Polydopamine-modified Zn–Al-layered double hydroxide supported silver nanoparticles as recyclable heterogeneous nanocatalyst for reduction of 4-nitrophenol

Abstract

This article introduces the design and synthesis of Ag NP garlanded polydopamine (PDA)-functionalized Zn–Al-layered double hydroxide (Zn-Al LDH@PDA) as a hybrid green nanocomposite material, hitherto unreported. The precursor Zn-Al LDH@PDA acted as a suitable shelter and stabilizing support for the in situ generated Ag NPs. The electron rich amino functions over the PDA facilitated the toxic reagent free green reduction of Ag ions in situ. A diverse range of advanced methods, including Fourier Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDX), elemental mapping, Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HR-TEM), Fast Fourier Transform (FFT), Inductively Coupled Plasma (ICP), N2 adsorption–desorption, and X-ray Diffraction (XRD) were employed to analyze the physicochemical features of the Zn-Al LDH@PDA/Ag nanomaterial. Catalytic performance of the Zn-Al LDH@PDA/Ag nanocomposite was subsequently appraised in the reduction of 4-nitrophenol (4-NP). The reactions were evaluated through time dependent UV–Vis spectroscopic study which proved the excellent potential of the catalyst. The Zn-Al LDH@PDA/Ag NPs nanocatalyst was isolated by centrifuge and stable enough to be reused for 8 consecutive times without considerable loss in activity.

Keywords

• Layered Double Hydroxide (LDH)
• Silver
• Polydopamine
• 4-Nitrophenol