Ch. Venkata Reddy

Improved photocatalytic activity of MoS2 nanosheets decorated with SnO2 nanoparticles

MoS2 nanosheets decorated with SnO2 mesoporous nanoparticles were successfully prepared by a facile two-step method. The MoS2 nanosheets were pre-synthesized using a solvothermal method and then decorated with the SnO2 mesoporous nanoparticles through a wet chemical method. The nanocomposite was characterized with powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersed spectrometry (EDX), high-resolution transmission electron microscopy (HRTEM), thermal gravimetric and differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). SnO2 mesoporous nanoparticles can be selectively formed and attached to the peripheral surface of the layered MoS2, which was confirmed by FESEM and HRTEM. The photocatalytic activity of the nanocomposite was examined with Rhodamine B (RhB) in aqueous solution under UV light irradiation. The SnO2 nanoparticles remarkably suppressed the electron–hole recombination effect on the MoS2 photocatalyst and improved the photocatalytic activity compared to a pristine MoS2 catalyst. A higher rate of pollutant degradation was accomplished within 50 min that was three times higher than that of the pristine MoS2 catalyst.

Absorption and photoluminescence spectra of some rare earth doped B2O3TeO2BaOR2O (R = Li, Na, Li + Na) glasses

Abstract This paper reports the preparation and optical characterisation of certain rare earth (Sm3+, Dy3+, Eu3+) doped borotellurite glasses of the following composition: B2O3TeO2BaOR2OREF3 where R = Li, Na and Li + Na; RE = Sm3+, Dy3+ and Eu3+. From the measured spectra, absorption band intensity parametrisation and luminescence characteristic parameters have been evaluated for the glasses investigated. Under a UV source, it was observed that Sm3+ doped glasses have been luminescing in greenish-yellow, Dy3+ glasses in yellowish-blue and Eu3+ glasses in red colours. These optical glasses are found to be IR-transmitting (up to 4.5 μm) with good transparency and sufficient hardness.

Effect of Co2+ and Ni2+-doped zinc borate nano crystalline powders by co-precipitation method

A simple co-precipitation method has been used for the synthesis of Co(2+) and Ni(2+)-doped zinc borate nanopowders. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV/Vis absorption, Scanning electron microscope (SEM) with EDS and photoluminescence (PL) spectroscopies techniques has been employed for their characterization. Powder X-ray diffraction data reveals that the crystal structure belongs to monoclinic for both as-prepared samples. SEM images showed surface morphology of the prepared samples. Optical absorption spectra showed the characteristic bands of doped ions in octahedral site symmetry. From the optical absorption data crystal field and inter-electronic repulsion parameters are evaluated. The FT-IR spectra showed the characteristic vibrational bands related to ZnO, BO3 and BO4 molecules. Photoluminescence spectra exhibited the emission bands in ultraviolet and blue regions.

Structural and photoluminescence studies of Co2+ doped Ca–Li hydroxyapatite nanopowders

Co2+ doped Calcium–Lithium Hydroxyapatite (CLHA) nanopowders were prepared by mechanochemical synthesis and characterized by different techniques. From Powder XRD data, the crystal system belongs to hexagonal structure and lattice cell parameters, average crystallite size were evaluated. The morphologies of prepared samples were analyzed by using SEM and TEM studies. Optical and EPR data confirms that the doped Co2+ enter into host material as distorted octahedral site symmetry. PL studies of Co2+ doped CLHA nanopowders exhibit UV, blue and yellow emission bands. CIE chromaticity coordinates were also calculated from emission spectra of Co2+ doped CLHA nanopowders. Vibrational bands related to phosphate molecules, P–O–H and hydroxyl ions are observed in FT-IR spectra.