Lignin-based Co–Mn dual single-atom catalyst with asymmetric coordination for efficient oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid

2,5-Furandicarboxylic acid (FDCA) is a promising renewable alternative to petroleum-derived terephthalic acid for the production of bio-based polyesters. However, achieving efficient thermocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to FDCA under mild conditions remains challenging. Herein, we report a lignin-derived nitrogen-doped carbon-supported Co–Mn dual single-atom catalyst (CoMn/LNC) prepared by a chelation-pyrolysis method, which achieves a 99.9% FDCA yield with a productivity of 1542.0 μmol FDCA ·g cat −1 ·h −1 at 65 °C using air as the oxidant. Physicochemical characterizations indicate that an asymmetric CoN 3 –MnN 3 electronic configuration in CoMn/LNC serves as the key catalytic center, which lowers the reaction activation energy and promotes the formation of FDCA under mild condition. Combined density functional theory calculations and in situ DRIFTS reveal that the asymmetric coordination modulates the d-band center, enhances interfacial electron transfer, and promotes HMF adsorption and subsequent oxidation. Furthermore, the asymmetric configuration facilitates oxygen activation and shifts the rate-determining step from the oxidation of HMFCA to FFCA toward FDCA desorption. This work provides a feasible strategy for designing transition metal dual single-atom catalysts for HMF oxidation to FDCA.