Alkaline silver nitrate exhibits versatility in the instant oxidation of furans to bioplastic precursors and its mechanistic insights

Abstract

2-furoic acid (FA) and 2,5-furandicarboxylic acid (FDCA) are considered important precursor molecules to produce bio-based polymeric materials (including polyethylene furanoate, PEF). Here, we report a high FA and to FDCA yields of >90% within 1 min using furfural and 2,5-diformylfuran (DFF), respectively, in an AgNO3-KOH system under room temperature conditions. Mechanistic investigations show that Ag+ and in situ generated Ag2O act as redox mediators and are ultimately converted into metallic silver nanoparticles (Ag NPs), as confirmed by XRD, EDX, HRTEM, and XPS characterizations. The theoretical DFT calculations reveal energetically favourable Ag+ and Ag2O-mediated oxidation pathways, consistent with the experimental observations. The 1H NMR, ESI-MS, and UV-vis spectrophotometric methods further support the proposed mechanism. The recovered Ag NPs were subsequently recycled after regeneration and also integrated with TiO2 to form Ag/TiO2 nanocomposites, which exhibit efficient photocatalytic degradation of methyl orange dye. Overall, this work establishes a silver-mediated redox platform that combines biomass upgrading with environmental remediation in a closed-loop.