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

Chemistry

Environmental deterioration and depletion in conventional energy resources greatly demand the need for photovoltaic devices, which use solar radiation to meet future energy demands. Efficient light management plays a pivotal role in improving the performance of photovoltaic devices. Various avenues have been explored to address light management in solar cells. Employing whispering gallery mode (WGM) microresonators in solar cell device is one such strategy. Using resonating structures for light scattering is recently gaining momentum as they exhibit great potential to enhance the efficiency through light trapping. Functional material-based microresonators further provide an added advantage as they combine inherent optical resonance with the material properties suitable for photovoltaics like efficient charge separation and transport in one platform. “Whisperonic solar cell” is a broadly classified device in which resonating cavities are used in the cell architecture to effectively scatter the light, resulting in enhanced light absorption and thus efficiency. Recent studies reveal that WGM-enabled optical microcavities can effectively get coupled to the light absorber in a sensitized solar cell (SSC) and improve the performance of SSC significantly. In this short review, we briefly present the idea of enhancing the efficiency of solar cell using WGMs. Several case studies available from the literature for realizing the concept of WGM for light trapping are highlighted. Particular focus is given to the quantum dot sensitized whisperonic solar cells. The concept is much more universal and will be useful in both thin-film and sensitized solar cells. © Copyright © 2019 Cholasettyhalli Dakshinamurthy, Das, Ilaiyaraja and Sudakar.

World University root node

School of Advanced Sciences

Chennai Campus

Fulltext

Frontiers in Materials

Quantum Dot Sensitized Whisperonic Solar Cells—Improving Efficiency Through Whispering Gallery Modes

Synthesis and reactivity studies of manganese(v)-oxo species in the C–H activation of alkyl hydrocarbons and epoxidation of cyclohexene in aqueous conditions are investigated.

New Journal of Chemistry

A putative heme manganese(v)-oxo species in the C–H activation and epoxidation reactions in an aqueous buffer

The recovery of actinides such as U(VI) and Th(IV) from nuclear waste is a critical challenge and it requires the development of novel selective and high-capacity sequestering materials. Herein a novel chelating adsorbents are prepared by grafting poly(amido)amine (PAMAM) and diglycolamic acid (DGA) functionalized PAMAM dendron on styrene divinyl benzene (SDB) solid support. Adsorption of U(VI) and Th(IV) from simulated nuclear liquid waste (SNLW) using PAMAM–SDB and DGA–PAMAM–SDB chelating resins were carried out. Our studies have found that PAMAM–SDB and DGA–PAMAM–SDB chelating resins exhibited good adsorption selectivity for U(VI) and Th(IV) at pH 5.5 in presence of other metal ions. In addition, these chelating resins finds potential application for total decontamination of SNLW at pH 12. Hence, PAMAM–SDB and DGA–PAMAM–SDB are promising chelating resins for selective removal of U(VI) and Th(IV) and also total decontamination of aqueous radioactive waste. © 2019, Institute of Chemistry, Slovak Academy of Sciences.

Chemical Papers

Adsorption of U(VI) and Th(IV) from simulated nuclear waste using PAMAM and DGA functionalized PAMAM dendron grafted styrene divinylbenzene chelating resins

One step electrodeposition method has been used to realize highly porous ZnO pin hole (ZP)and ZnO rosette sheets (ZS)nanostructure based photo-anodes for efficient photoelectrochemical (PEC)splitting of water. Electrodeposited ZP and ZS based photo-anodes exhibit enhanced photocurrent density of 0.62 mA/cm2 and 0.76 mA/cm2 respectively (at a bias of 0.75 V). Further on hydrothermal amination (A), these electrodeposited ZP and ZS (A-ZP and A-ZS)nanostructure based photo-anodes had shown enhanced photocurrent density of 1.02 mA/cm2 and 1.27 mA/cm2, respectively. Surface morphology, evolution and elemental study were done using FESEM and EDX. Raman spectra of aminated photo-anodes have peaks at ∼270 cm−1 and ∼511 cm−1 related to stretching vibration mode between Zn[sbnd]N and Zn[sbnd]O. The peaks at wave number ∼558 cm−1 and ∼571 cm−1 is due to formation of Zn[sbnd]C bonds and because of complex defects respectively. ZnO exhibits low PEC activity, but on nano-structuring in the form of ZP and ZS improves its light absorption capacity. Hydrothermal amination red shifts (∼25 nm)the absorption band at ∼ 425 nm. The N and C act as electron reservoirs in A-ZP and A-ZS photo-anodes and efficiently separate the photo-generated electron/hole pairs and restrain charge recombination to generate photo-reactive sites. Electrochemical impedance spectroscopy (EIS)revealed that A-ZP and A-ZS had low charge transfer resistance compared to their bare counterparts. This lead to considerably improved PEC performance. An unprecedented increase in IPCE values in A-ZP and A-ZS can be assigned to the decrease in band gap and thereby significant enhancement in photocurrent density. These result in to proper charge segregation and improved charge transportation. The maximum value of IPCE is 9.6% for A-ZS sample and it is also clear that ZP and ZS nanostructured film have higher IPCE values at ∼400 nm than traditional ZnO thin film. A-ZP and A-ZS based photo-anodes have exhibited enhanced PEC performance as evident from IPCE measurements and thus can be a prospective candidate for PEC and optoelectronic applications. © 2019 Hydrogen Energy Publications LLC

International Journal of Hydrogen Energy

Electrodeposition of highly porous ZnO nanostructures with hydrothermal amination for efficient photoelectrochemical activity

Plasmonic Ag−Au/ZnO nanorods (ZNRs) based photo-anodes were synthesized using a simple electrochemical route and were then evaluated for photoelectrochemical (PEC) activity. The amalgamation of Ag and Au nanoclusters broadens the UV-Vis light absorption in the range of 400 nm to 650 nm. Ag−Au/ZNRs photo-anodes had shown photocurrent density of ∼1.4 mA cm −2 , at a bias of 0.75 V/SCE, which is ∼3.1 times of bare ZNRs photo-anode. Bi-metallic Ag−Au/ZNRs based photo-anode shows the maximum photo-conversion efficiency of 0.77 % at 0.5 V/SCE, under one sun illumination. Formation of hot electrons in Ag−Au/ZNRs photo-anodes can be partly held responsible for the enhanced PEC activity. Au/Ag core/shell morphology evolves when a thin layer of Ag is loaded on Au nanoparticles. For an in-depth analysis on Ag−Au incorporated ZNRs based photo-anodes and its PEC activity, a detailed characterization was carried out using physico-chemical, spectral and microscopy techniques. The analysis shows that Au in direct contact with ZnO interacts mainly with oxygen vacancies present on surface of ZnO and Ag interacts with Au for an effective electron-hole segregation process at their interface and electron storage occurs in metal nanoparticles. The results suggest bi-metal incorporated ZNRs based photo-anodes can be a prospective candidate for PEC water splitting application. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Energy Technology

Ag−Au-Bimetal Incorporated ZnO-Nanorods Photo-Anodes for Efficient Photoelectrochemical Splitting of Water

5-Lipoxygenase (5-LOX) is a key enzyme involved in the biosynthesis of pro-inflammatory leukotrienes, leading to asthma. Developing potent 5-LOX inhibitors especially, natural product based ones, are highly attractive. Coumaperine, a natural product found in white pepper and its derivatives were herein developed as 5-LOX inhibitors. We have synthesized twenty four derivatives, characterized and evaluated their 5-LOX inhibition potential. Coumaperine derivatives substituted with multiple hydroxy and multiple methoxy groups exhibited best 5-LOX inhibition. CP-209, a catechol type dihydroxyl derivative and CP-262-F2, a vicinal trihydroxyl derivative exhibited, 82.7% and 82.5% inhibition of 5-LOX respectively at 20 µM. Their IC50 values are 2.1 ± 0.2 µM and 2.3 ± 0.2 µM respectively, and are comparable to zileuton, IC50 = 1.4 ± 0.2 µM. CP-155, a methylenedioxy derivative (a natural product) and CP-194, a 2,4,6-trimethoxy derivative showed 76.0% and 77.1% inhibition of 5-LOX respectively at 20 µM. Antioxidant study revealed that CP-209 and 262-F2 (at 20 µM) scavenged DPPH radical by 76.8% and 71.3% respectively. On the other hand, CP-155 and 194 showed very poor DPPH radical scavenging activity. Pseudo peroxidase assay confirmed that the mode of action of CP-209 and 262-F2 were by redox process, similar to zileuton, affecting the oxidation state of the metal ion in the enzyme. On the contrary, CP-155 and 194 probably act through some other mechanism which does not involve the disruption of the oxidation state of the metal in the enzyme. Molecular docking of CP-155 and 194 to the active site of 5-LOX and binding energy calculation suggested that they are non-competitive inhibitors. The In-Silico ADME/TOX analysis shows the active compounds (CP-155, 194, 209 and 262-F2) are with good drug likeliness and reduced toxicity compared to existing drug. These studies indicate that there is a great potential for coumaperine derivatives to be developed as anti-inflammatory drug.

GENERAL

VIT Unitversity

Department of Integrative Biology

School of Bio Sciences and Technology

Vellore Campus

Department of Control and Automation

School of Electrical Engineering

Department Of Biotechnology

Bioorganic and Medicinal Chemistry

Design, synthesis and identification of novel coumaperine derivatives for inhibition of human 5-LOX: Antioxidant, pseudoperoxidase and docking studies

Owing to the widespread occurrence and potential health effects, many treatment strategies have been developed across the world to remove the heavy metal contaminants in water. Developing affordable and sustainable nanoscale materials are the prime factors for the success of such treatment systems in the field. The present study explores the use of desiccant waste, exhausted after several cycles of dehumidification processes. The granulated composite desiccant is composed of boehmite nanoparticles reinforced with chitosan fibrils. The composite was synthesized via a simple and scalable one-pot sol-gel route at atmospheric pressure and room temperature. The desiccant was employed for dehumidification/regeneration cycles. The reuse potential of exhausted desiccant towards enhanced removal of metal ions was analyzed and demonstrated. After adsorption the nanocomposite was characterized to establish its chemical composition and structure. Batch and fixed-bed column adsorption experiments were performed to evaluate the removal efficiency of the nanocomposite and to assess the parameters that influence the adsorption process. The experimental evidences confirm the fast kinetics of adsorption/desorption and effective regeneration of the composite. The enhanced removal capacity, excellent reuse potential, high stable granules, eco-friendly synthesis approach makes the adsorbent an excellent candidate for the removal of wide range of heavy metals in water. © 2019 Elsevier Ltd

Journal of Environmental Management

Chitosan-boehmite desiccant composite as a promising adsorbent towards heavy metal removal

An apt and a futuristic nonlinear optical material sodium tetraborate pentahydrate (STBPH) was synthesized and grown by the technique of slow evaporation. The structural parameters of the crystal was confirmed by single crystal XRD revealed rhombohedral crystal system. Crystal's broad optical transparency was revealed by UV–Vis absorption spectrum. From the absorption spectrum, theoretical calculations were made to determine absorption coefficient, band gap, Urbach energy and reflectance. The functional groups were identified by FT-IR and FT-Raman spectra. Vicker's microhardness measurement disclosed that the grown crystal belongs to soft material category. Photoluminescence (PL) spectral study of STBPH indicated violet and blue emission peaks respectively at 343.06 nm and at 453.11 nm, 490.19 nm. Dielectric studies reveal the dielectric nature of the grown crystal. TGA-DTA studies showed that the crystal holds good thermal stability. The third order nonlinearities of STBPH was investigated by Z-scan technique manifest its suitability in nonlinear optical applications. © 2018 The Physical Society of the Republic of China (Taiwan)

Department of Digital Communications

School of Information Technology and Engineering

Physics

Chinese Journal of Physics

Synthesis, growth and third order nonlinear optical studies of a rhombohedral crystal: Sodium tetraborate pentahydrate

MgO nanoparticles (NPs) were successfully fabricated by a facile, inexpensive and green synthesis protocol using soluble starch as a green bio-template. The influence of calcination temperature on its textural properties and catalytic efficiency has been investigated in detail. The enhancement of MgO NPs crystallinity by increasing the calcination temperature is found from X-ray diffraction (XRD) and Transmission electron microscopy (TEM) analyses. N2-sorption studies and CO2-temperature programmed desorption (TPD) measurements revealed that the MgO NPs calcined at 500 °C have superior textural properties and strong surface basicity. X-ray photoelectron spectroscopy (XPS) analysis conferred that the MgO-500 NPs furnished the optimized surface Lewis sites, consequently outperforms better transesterification activity. The fabricated MgO-500 NPs exhibited an excellent catalytic activity towards the efficient conversion of glycerol to glycerol carbonate (GC) with more than 93% selectivity. The intelligibility of the adopted synthesis is eco-benign and wide utility as a solid base catalyst for several organic transformations. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Department of Design and Automation

School of Mechanical Engineering

ChemistrySelect

Optimizing the Surface Properties of MgO Nanoparticles Towards the Transesterification of Glycerol to Glycerol Carbonate

Composite photoanode comprising mesoporous microspheres with a smooth spherical morphology exhibiting high light scattering due to optical whispering gallery modes (WGMs) is used to fabricate whisperonic solar cell (WSC) devices. The photoanode is sensitized with CdS-CuInS 2 thin films (CdS-CIS-TF) of ∼5 nm thickness. CdS-CIS-TF-sensitized photoanodes exhibit strong coupling with WGM. These WSC devices show an average (η avg ) efficiency (η) of ≈3.2% in comparison with η avg ≈ 1.9% for the nanoparticulate-based photoanode. The observed efficiency is the highest for CdS-CIS-TF-sensitized solar cells made using I - /I 3 - electrolyte. This remarkable increase in η avg (∼60%) is attributed to increased photon absorption by the sensitizer films because of the presence of WGM scattering prevailing in smooth microspheres. Thus, WSC photoanode configuration is a promising approach to enhance the efficiency of TF-sensitized solar cells. © 2019 American Chemical Society.