Protocol for electrocatalytic hydrogenation of 5-hydroxymethylfurfural using H and flow cells.

Recently, there has been a growing interest in using sustainable energy to decrease lignin monomers to generate high-value-added products. Here, we present a protocol for electrocatalytic hydrogenation of 5-hydroxymethylfurfural. We describe steps for catalyst preparation, performing electrocatalytic experiments, high-performance liquid chromatography analysis, and in situ infrared reflection-absorption spectroscopy testing. The synthesized catalyst used in this reaction exhibits enhanced selectivity and Faradaic efficiency in NaClO4 solution. For complete details on the use and execution of this protocol, please refer to Zhang et al.1.

Electrocatalytic valorization of lignocellulose-derived aromatics at industrial-scale current densities.

Electrocatalytic hydrogenation of lignocellulosic bio-oil to value-added chemicals offers an attractive avenue to use the increasing intermittent renewable electricity and biomass-derived feedstocks. However, to date the partial current densities to target products of these reactions are lower than those needed for industrial-scale productivity, which limits its prospects. Here we report a flow-cell system equipped with a Rh diffusion electrode to hydrogenate lignocellulose-derived aromatic monomers, such as furans and lignin monomers, to value-added chemicals. We achieve high faradaic efficiencies up to 64% at industrial-scale current densities of 300-500 mA cm-2, representing high productivities to target products. A screening of electrocatalysts indicates that only by highly-electrolyte-permeable Rh diffusion electrodes are we able to unite current density with faradaic efficiency. We apply in-situ infrared reflection-absorption spectroscopy to investigate the electrode-potential-dependent reaction pathways and intermediates, confirming a wide potential window for efficient electrocatalytic hydrogenation of lignocellulose-derived aromatics to target products.

Selective electrocatalytic hydrogenation of lignocellulose-derived 5-hydroxymethylfurfural with superior productivities.

Recently, valorization of biomass to value-added chemicals has drawn increasing attention due to carbon neutrality and sustainability. 5-Hydroxymethylfurfural is an important lignocellulose-derived biomass molecule. Herein, we have demonstrated the efficient electrocatalytic hydrogenation of 5-hydroxymethylfurfural to value-added 2,5-bis(hydroxymethyl)furan. An optimized electrolyzer with a highly electrolyte-permeable Pd cathode well balanced the selectivity, faradaic efficiency, and productivity. We have achieved high selectivity (97%) and faradaic efficiency (72%) at 50 mA cm-2 current density, and a record high productivity of 0.923 mmol cm-2·h-1 at 100 mA cm-2 current density, ∼2 times advanced compared with the best productivity in prior reports. We applied in situ infrared reflection-absorption spectroscopy to investigate the electrode-potential-dependent reaction pathways and mechanism, confirming that the highly selective hydrogenation of HMF is due to the tilted adsorption geometry through carbonyl group bonding to the surface of electrode. This work offers an opportunity for the sustainable electrocatalytic valorization of renewable lignocellulose-derived biomass with superior productivities approaching industrial level.