Rapid hydrogenation: perfect quasi architecture (Ag@SiO₂NPs) as a substrate for nitrophenol reduction

Abstract

Spherical nanoparticles with core-frame architecture are a viable route to combine multiple functionalities on a nanoscopic scale. Amongst these nanoparticles, metal polymeric hybrid nanostructures exhibit significantly enhanced stability. Synergistic catalytic responses arise from quasi perfect morphology and their unique interactions between the metal and reactant substrate. Core-frame silver supported silica nanoparticles (Ag@SiO 2 NPs) with different frame thicknesses were tailored in a controlled manner through an oversimplified environmentally friendly route using simple chemical additives instead of dendrimers as linkers for prior modification of AgNPs. Here the optical and thermal properties of Ag@SiO 2 NPs were studied by high resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA).The resulting stabilised nature of Ag@SiO 2 NPs, their functionalization and environmental behaviour were analysed in detail through absorbance measurements. The control over the particle geometry provided an opportunity to utilise this hybrid NP as a temper for faster hydrogenation of p-nitrophenol with minimal reductant concentration (3 mM NaBH 4 ). The effect of the volume ratio of the hybrid catalyst with respect to thermal behaviour and their hydrogenation reaction time, average reaction rate and hybrid reusability were thoroughly investigated. The reported high performance towards faster hydrogenation was completed within 300 s at 25 C and 16 s at 60 C. The synergetic behaviour of core-frame morphology provides faster electron transfer for hydrogenation and enhanced thermal stability against poisonous environments.

Control of the Size of Silver Nanoparticles and Release of Silver in Heat Treated SiO2-Ag Composite Powders

“…The interaction between the Ag NPs and the matrix and functional groups in the composite samples were investigated by Fourier Transform Infrared spectroscopy (FTIR), as observed in Figure A3 . The two strong bands between 1000–1200 and 750–850 are ascribed to the asymmetric and symmetric Si–O–Si stretching vibrations, respectively [ 38 , 39 , 40 ]. The band around 950 originates from the Si–OH bonds [ 39 , 40 ].…”

Unique properties of silver and copper silica-based nanocomposites as antimicrobial agents

“…Analyzing the Ag/SiO 2 h spectrum, one can nd the slight red-shi about 10 cm À1 and broadening of main silica band, due to formation of the Si-O-Ag bond. 48 At the same time, the splitting of Si-O-Si band centered originally at 445 cm À1 on two bands centered at 429 cm À1 and 465 cm À1 points to the deformation of silica network as well as formation of the outer polymeric cage within silica network (Fig. 6C).…”

“…6C). 48,52 Further analysis showed weak intense bands observed on silver-silica infrared spectra located in the 1650-1750 cm À1 range. This band corresponds to the stretching vibration of C]O bond from the aldehyde group, while bands located in the 3200-3800 cm À1 range can be associated with stretching mode of n(Si-OH), n(OH) as well as molecular water adsorbed on the silica surface.…”

“…The results showed, that the SiO 2 spectrum is dominated by three characteristic absorption bands at 450-1500 cm À1 , which originate from Si-O-Si vibrations. 1,48,49 The band at 952 cm À1 is ascribed to the Si-OH bond, 1,49,50 while the rest of the them stems from structural deformation within silica network and from non-stoichiometric silicon oxide. 51 The pure Ag sample showed characteristic bands in the 1100-1800 cm À1 range (Fig.…”

X-ray investigations into silica/silver nanocomposite

“…The IR spectrum of the initial SiO 2 /Ag nanocomposite is presented in Figure 2. The spectrum is dominated by three absorption bands centered in the 400–1300 cm −1 region, ascribed to Si–O–Si vibrations (Ramalingam et al , 2014). In more detail, the deconvolution procedure points to the presence of bands centered at 960, 981 cm −1 , which originate from the Si–OH bond (Ramalingam et al , 2014), structural deformation within the silica network or non-stoichiometric silicon oxide (Zhao et al , 2011).…”