A versatile single-copper-atom electrocatalyst for biomass valorization

Single atom electrocatalysts (SAECs) exhibit intriguing catalytic performance due to their utmost atom-utilization efficiency and unique electronic structure. However, the application of SAECs is limited on simple reactions such as the hydrogen/oxygen evolution reactions, and oxygen/nitrogen reduction reactions. Herein, single copper atoms supported on nitrogen doped carbon nanosheets (Cu/NCNSs) were demonstrated as a versatile SAEC for biomass upgrade. The activity of Cu/NCNSs was benchmarked against commercial Cu nanoparticles. Twelve basic platform compounds including 5-hydroxymethylfurfural (HMF), furfural, glucose, formaldehyde, methanol, ethanol, isopropanol, ethylene glycol, glycerol, benzyl alcohol, formic acid, and oxalic acid were employed as substrates. The products of electro-oxidation of these substrates were analyzed by high performance liquid chromatography. The reaction pathways and mechanisms of substrate oxidation on Cu/NCNSs and Cu NPs were explored by in-situ electrochemical Raman spectra. HMF oxidation on Cu NPs followed the 5-diformylfuran (DFF) path at lower potentials, while it turned to 5-hydroxymethyl-2-furancarboxylic acid path at applied potentials over 1.67 V. For Cu/NCNSs, HMF oxidation followed the alcohol hydroxyl oxidation pathway, that is, the direction of generating DFF. The active sites for substrate oxidation on Cu/NCNSs are different from those on Cu NPs. This work broadened the application of SAECs in the field of biomass upgrade, and paved a new route to fabricate advanced electrocatalysts for biomass valorization.