Organic Ligand-Enhanced Covalent Fe Coordination in NiFe LDH for Efficient Biomass Upgrading

Electrocatalytic conversion of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) presents a promising route for the bio-renewable polymer industry. However, the development of efficient catalysts remains a key challenge. Herein, a NiFe layered double hydroxide (LDH) catalyst modified with an organic carboxylate ligand, trimellitic acid (TA) (denoted as NiFe LDH-TA) is designed. This catalyst exhibits impressive performance in HMF oxidation, achieving an impressive FDCA yield of 97.5% while maintaining stable operation for 200 h. X-ray absorption spectroscopy and theoretical analysis reveal that the introduction of TA enhances the interaction between NiFe LDH and HMF, effectively facilitating efficient proton-coupled electron transfer and boosting catalytic activity. Furthermore, the covalent coordination between Fe and O in NiFe LDH-TA is strengthened as the number of carboxylate ligands increases. This reinforcement, attributed to the formation of robust Fe─O─C bonds, prevents its excessive oxidation and dissolution. This dual enhancement strategy, which simultaneously optimizes activity and durability, offers a promising avenue for efficient biomass upgrading.