Efficient electrooxidation of 5-hydroxymethylfurfural enabled by Au-promoted Co3O4 needle-shaped arrays

● Au particles were in situ grown on spinel Co 3 O 4 needle-shaped arrays. ● Au induced Co–O lattice distortion, Co vacancies and Co 3 O 4 low-potential reconstruction. ● Au-driven charge redistribution shifted Co 3 d states toward E f and accelerated charge transfer. ● CoOOH active sites enhanced C O adsorption and facilitated HMFCA-to-FFCA oxidation. ● Au-Co 3 O 4 enabled 99.5% FDCA yield and 99.7% FE and rivalled the top Co-based catalysts. 5-Hydroxymethylfurfural electrooxidation (HMFOR) into 2,5-furandicarboxylic acid (FDCA) is a very promising route for biomass upgrading. Although Co 3 O 4 catalyst is favored due to superior redox ability and high activity, it still suffers from harsh reconstruction of Co–O units and sluggish cascade oxidation of intermediates. Here, low-loading Au was discovered to provoke Co 3 O 4 catalytic properties for efficient HMFOR in the alkaline media. The developed Au-Co 3 O 4 catalyst showed a low onset potential at 1.18 V ( vs. reversible hydrogen electrode, RHE) and delivered a current density of 100 mA cm –2 at only 1.34 V in 1 M KOH, outperforming the top Co-based catalysts reported to date in the literature. Au particles in strong interaction with Co 3 O 4 needle-like arrays induced the lattice expansion and anisotropic distortion of octahedral Co 3+ –O units, cobalt-vacancy defects, and surface electronic redistribution of Co 3 O 4 . As a result, these unique properties of Au-Co 3 O 4 enabled enhanced interfacial charge transfer, stronger adsorption of furanic reactants, and substantially accelerated HMFOR kinetics compared with Co 3 O 4 and Au electrodes. It was disclosed that Au-provoked structural and electronic perturbations of Co–O units allowed low-potential reconstruction to CoOOH active sites and promoted formation of OH-derived oxidizing agents under the mild operating potentials. These coupled effects can account for the improved intermediate selective oxidation into FDCA. 99.5% yield of FDCA with 99.7% Faradaic efficiency at 1.36 V was accordingly achieved. To the best of our knowledge, this work can be the first example of success in Au-regulated Co 3 O 4 electrocatalysis for steering selective oxidation of biomass derivatives. Download: Download high-res image (181KB) Download: Download full-size image