Electrocatalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid via metal-organic framework-structured hierarchical Co3O4 nanoplate arrays

Electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) was examined as an alternative to thermocatalytic methods in which two-dimensional (2D) cobalt-metal–organic framework (Co-MOF, ZIF-L-Co) nanoplate arrays were prepared on nickel foam (NF) and then transformed into hierarchical porous Co 3 O 4 nanostructures by chemical etching and low temperature annealing to form electrode materials . Hierarchical porous nanoarrays formed during synthesis enlarged the surface area of the as-prepared catalysts introduced a large number of defects and exposed active sites leading to reduced charge diffusion , improved mass transfer and efficient HMF oxidation . Co 3 O 4 /NF electrode materials were able to achieve a current density of 10 mA·cm −2 at an overpotential of 105 mV in 1 M KOH with 10 mM HMF, which was reduced by 175 mV compared with water oxidation. Electrocatalytic oxidation experiments afforded 100 % HMF conversion and 96.7 % FDCA yields with a minimum 96.5 % faradaic efficiency at 1.43 V vs RHE. The proposed MOF-structured synthesis method fundamentally reduces charge diffusion , improves mass transfer of electrodes and is generally applicable to fabrication of hierarchical porous nanostructured materials.