Tuning interfacial *H coverage and aldehyde adsorption configuration for selective electrocatalytic hydrogenation of furfural

Abstract

Electrocatalytic hydrogenation (ECH) of furfural (FF) to 2-methylfuran (2-MF) and furfuryl alcohol (FA) is regarded as a sustainable method for upgrading biomass-derived feedstocks into valuable chemicals. It is challenging to simultaneously control both *H coverage and FF adsorption behaviors to understand interfacial structure–activity relationship and achieve a selective target product. Herein, we report the optimization of interfacial proton availability and surface electronic interaction with FF for selective FF ECH in a single system. In the reaction microenvironment, the *H coverage on Pd catalyst was tailored to achieve 2-MF and FA formation at low and high pH levels, respectively. On the electronic structure-tuned surface, the Lewis acid Cu-rich Pd electrodes prefer to interact with oxygen coordination (η-(O)), while Cu-poor Pd electrodes induce the carbon coordination (η-(C)) of FF configuration. In situ spectroscopy reveals that the initial hydrogenation step on adsorbed C or O atoms preferentially forms R–CH2–O˙ or R–C˙–OH radical intermediates, respectively, resulting in selective production of 2-MF on Pd-rich electrodes and FA on Cu-rich electrodes.