Department of Physics

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Physics

A ternary Cu2O/MoS2/rGO (Cu2MG) composite, synthesized by cost-efficient and eco-friendly microwave method, is potentially used for the sonophotocatalytic (visible light and ultrasonic irradiation) degradation of antibiotics namely tetracycline and ciprofloxacin. SEM and TEM observations reveal that the spherical Cu2O nanoparticles are decorated with MoS2 and rGO layered sheets. Furthermore, the incorporation of MoS2/rGO binary composite to Cu2O nanoparticles results in the reduction in fast electron-hole recombination and improve charge carrier ability of Cu2MG composite as confirmed by PL analysis. The Cu2MG composite demonstrates the synergic sonophotocatalytic degradation of Tetracycline (20 mg/L) and Ciprofloxacin (10 mg/L) antibiotics with high efficiency of 100% and 94% within a short duration of 10 min and 75 min, respectively. The kinetics study indicates that the degradation process obeys a pseudo-first order reaction with a rate constant as Ksonophotocatalytic &gt; Kphotocatalytic &gt; Ksonocatalytic. The high synergic value of 3.83 and 1.71 has been achieved for the degradation of TC and CIP antibiotics, respectively. The synergic effect of degradation is owing to the spontaneous production of OH˙ and ˙O2− radicals favoring free electrons to actively participate in the degradation process. This research work proves that the as-fabricated ternary Cu2MG nanocomposite is an efficient candidate for the degradation of antibiotics for better environmental protection. © 2020 Elsevier Ltd and Techna Group S.r.l.

World University root node

School of Advanced Sciences

Chennai Campus

Ceramics International

Synergic effect of Cu2O/MoS2/rGO for the sonophotocatalytic degradation of tetracycline and ciprofloxacin antibiotics

Herein, we report the one-pot synthesis of WO3/RGO composite and its efficient electrochemical activity in catechol (CC) oxidation. Anchoring of 1-D WO3 microrods on 2-D RGO nanosheets were confirmed through the detailed physicochemical analyses (XRD, FESEM, XPS, Raman). Availability of large electrocatalytically active surface area yields the conductivity enrichment as well as significantly improved redox properties in WO3/RGO composite. Further, a 20-fold intensified oxidation signal in CV and a 4-fold increased sensitivity from differential pulse voltammetry (DPV) support the superior electron transfer rate at the surface of WO3/RGO composite. Oxidation of CC involving the transfer of two electrons via a diffusion controlled process was revealed by the electrochemical approaches. From density functional theory (DFT) simulations, the charge transfer from O 2p orbital of catechol to W 4d orbital of WO3 facilitate the oxidation of catechol molecule. Z-scan study explored the strong reverse saturable absorption at 532 nm excitation and the third-order nonlinear optical susceptibility χ(3) of 9.727 × 10−8 esu was obtained for WO3/RGO. Hence, the hydrothermally prepared WO3/RGO composite with its excellent redox properties and negative nonlinearity could be a competent material to use in electrochemical sensing and optical limiting. © 2020 Elsevier B.V.

Applied Surface Science

Bifunctional WO3 microrods decorated RGO composite as catechol sensor and optical limiter

In this paper, we have computed the dimensions of the vector space of relative symmetric polynomials with respect to all irreducible characters of the projective special linear group P SL2(F7). © 2021, International Journal on Emerging Technolgies. All rights reserved.

Mathematics

Advances in Mathematics: Scientific Journal

Formula for the dimensions of the relative invariants of projective special linear group p sl2(F7)

Single crystal of p-Toluidinium L-Tartrate (PTLT) was harvested via slow solvent evaporation technique. The grown PTLT crystal has a triclinic structure, P1 space group. Functional groups were affirmed by FT-IR spectroscopy. The absorption coefficient (α), energy bandgap, and linear refractive index (n0) were estimated from the UV-Vis-NIR spectrum. A broad emission band observed at 350 nm in the luminescence spectrum of PTLT, corresponds to violet light emission. The dielectric constant and loss were determined by varying the frequency and temperature. The mechanical parameters were determined by the micro-indentation test for various loads. The SHG efficiency of the compound was measured by the powder Kurtz-Perry method. The NLO parameters n2 (1.731 × 10‒9 cm2W−1), β (0.079 × 10‒4 cm W−1), and χ(3) (9.05 × 10‒7 esu) were determined by the Z-scan method. In addition, antibacterial activity was carried out against selected foodborne pathogens for pharmaceutical applications. © 2020

Fulltext

Chemical Data Collections

Investigation on nonlinear optical and antibacterial properties of organic single crystal: p-Toluidinium L-Tartrate

The structural and nonlinear optical properties of the Schiff base material, (E)-4-fluoro-N′-(pyridin-2-ylmethylene)benzohydrazide monohydrate (FPMBH) were studied. The experimental investigations were performed using Fourier transform infrared (FTIR), ultraviolet (UV) and nuclear magnetic resonance (NMR) spectral techniques. The computational analyses were made by DFT method. A comparison between experimental and theoretical predictions was made and interpreted. The maximum absorption wavelength was found by both experimental and theoretical analyses. The Hirshfeld surface analysis was performed to understand the various molecular interactions. Highest occupied and lowest unoccupied molecular orbitals (HOMO–LUMO) analysis was performed for the title molecule to know about the possible charge transfer taking place within the molecule. Reactivity features were also determined by molecular electrostatic potential (MEP) analysis. The third-order nonlinear optical studies were done by z-scan experiment, and the results were discussed. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.

Research on Chemical Intermediates

Structural, spectral, experimental, and theoretical investigations of (E)-4-fluoro-N′-(pyridin-2-ylmethylene)benzohydrazide monohydrate

Graphene (GR) photodetector devices have broad-range absorption, whereas WO3 devices are known to be sensitive to the ultraviolet (UV) radiation. In this work, we mainly focus on developing a hybrid bilayer of a WO3/GR photodetector device, which is sensitive to detect both UV and visible radiations. Introduction of GR onto WO3 would tune the device to sense visible light and also enhances the photocurrent under UV illumination. The final device can be expected to show good photocurrent, responsivity, and detectivity with minimized shot noise under the illumination of both UV and visible lights. This study provides a detailed mechanism of how the photoelectrons are drawn into GR without being trapped into WO3 due to the presence of the built-in electric field at the GR and WO3 interface and also explains in what manner this in-built field, applied bias voltage, and defect states assist for achieving the superior and tunable UV-visible photodetectors. © 2021 American Chemical Society.

ACS Applied Electronic Materials

Enhanced Performance of WO3Photodetectors through Hybrid Graphene-Layer Integration

A new organic single crystal viz, piperazinium bis(5-chlorosalicylate) (P5C) was grown by low temperature solution growth method and its physico-chemical properties were established. The unit cell parameters (a = 11.9306 Å, b = 8.7592 Å, c = 9.3103 Å, α = 90°, β= 100.95°, γ = 90°) were determined by single crystal X-ray diffraction data. The presence of various functional groups in the structure was elucidated by FTIR, Raman and proton NMR spectral studies. The P5C crystal exhibits the good optical tansmittance in the region of 400 to 1200 nm. From photoluminescence studies, the violet emission spectrum was observed under the excitation wavelength of 380 nm. The thermal behaviour of the P5C crystal was analyzed by TG-DSC analysis. The mechanical strength of the grown material classifies it as soft material. The results from Z-scan technique validate the NLO properties. Theoretical calculations like optimized geometry, HOMO-LUMO, mulliken population analysis, natural bond analysis were determined using Gaussian 09W with B3LYP method. © 2020 Elsevier B.V.

Journal of Molecular Structure

Piperazinium bis (5-chlorosalicylate) – A new third order nonlinear optical single crystal

A single crystal of nonlinear optical material Benzimidazolium Benzilate (BDBA) with dimensions 0.2 × 0.2 × 0.18 mm3 was successfully grown by slow evaporation technique. The BDBA crystal crystallizes in the monoclinic crystal system with centrosymmetric space group C2/c. The intermolecular interactions were estimated through the Hirshfeld surface analysis. The vibrational modes of functional groups present in the compound were confirmed through attenuated total reflectance spectral studies. The molecular structure of BDBA was ascertained using NMR spectroscopic measurements, and the results confirmed the migration of proton from benzilic acid to Benzimidazole. Photoluminescence spectra indicate violet fluorescence emission peaks at 350 nm excitation. The optical band gap was 4.39 eV with a transmittance cut off wavelength of 282 nm. The extinction coefficient, optical and electrical conductivity, susceptibility, and polarization were calculated using UV–Vis-NIR spectroscopic measurements. The thermal properties were assessed by the simultaneous study of thermogravimetric (TG) and differential thermal analysis (DTA). It shows that the compound withstands up to a temperature of 148 °C. The crystal properties were theoretically computed using density functional theory (DFT) at the level of RB3LYP/6–311 + G(d,p) and computational studies such as natural bond orbital analysis, molecular electrostatic potential, Mulliken atomic charge distribution, and HOMO-LUMO were performed. The third order nonlinear optical (NLO) properties were studied using Z-scan studies. © 2021

Chemical Physics Letters

An organic benzimidazolium benzilate (BDBA) crystal: Structural description, spectral investigations, DFT calculations, thermal, photoluminescence, linear and nonlinear optical analysis

In this work, organic new bis (2-amino-6-methylpyridinium 3,4-dimethoxybenzoate) dihydrate (2A6MD) single crystal was grown by slow evaporation method with the dimensions 20 × 4 × 10 mm3. The structure of grown crystal was confirmed via the single crystal X-ray diffraction. It showed that 2A6MD compound crystallizes in a monoclinic crystal system with Centro symmetric space group P21/n. Powder X-ray diffraction analysis confirmed the crystalline nature 2A6MD crystal. FT-IR and 1H NMR spectra were carried out to confirm the functional groups and various hydrogen exposures in the 2A6MD crystal. UV-Vis spectrometer studies showed that 2A6MD crystal has a lower cut-off wavelength in the UV region and good optical transmittance in the entire visible region. Photoluminescence spectrum reveals the high emission peak at 366 nm with an excitation wavelength of 334 nm. Thermal stability and melting point of the synthesized 2A6MD crystal were investigated using TG-DSC measurement. Vickers's micro hardness test declares that mechanical stability of the grown crystal and their yield strength, elastic stiffness values were evaluated. The chemical etching was analyzed on the 2A6MD surface and the results expressed the growth feature of the crystal. Nonlinear absorption co-efficient, nonlinear refraction and third order susceptibility of synthesized 2A6MD crystal was evaluated by the Z- scan method. The density functional theory (DFT) computations with B3LYP/6-311++G (d,P) basis set to theoretically optimize the molecular geometry, HOMO-LUMO energies, molecular electrostatic potential, NBO analysis and first order hyperpolarizability of 2A6MD confirmed the nonlinear property. © 2021 The Physical Society of the Republic of China (Taiwan)

Chinese Journal of Physics

Physicochemical and quantum chemical calculations on new bis (2-amino-6-methylpyridinium 3,4–dimethoxybenzoate) dihydrate organic single crystal for third order nonlinear optical applications