One-pot green synthesis of gold nanoparticles and its supportive role in surface activation of non-woven fibers as heterogeneous catalyst

Development of eco-friendly and sustainable approaches for the synthesis of metallic nanoparticles are elucidating extensive research in the emerging interdisciplinary field of nanotechnology. Herein, we demonstrate a complete green chemistry and atom-economy route for the rapid production of noble metal-based nanoparticles by utilizing an aqueous extract solution of Chinese native Osmanthus fragrans leaves as reducing and capping agent, irradiated by natural sunlight. Success in the generation of gold nanoparticles (AuNPs) was initially monitored by optical absorption spectroscopy showing the surface plasma resonance (SPR) band around ca. 545 nm range. The size and morphology of AuNPs were controlled and systematically characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), and atomic force microscopy (AFM). Furthermore, the composition of the gold element was assured by energy dispersive X-ray spectroscopy (EDS). The crystallinity state and purity of AuNPs specimen was demonstrated by X-ray diffraction examination. Studying the infrared spectroscopy (FT-IR) revealed the presence of biomolecules on the surface of particles that are responsible for the reduction and stabilization process. Moreover, by adopting the metal-polymer hybrid synthetic approach for surface activation, in situ reduction of AuNPs on non-woven cellulosic fibers acted as support and facilitated catalytic reduction of p-nitrophenol to p-aminophenol via hydrogenation reaction in the presence of NaBH4. The micro-nanocomposite fibers are found advantageous in quick and energy-free recovery and stayed stable for numerous cycles. Overall, exclusion of toxic chemicals by the inclusion of plant extract as reducing agent and photo-energy as a driving force for the generation of AuNPs in aqueous medium makes this process eco-friendly, sustainable and economically viable for large-scale production.