Metal sulfide enhanced metal-organic framework nanoarrays for electrocatalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid

Electrochemical oxidation of 5-hydroxymethylfurfural (HMF) is an efficient and sustainable way to produce a 2,5-furandicarboxylic acid (FDCA) monomer. In this study, two-dimensional (2D) metal-organic framework (MOF) nanoarrays embedded with Ni/Co/Fe sulfide nanoclusters were employed as electrocatalysts for HMF oxidation. The as-prepared NiCoFeS-MOF catalyst had interlaced structures and achieved 100% HMF conversion, 99% FDCA yields and Faraday efficiencies as high as 99% at 1.39 V vs. RHE driving voltage. Combination of metal sulfide nanoclusters with 2D MOF nanoarrays greatly enlarged the electrochemical active surface area and increased the number of active catalytic sites while improving electron transport. X-ray photoelectron spectroscopy indicated that electronic interactions increased the electron density of metal sites and enhanced intrinsic NiCoFeS-MOF electrooxidation performance. Embedding metal sulfide nanoclusters into MOF nanoarrays using the simple one-step solvothermal method proposed in this work greatly expands the scope of electrode materials available for electrochemical upgrading of biomass-related compounds.