Decoupled Molecular Motifs and Supramolecular Dimers for Highly Efficient FDCA Synthesis from Neutral Biomass.

Abstract

Solar-driven biomass valorization is pivotal for defossilizing the chemical industry. The oxidation of abundant, low-cost 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA)─a key monomer for next-generation bioplastics─is a long-sought goal yet hampered by sluggish kinetics, poor selectivity, and alkaline dependency. Here, spatially decoupled catalytic sites are engineered on two-dimensional carbon nitride (CN): covalently grafted cyanamide (CA) motifs at the edges and π-π stacked J-type nickel phthalocyanine (NiPc) dimers on the planes. This design features spatiotemporally cascaded charge transfer and dual-site catalysis, achieving 54- and 160-fold enhancements in the HMF conversion rate and H2 evolution rate, respectively, versus pristine CN, during HMF reforming in pure water. The FDCA production rate reaches 2.14 mmol g-1 h-1 with 98.2% selectivity, outperforming benchmark systems. Fundamentally, CA motifs steer an ultrafast hole-initiated selective HMF oxidation with a hole transfer rate of 2.4 × 1010 s-1 (an order of magnitude faster than CN). The resulting long-lived electrons are extracted by the bottom-layer NiPc and transferred via its single Ni atom to the top-layer single Ni atom for proton reduction, with an electron transfer rate of 7.4 × 104 s-1. The asymmetric charge kinetics suppresses charge recombination, yielding a charge transfer efficiency of 98.9%.