Investigation of different deposition methods for synthesized gold nanoparticles on a South African sugarcane leaves derived silica xerogel support

Value added materials made from agricultural residues are very attractive since they contribute in reducing environmental waste and enhancing economic sustainability. Two deposition methods were investigated where silica xerogel from sugarcane leaves (a waste from sugarcane industry) was used as a support for the synthesized gold nanoparticles. Biogenic silica was refluxed with sodium hydroxide at 80 °C to form sodium silicate solution. The gold nanoparticles were either synthesized in the sodium silicate solution or separately to form silica/Au nanoparticles through a sol-gel method. Ultraviolet (UV)-visible spectroscopy, x-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray fluorescence spectroscopy (XRF), energy dispersive x-ray (EDX) and nitrogen adsorption-desorption were used to characterize the produced Si/Au nanoparticles. The two investigated methods resulted in distinctive deposition of gold nanoparticles on a silica xerogel support and also significantly different textural properties. The produced silica/gold nanoparticles had a Brunauer-Emmett-Teller (BET) surface area of up to 619 m²/g, pore diameter of 8.3 nm and pore volume of 1.28 cm³.g⁻¹. (Figure presented.)