Fabrication of Adsorbed Fe(III) and Structurally Doped Fe(III) in Montmorillonite/TiO2 Composite for Photocatalytic Degradation of Phenol

The Fe(III)-doped montmorillonite (Mt)/TiO2 composites were fabricated by adding Fe(III) during or after the aging of TiO2/Ti(OH)4 sol–gel in Mt, named as xFe-Mt/(1 − x)Fe-TiO2 and Fe/Mt/TiO2, respectively. In the xFe-Mt/(1 − x)Fe-TiO2, Fe(III) cations were expected to be located in the structure of TiO2, in the Mt, and in the interface between them, while Fe(III) ions are physically adsorbed on the surfaces of the composites in the Fe/Mt/TiO2. The narrower energy bandgap (Eg) lower photo-luminescence intensity were observed for the composites compared with TiO2. Better photocatalytic performance for phenol degradation was observed in the Fe/Mt/TiO2. The 94.6% phenol degradation was due to greater charge generation and migration capacity, which was confirmed by photocurrent measurements and electrochemical impedance spectroscopy (EIS). The results of the energy-resolved distribution of electron traps (ERDT) suggested that the Fe/Mt/TiO2 possessed a larger amorphous rutile phase content in direct contact with crystal anatase than that of the xFe-Mt/(1 − x)Fe-TiO2. This component is the fraction that is mainly responsible for the photocatalytic phenol degradation by the composites. As for the xFe-Mt/(1 − x)Fe-TiO2, the active rutile phase was followed by isolated amorphous phases which had larger (Eg) and which did not act as a photocatalyst. Thus, the physically adsorbed Fe(III) enhanced light adsorption and avoided charge recombination, resulting in improved photocatalytic performance. The mechanism of the photocatalytic reaction with the Fe(III)-doped Mt/TiO2 composite was proposed.

Tailored TiO2 Nanorod Arrays for Dye Sensitized Solar Cell Applications

A TiO2 layer using titanium (IV) butoxide on fluorine doped tin oxide (FTO) substrate is used as a seed layer for the growth of 2D-TiO2 arrays (TRA). TRAs with length of ~1 to 2 µm were grown on seed layer (SL) by two step method. In the first step TiO2 SLs were deposited by sol-gel assisted spin coating method and the second step involved the typical hydrothermal technique to grow rutile TRAs. Most of the TRAs grown on FTO substrate without SL were randomly oriented and TRAs with 0.025M SL was oriented vertically from the substrate. Whereas TRAs grown on 0.05M SL showed hierarchical nanoflower clusters composed of a bunch of TRAs as petals blooming to all directions from the core. The XRD pattern showed all the three TRAs to be crystallized in a tetragonal rutile phase. Photo Luminescence spectra revealed that the TRAs on 0.05M SL have comparatively low intense blue emission band, predicting the suppressed electron-hole recombination rate. The power conversion efficiency of the dye sensitized solar cell (DSSC) with TRAs grown on 0.05M SL was recorded as 3%, which is 3 times greater than that without SL and 1.6 times greater than that with 0.025M SL in our observations.

Photo-Luminescence study of Ba3Gd1-x(BO3)3 : X Ce3+ phosphor

The polycrystalline powder sample of Ce3+ activated barium gadolinium borate phosphors Ba3Gd1-x(BO3)3 : X Ce3+(0.01 ≤ X ≤ 0.06 ) are prepared by solution combustion. Formation of phosphor in desired crystalline phase confirmed by powder XRD characterization & FTIR. A SEM image shows the irregular grains with average particle size 2.5μm. The excitation spectrum consists of a single broad absorption band from 200 to 400 nm with the prominent excitation peak at 343 nm [2F5/2 to 5D1 of Ce3+ ions]. Strongest emission peak of 488nm [5D1→ 2F5/2] and weak of 501nm [5D1→ 2F7/2] wavelength which is of blue light is observed at 343nm UV light excitation. Ba3Gd1-x(BO3)3 : X Ce3+ phosphor emits blue light under UV excitation. Maximum PL emission takes place at 3 mole percentage of Ce3+. Concentration quenching for Ce3+ ions is studied. Hence Ba3Gd1-x(BO3)3 : X Ce3+ is new UV excited blue emitting phosphor useful for UV/Blue chip WLEDs.

Studies on Structural, optical and Magnetic properties of Yttrium Aluminum Bromate (YAB) Nanomaterials, prepared at high annealing temperature

In this research, we present structural, photo-luminescence and magnetic properties of the Yttrium Aluminum Borate (YAB) nanomaterial, synthesized by low-cost Sol-gel method in high temperature range. X-ray diffraction (XRD) analysis, shows that crystal structure of YAB is of nanometric size ranging between 38 nm to 47 nm for the annealing temperature above 900°C. Photoluminescence property shows that YAB gives intense Blue light emission in the visible region. High-temperature annealing was found to increase the grain size and enhance the blue luminescence. Vibrating Sample Magnetometer (VSM) shows that coercivity increases while Magnetization and retentivity decreases for YAB nanomaterials for the temperature above 900 degree Celsius. Prepared YAB materials may be useful for LED or related devices.

Heterometal Grafted metalla-ynes and Poly(metalla-ynes): A Review on Structure–Property Relationships and Applications

Metalla-ynes and poly(metalla-ynes) have emerged as unique molecular scaffolds with fascinating structural features and intriguing photo-luminescence (PL) properties. Their rigid-rod conducting backbone with tunable photo-physical properties has generated immense research interests for the design and development of application-oriented functional materials. Introducing a second d- or f-block metal fragment in the main-chain or side-chain of a metalla-yne and poly(metalla-yne) was found to further modulate the underlying features/properties. This review focuses on the photo-physical properties and opto-electronic (O-E) applications of heterometal grafted metalla-ynes and poly(metalla-ynes).

Synthesis, Characterization, Photo-Luminescence and Antibacterial Activities of Silica-Graphene Oxide Composites

In this research, a novel thin film Si-GO10 and nano-powders Si-GO30 of silica-graphene oxide composite were prepared via sol-gel method and deposited on glass substrates using spray pyrolysis. XRD results showed a relatively strong peak in graphite layer that corresponds to the plane of (002). TEM images displayed that SiO₂ nano-particles were randomly distributed on the surface of Si-GO30 sample, and the particle size in these nano-powders was below 50 nm. Moreover, silica nano-particles on the surface of GO plates exhibited almost a spherical and rod-like nanoparticles shapes, which in turn confirmed the formation of SiO₂-GO nano-hybrids. FESEM analysis reveals a different morphology, the Si-GO10 sample is so rough and crumble, while the Si-GO30 sample is relatively smooth on the surface. Photocatalytic investigations revealed the composite materials exhibit high activity for dye adsorption and decomposition. Si-GO10 thin film did not undergo degradation after 120 minutes, however, for Si-GO30 nano-powder, the adsorption peak intensity was reduced to 665 nm, indicating a decrease in the dye concentration in the solution. FTIR analysis demonstrated that carboxylic functional groups are decreased by increasing silica particles. Photo-Luminescence (PL) spectrum in Si-GO10 thin film disclosed a severe emission peak at about 675 nm. This spectrum was completely disappeared in Si-GO30 nano-powders. Results of the antibacterial properties emphasized that Si-GO30 nano-particle would prevent Escherichia. coli growth after 20 hours. The presented methodology allows for the synthesis of graphene oxide supported silicon dioxide nano-particles for promising applications in photocatalytic and antibacterial fields.

An Efficient Nonlinear Optical, Magnetic Transition Metal Ion Nickel Doped L- Threonine Cadmium Acetate Monohydrate

The semi organic nonlinear optical single crystal of L- Threonine Cadmium acetate Monohydrate (LTCAM) doped Ni 2+ion is prepared by the technique slow evaporation solution growth. The prepared crystal was analysed by XRD, EDAX, UV-Vis- NIR, IR, TG/DTA, Photo Luminescence (PL), VSM and SHG measurements. The SXRD shows the crystal come under the monoclinic crystal system with P21 noncentrosymmetric space group. In the visible and near infrared region the crystal shows good optical response and it is a thermally stable compound. The band gap of the grown crystal was 5.02ev. The functional groups are confirmed by FTIR analysis. The luminescent behaviour of the doped crystal shows its ability as UV filters. The dopant turns its magnetic property in to semi paramagnetic nature.