Articles written in Journal of Chemical Sciences

• Effect of metal ion doping on the photocatalytic activity of aluminophosphates

The metal ions (Ti+4, Mg+2, Zn+2 and Co+2) have been substituted in place of Al$^{+3}$ in aluminophosphates (AlPOs). These compounds were used for the first time as possible photocatalysts for the degradation of organic dyes. Among the doped AlPOs, ZnAlPO-5, CoAlPO-5, MgAlPO-11, 18 and 36 did not show any photocatalytic activity. MgAlPO-5 showed photocatalytic activity and different loading of Mg (4, 8, 12 atom % of Mg) were investigated. The activity can be enhanced by the increasing of concentration of the doped metal ions. TiAlPO-5 (4, 8, 12 atom % of Ti) showed the highest photocatalytic activity among all the compounds and its activity was compared to that of Degussa P25 (TiO2). The activity of photocatalysts was correlated with the diffuse reflectance and photoluminescence spectra.

• Synthesis, structure and ionic conductivity in scheelite type Li0.5Ce$_{0.5−x}$Ln$_x$MoO4 ($x = 0$ and 0.25, Ln = Pr, Sm)

Scheelite type solid electrolytes, Li0.5Ce$_{0.5−x}$Ln$_x$MoO4 ($x = 0$ and 0.25, Ln = Pr, Sm) have been synthesized using a solid state method. Their structure and ionic conductivity (𝜎) were obtained by single crystal X-ray diffraction and ac-impedance spectroscopy, respectively. X-ray diffraction studies reveal a space group of $I4_1/a$ for Li0.5Ce$_{0.5−x}$Ln$_x$MoO4 ($x = 0$ and 0.25, Ln = Pr, Sm) scheelite compounds. The unsubstituted Li0.5Ce0.5MoO4 showed lithium ion conductivity $\sim 10^{−5}-10^{−3} \Omega^{−1}$cm-1 in the temperature range of 300-700°C ($\sigma = 2.5 \times 10^{−3} \Omega^{−1}$cm-1 at 700°C). The substituted compounds show lower conductivity compared to the unsubstituted compound, with the magnitude of ionic conductivity being two (in the high temperature regime) to one order (in the low temperature regime) lower than the unsubstituted compound. Since these scheelite type structures show significant conductivity, the series of compounds could serve in high temperature lithium battery operations.

• Ce0.98Pd0.02O$_{2-\delta}$: Recyclable, ligand free palladium(II) catalyst for Heck reaction

Palladium substituted in cerium dioxide in the form of a solid solution, Ce0.98 Pd0.02 O1.98 is a new heterogeneous catalyst which exhibits high activity and 100% trans-selectivity for the Heck reactions of aryl bromides including heteroaryls with olefins. The catalytic reactions work without any ligand. Nanocrystalline Ce0.98 Pd0.02 O1.98 is prepared by solution combustion method and Pd is in +2 state. The catalyst can be separated, recovered and reused without significant loss in activity.

• Photocatalytic properties of KBiO3 and LiBiO3 with tunnel structures

In the present study, KBiO3 is synthesized by a standard oxidation technique while LiBiO3 is prepared by hydrothermal method. The synthesized catalysts are characterized by X-ray diffraction (XRD), Scanning ElectronMicroscopy (SEM), BET surface area analysis and Diffuse Reflectance Spectroscopy (DRS). The XRD patterns suggest that KBiO3 crystallizes in the cubic structure while LiBiO3 crystallizes in orthorhombic structure and both of these adopt the tunnel structure. The SEM images reveal micron size polyhedral shaped KBiO3 particles and rod-like or prismatic shape particles for LiBiO3. The band gap is calculated from the diffuse reflectance spectrum and is found to be 2.1 eV and 1.8 eV for KBiO3 and LiBiO3, respectively. The band gap and the crystal structure data suggest that these materials can be used as photocatalysts. The photocatalytic activity of KBiO3 and LiBiO3 are evaluated for the degradation of anionic and cationic dyes, respectively, under UV and solar radiations.

• Transition metal oxide loaded MCM catalysts for photocatalytic degradation of dyes

Transition metal oxide (TiO2, Fe2O3, CoO) loaded MCM-41 and MCM-48 were synthesized by a two-step surfactant-based process. Nanoporous, high surface area compounds were obtained after calcination of the compounds. The catalysts were characterized by SEM, XRD, XPS, UV-vis and BET surface area analysis. The catalysts showed high activity for the photocatalytic degradation of both anionic and cationic dyes. The degradation of the dyes was described using Langmuir-Hinshelwood kinetics and the associated rate parameters were determined.

• Synthesis and characterization of nano silicon and titanium nitride powders using atmospheric microwave plasma technique

We have demonstrated a simple, scalable and inexpensive method based on microwave plasma for synthesizing 5 to 10 g/h of nanomaterials. Luminescent nano silicon particles were synthesized by homogenous nucleation of silicon vapour produced by the radial injection of silicon tetrachloride vapour and nano titanium nitride was synthesized by using liquid titanium tetrachloride as the precursor. The synthesized nano silicon and titanium nitride powders were characterized by XRD, XPS, TEM, SEM and BET. The characterization techniques indicated that the synthesized powders were indeed crystalline nanomaterials.

• # Journal of Chemical Sciences

Volume 132, 2019
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Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019