In situ synthesis of environmentally benign montmorillonite supported composites of Au/Ag nanoparticles and their catalytic activity in the reduction of p-nitrophenol

Abstract

In the present work, composites of montmorillonite clay supported silver and gold nanoparticles were synthesized by in situ chemical reduction method and characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), UV-vis spectroscopy and Transmission Electron Microscopy (TEM). The clay–nanoparticle composites were synthesized at two different temperatures (25 °C and 75 °C) where nanoparticle size was found to depend on synthesis temperature. The distribution of the catalytic nanoparticles was uniform in the clay matrix with sizes in the range of 20–45 nm (at 25 °C) and 5–15 nm (at 75 °C), respectively. Catalytic activity of the clay–nanoparticle composites were monitored by UV-visible spectroscopy using p-nitrophenol and NaBH₄ as model reactants. The best catalytic efficiency was observed in the case of silver–clay nanocomposites with a rate constant of 5.6 × 10⁻³ s⁻¹.