 2,5-furandicarboxylic acid (FDCA) and hydrogen (to water) as more efficient and productive alternatives to the OER. In HMF-to-BHMF paired with 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-mediated HMF-to-FDCA conversion, a markedly reduced cell voltage from ∼7.5 V to ∼2.0 V was observed by transferring the electrolysis from the H-type cell to the flow cell, corresponding to more than four-fold increase in energy efficiency in operation at 10 mA. A combined faradaic efficiency of 163% was obtained for BHMF and FDCA. Alternatively, the anodic hydrogen oxidation reaction on platinum further reduced the cell voltage to only ∼0.85 V at 10 mA. These paired processes show the potential for integration of renewable electricity and carbon for green and economically feasible distributed chemical manufacturing.