In situ immobilized palladium nanoparticles (Pd NPs) on fritillaria imperialis flower extract-modified graphene and their catalytic activity for reduction of 4-nitrophenol

Abstract

Abstract In this study, a complete green synthesis method to reduced graphene oxide-Pd nanoparticles hybrid by applying extract of Fritillaria imperialis flower as both stabilizing and reducing agent was reported. Fritillaria imperialis flower extract reduce graphene oxide and adsorb on the reduced graphene oxide surface. Moreover, the surface adsorbed Fritillaria imperialis flower extract can more in situ reduce Pd ions to Pd nanoparticles and stabilize them. The physicochemical and structure properties of the produced nanohybrid were examined in detail by X-ray diffraction (XRD), UV–vis spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), wavelength-dispersive X-ray spectroscopy (WDX), inductively coupled plasma (ICP) and X-ray photoelectron spectroscopy (XPS). The obtained results showed that Pd nanoparticles uniformly distributed on the functionalized graphene surface. The catalytic efficiency of the resulting heterogeneous nanocatalyst (Pd NPs/FGO) was evaluated at room temperature for the 4-nitrophenol (4-NP) reduction in an environmental friendly medium. The enhanced catalytic activity observed with our nanocatalyst is attributed to the graphene surface's coated by biopolymers of Fritillaria imperialis flower extract which stabilizes and attracting the aryl nitro substrates adjacent to the catalytic sites which in turn facilitates the reduction of nitro groups. The catalyst was recycled by centrifugation and reapplied several times without any significant catalytic activity loss.