Supporting Information

Surface structural, morphological and catalytic studies of homogeneously dispersed anisotropic Ag nanostructures within mesoporous silica

Author’s name: Shweta Sareena, Vishal Mutrejab, Bonamali Pala and Satnam Singha*

aSchool of Chemistry and Biochemistry, Thapar University, Patiala 147004, Punjab, INDIA

bMaharishi Markandeshwar University, Mullana 133207, Haryana, INDIA

1.  Chemicals

Pluronic (M.W. 5800), tetraethoxysilane (TEOS), p-dinitrobenzene (DNB), p-nitroacetophenone (p-NAP), p-aminoacetophenone (p-AAP), p-nitrophenol (NP), p-aminophenol (AP), silver nitrate (AgNO3, 99.99%), p-phenylenediamine (PDA), p-nitroaniline (NA), sodium borohydride (NaBH4) and 3-aminopropyltrimethoxysilane (APTMS) were obtained from Sigma Aldrich. Various other reagents were obtained from Loba Chemie, India and used as received without further purification. Ultrapure de-ionized water (Milli-Q, Millipore) was used for all the experiments.

2.  Characterization

Panalytical X’pert Pro diffractometer was used to obtain Powder X-ray diffraction (XRD) patterns by using Cu Kα radiation (λ=1.54060 Å) within the 2θ range of 10-80 o (in steps of 0.0170 o with a scan step time of 21.32 s) and 0.5-5 o (in steps of 0.02 o with a scan step time of 86.19 s). Hitachi (H-7500) 120 kW was used to record transmission electron micrographs. HR-TEM, elemental mapping, and EDX studies were obtained with FEI Tecnai F20 microscope operating at 200 kV. X-ray photoelectron spectroscopy (XPS) data of the samples was taken on KRATOS-AXIS DLD spectrometer (Kratos Analytical, U.K.) equipped with monochromatic Al K ά radiation at 1486.6 eV operating at 10 kW. Binding energies were referenced to C1s binding energy of standard hydrocarbons (284.6 eV). Field Emission-Scanning electron microscopy (FE-SEM) images were obtained using a Hitachi SU8000 (serial number HI-0876-0003) at an accelerating voltage of 15 kV. Atomic Force Microscopy (AFM) was used for determining the surface morphology and nanostructures of the prepared mesoporous composites by means of NT-MDT NTEGRA (TS-150), a scanning probe microscope. All measurements were performed in air using tapping mode. In this method, the cantilever vibrates up and down, near to its resonance frequency so that the tip can follow the surface profile. When the tip is brought closer to the surface of the sample, then due to the interactions between the sample and the tip, the movement of the cantilever is affected. The resulting phase shifts of the cantilever w.r.t driving signal helps in providing information about surface properties such as roughness, stiffness, and adhesion. For AFM studies, silicon probes with a resonance frequency of 200-400 KHz and an extremely sharp tip (3-50 nm radius of curvature) were used. For analysis, pellets of the samples were prepared by mixing in equal proportions with a binder and then images with 10 × 10 μm were recorded. Various AFM parameters were calculated by using software NOVA 1424. Surface area (SBET) studies were determined by pretreating 20 mg of all samples at the 200 oC under vacuum for 2 h using a BET surface area analyzer (BEL Sorp-max). Cary 660 series Agilent FTIR spectrometer was used to record IR (Infra-red) spectra by KBr pellet method within the range of 400-4000 cm-1. Thermogravimetric analysis was carried out on TGA-50 Shimadzu Thermogravimetric analyzer under nitrogen with a heating speed of 10oC/min. Analytikjena Specord 205 spectrophotometer was used to record solid state UV-visible absorption spectra in the range of 400-800 nm. The Ag loading of the samples was estimated using Agilent Microwave Plasma-Atomic Emission Spectrometer (MP-AES). Prior to the determination, the samples were treated with aqua regia for 30 min. and heated till evaporation. Finally, the samples were diluted with 5 % HNO3 and filtrated to 20 ml volumetric flask.

Fig S1. Particle size histograms of (a) 2 wt. %, (b) 4 wt. % and (c) 5 wt. % Ag/m-SBA-15 catalysts.

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Fig S2. HR-TEM image of 4 wt. % Ag/m-SBA-15 catalyst.

Fig S3. (a) Nitrogen adsorption- desorption isotherms and (b) pore size distribution of bare SBA-15 and various wt. % Ag/m-SBA-15 catalyst.

Fig S4. XPS spectra of 4 wt. % Ag/m-SBA-15 catalyst.

Fig S5. HPLC chromatograms of reaction sample for p-dinitrobenzne reduction at 20 min. catalysed by 4 wt. % Ag/m-SBA-15 catalyst.

Fig S6. HPLC chromatograms of reaction sample for p-nitrophenol reduction at 8 min. catalysed by 4 wt. % Ag/m-SBA-15 catalyst.

Fig S7. HPLC chromatograms of reaction sample for p-nitroacetophenone reduction at 60 min. catalysed by 4 wt. % Ag/m-SBA-15 catalyst.

Fig S8. (a) Low angle XRD pattern and (b) TEM image of reused (4 wt. % Ag/m-SBA-15 ) catalyst after three recycles.