Enhanced Electrocatalytic Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid via N-Hydroxyphthalimide-Integrated Porphyrin(Co) Covalent Organic Frameworks

Abstract

The depletion of fossil fuel reserves, coupled with the mounting environmental concerns, highlights the urgent need to develop sustainable methods for chemical synthesis from renewable resources. One promising avenue is the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), utilizing non-precious metal catalysts. Herein, we designed and synthesized covalent organic frameworks (COFs) as electrocatalysts, engineered through the integration of N-hydroxyphthalimide (NHPI) linkers with porphyrin building blocks. Electrochemical studies revealed that the Co-Por-COF-NHPI with metallic porphyrin(Co) surpassed the nonmetallic Por-COF-NHPI in conversion, selectivity, and recyclable stability by virtue of the lower onset potentials, higher current densities, and diminished charge transfer resistance. The Co-Por-COF-NHPI achieved remarkable HMF conversion of 95.5% and selectivity to FDCA of 95.6%, attributable to the synergistic effect of porphyrin(Co) and oxidative organocatalytic NHPI sites. Continuous cycling tests further verified its outstanding stability and durability, underscoring the potential of Co-Por-COF-NHPI as an efficient and sustainable catalyst for biomass conversion.