International Journal of Nanoscience

CuInSe₂ (CIS)-based powders were successfully prepared by a facile refluxing reaction route using metal halides and Se/S powder as raw starting materials. The phase and crystallographic structure, morphology, chemical composition of the products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS). It is found that single phase CIS powders with chalcopyrite structure can be prepared in a relatively short time using triethylenetetramine as the solvent; the most suitable reaction temperature and time are 200°C, 1–2 h, respectively. CuIn(S_xSe_1-x)₂ powders were also prepared by refluxing reaction route using the mixed solvent of triethylenetetramine–glycol (1:1, v/v). The characterizations showed that the CuIn(S_xSe_1-x)₂ has single chalcopyrite phase, and the stoichiometric composition closely follows the primary mixed ratio. The morphology of CuIn(S_xSe_1-x)₂ is close to spheres, and the particle sizes become distinctly smaller with the incorporation of S. A possible formation mechanism of CuInSe₂ was put forward and briefly discussed.

The wurtzite phase of ZnS-nanorods (NRs) (length 100–120 nm and width 10–15 nm) has been prepared by solvothermal method and 1 wt.% Au and Pt nanoparticles (2–5 nm) were photodeposited and sintered at 500°C for 2 h. ZnS-NR exhibits an exciton band at 283 nm and absorption onset at 304 nm (bandgap = 4.06 eV) as compared to 336 nm (bandgap = 3.77 eV) of bulk ZnS, indicating its quantum size effect. The absorption is red shifted to ~350 nm and ~366 nm after Au and Pt deposition, and also sintering led to quench the ZnS absorption band in UV region due to the exciton–plasmon interactions. Photoluminescence (PL) of ZnS-NRs (band at 366–377 nm) is significantly reduced after Au or Pt deposition and sintering. The photocatalytic activity of p-nitrophenol (PNP) degradation has been appreciably improved (rate constants k = 3.6 × 10^-3 min^-1 and k = 3.6 × 10^-3 min^-1) after 1 wt.% Pt loading on ZnS followed by sintering at 500°C for 2 h as compared to bare (k = 1.2 × 10^-3 min^-1) and sintered ZnS(k = 3.3 × 10^-3 min^-1) catalyst, respectively. Similarly, Au loading and sintering led to increased the k = 2.7 × 10^-3 and 4.5 × 10^-3 min^-1 relative to bare ZnS-NR and direct photolysis (k = 0.3 × 10^-3 min^-1) of PNP under UV light (10.4 mWcm^-2) irradiation. Sintering appreciably improves the ZnS (surface area = 58.9 m²g^-1) photoactivity due to better crystallinity and removal of defect sites.

In this work, we report the successful formation of MgO doped TiO₂ nanocrystals (NCs) by simple wet-chemical method. The XRD exhibits a marginal decrease in the crystalline size of TiO₂ nanosamples by the addition of MgO dopant. UV–Vis spectral analysis shows that the addition of MgO in TiO₂ resulted in the red shift of the absorption edge. The optical energy band-gap and molecular vibrational analysis of doped nanosample was ascertained from photoluminescence (PL) and micro-Raman scattering technique respectively. HR-TEM analysis reveals that the substitution has sharply reduced the particle size of TiO₂NCs.

This work reports the low-cost exfoliation of graphene oxide (GO) from pencil lead using modified Hummer's method. The gold nanoparticles (AuNPs) supported on GO is prepared via an in situ bio reduction of HAuCl₄ by polyphenolic biomolecules present in young leaves of tea (Camellia sinensis) extracted in the presence of GO. The UV-Visible absorption spectrum of GO dispersion in water exhibits two bands at 228 nm and a shoulder at ~ 300 nm corresponding to π–π* transitions of aromatic C–C bonds and n–π* transitions of C=O bonds. In photoluminescence (PL) study, GO dispersion in water shows an emission band at 555 nm, when excited at 325 nm. When AuNPs are supported on GO nanosheets the bands at 228 nm and ~ 300 nm of GO disappears and two new UV-Visible bands at 229 nm for π–π* (for C=C) and 550 nm for transverse surface plasmon resonance (TSPR) of AuNPs appears. When AuNPs are supported on GO nanosheets, PL emission band at 555 nm disappears and two new PL emission bands appear at 431 nm and 658 nm. The physical and morphological characterizations are performed by Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), High-resolution-transmission electron microscopy (HR-TEM) and BET surface area measurement. Morphological studies revealed that the GO nanosheets are well dispersed in water and AuNPs are supported on the GO nanosheets.

Bi₂WO₆ microspheres constructed from nanosheets have been synthesized by a controllable solvothermal route in a large scale. The structure characterizations of the microspheres were investigated in detail by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). On the basis of XRD analysis and SEM observation of the products at different reaction time periods, a growth mechanism of Bi₂WO₆ microspheres was proposed. UV-Visible diffuse reflectance (DR) spectrum of the prepared Bi₂WO₆ microspheres demonstrates that they have absorption in the visible light region. The photocatalytic activity of Bi₂WO₆ microspheres toward Rhodamine-B (RhB) degradation was investigated and the as-prepared products exhibited good photocatalytic activity in degradation of RhB under 300 W Xe lamp light irradiation.

We report the synthesis of copper oxide (CuO) nanoparticles prepared by wet chemical precipitation method. The structural and dielectric properties are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and complex impedance spectroscopy as a function of frequencies from 40 KHz to 100 KHz in the range of temperatures (308–393K). Maximum value of dielectric constants are found to be in the order of 10⁶ which increases with increase in temperatures. From XRD data it is found that the particle size increases with increase in calcination temperatures. SEM with energy dispersive X-ray fluorescence spectrometer (EDX) results show that only CuO is present in the prepared sample. The selected area electron diffraction (SAED) pattern by TEM shows that uniform size distributions of CuO nanoparticles are present in the sample.

Double-matrix hierarchical structure of the 〈molecular-lattice matrix MCM-41〈hydroquinone〉〉 is synthesized. Its use in the cathode process in the Li⁺-intercalation current generation showed a significant improvement in the structure of the discharge curve and the practical constancy of diffusion coefficient throughout the discharge process. Theoretical model describing the peculiarities of observed characteristics in the structure is presented.

Orthorhombic phase of antimony triselenide (Sb₂Se₃) nanowires have been obtained by a facile and effective one-pot noninjection chemical route with controllable shape and size. The synthesis, which uses SeO₂ as the selenium precursor and can be conducted in air, is suitable for the larger-scale industrial synthesis of high-quality nanocrystals at low cost. The as-prepared nanocrystals were extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). We believe that the method present here is a more straightforward and cost-effective route to prepare Sb₂Se₃ nanocrystals with high quality. The band-edge positions of the Sb₂Se₃ nanocrystals are studied by cyclic voltammetry (CV).

Silver nanoparticles were generated using laser ablation technique in emulsified isobutyl acrylate solution in which the nanoparticles are stabilized and embedded over the acrylic polymerized solution. Further, the colloidal solutions were characterized with atomic force microscope (AFM), scanning electron microscope (SEM) and Fourier transform infrared spectrophotometer (FTIR). AFM image results of the nanoparticles displays the silver nanoparticles embedded over the emulsified acrylic layer and dispersion of spherical nanoparticles across the polymer were eruptions of silver nanoparticles can be seen clearly. In addition, FTIR spectrum and SEM images validate the nanoparticle reaction over the polymerized acrylate solution and size of the metal nanoparticles respectively.