Composite & Ceramic Materials
Vithal Muga; Vaishnavi Kammara; Venkataswamy Perala; Manasa Sunku; Ramaswamy Kadari; Hima Bindu Gaddameedi; Sudhakar Reddy Chandiri
Abstract
Doping of cations into wide bandgap semiconductors is an effective method of increasing photocatalytic activity. This work aims to find out how dopant ions like Ag+, Cu2+ and Sn2+ affect the structural, optical and photocatalytic properties of Li2GeTeO6. The parent Li2GeTeO6 (LGTO) was synthesized by ...
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Doping of cations into wide bandgap semiconductors is an effective method of increasing photocatalytic activity. This work aims to find out how dopant ions like Ag+, Cu2+ and Sn2+ affect the structural, optical and photocatalytic properties of Li2GeTeO6. The parent Li2GeTeO6 (LGTO) was synthesized by conventional solid-state method, whereas the Ag+, Cu2+ and Sn2+-doped Li2GeTeO6 were prepared by a simplistic ion-exchange method. Techniques such as XRD, FT-IR, SEM-EDS, N2 adsorption-desorption analysis, UV-Vis DRS, XPS, and PL were employed to examine the physico-chemical properties of the as-prepared materials and their photocatalytic activities on the degradation of methyl violet (MV) under visible light irradiation. The acquired photocatalytic activity results revealed that all doped samples displayed enhanced photocatalytic performance compared with parent LGTO. The Ag-LGTO had the best photocatalytic activity for MV degradation, with 68.6% degradation efficiency in 180 min of irradiation. Scavenging experiments were carried out to determine the role of various active species generated on the surface of Ag-LGTO during the photocatalytic degradation of MV. The reusability and stability of Ag-LGTO up to five cycles against MV degradation were also investigated. A photocatalytic mechanism for MV degradation over the Ag-LGTO sample was also proposed based on the findings described above.
Aruna K Kunhiraman; Bradha Madhavan
Abstract
Facile solvothermal route was adopted for the synthesis of Co2xMo1-xS2 with x = 0, 0.05 and 0.1. Higher HER activity was exhibited by x = 0.1 in Co doped MoS2, with a current density -140 mAcm -2 at an overpotential of -100 mV. At lower overpotential both the compositions exhibited almost same activity, ...
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Facile solvothermal route was adopted for the synthesis of Co2xMo1-xS2 with x = 0, 0.05 and 0.1. Higher HER activity was exhibited by x = 0.1 in Co doped MoS2, with a current density -140 mAcm -2 at an overpotential of -100 mV. At lower overpotential both the compositions exhibited almost same activity, whereas with the increase in the overpotential and under continuous electrochemical operation, the active sites of composition with x = 0.1 was triggered and it was reflected in its HER activity.
Khalid Sultan; Rubiya Samad; Feroz A. Najar; Shohaib Abass; Saima Jahan; Mudasir Rashid Rather; M. Ikram
Abstract
Polycrystalline bulk samples of chemical composition La1-xSrxVO4 (x = 0.0, 0.1, 0.3, 0.5) were prepared by solid state reaction method. The Morphology and structure wascharacterised by Scanning Electronic microscopy and powder X-ray diffraction respectively. All the prepared material were single-phase ...
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Polycrystalline bulk samples of chemical composition La1-xSrxVO4 (x = 0.0, 0.1, 0.3, 0.5) were prepared by solid state reaction method. The Morphology and structure wascharacterised by Scanning Electronic microscopy and powder X-ray diffraction respectively. All the prepared material were single-phase and co-doped ions were successfully incorporated in LaVO4 lattice. The EDAX spectrum shows that the percentage composition of given elements in the proposed formula was in good agreement with the corresponding values determined experimentally. The Raman spectra of LaVO4 reflect the VO4 type structure that consists of four different V–O bands. The prominent Raman band at about 860 cm -1 can be assigned to the symmetric V–O stretching mode while the weak Raman band at 792 cm -1 is assigned to antisymmetric V–O stretching mode. With increase in Sr doping, optical band gap was found to decrease resulting in increase in conductivity. The dielectric constant as well as dielectric loss shows a relaxor type of behaviour for higher doping concentration which can be attributed to the chemical pressure induced in LaVO4 with the doping of Sr ions. The studies performed on ac conductivity identifies that the conduction mechanism follows the charge hopping between localised states and follow the small polaron conduction.
Mannepalli Sudheera; Perala Venkataswamy; Gundeboina Ravi; Kadari Ramaswamy; Nalluri Chitti Babu; Muga Vithal
Abstract
Anion doping is one of the efficient ways to tailor the bandgap of photocatalysts for the treatment of polluted water. The present work describes the improved photocatalytic activity of defect pyrochlore, KTaTeO6 (KTTO), upon nitrogen doping, towards the degradation of methylene blue under visible light ...
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Anion doping is one of the efficient ways to tailor the bandgap of photocatalysts for the treatment of polluted water. The present work describes the improved photocatalytic activity of defect pyrochlore, KTaTeO6 (KTTO), upon nitrogen doping, towards the degradation of methylene blue under visible light irradiation. The parent KTaTeO6 was synthesized by solid-state method. The N-doped KTaTeO6 (N-KTTO) was prepared by nitridation method using NH3. Techniques such as the XRD, N2 adsorption-desorption, FE-SEM/EDX/EDS elemental mapping, TEM-HRTEM, UV-Vis DRS, XPS, Raman, and PL were employed to characterize the physicochemical properties of photocatalysts. The N-doping in KTTO has resulted in enlarged surface area, narrowed the bandgap, and reduced the recombination of photogenerated electron-hole pairs, leading to enhanced photocatalytic activity compared to parent KTTO. The active species trapping experiments were conducted to elucidate the mechanism of photodegradation. The N-KTTO is chemically stable and can be used at least up to five cycles.
Jyoti Tyagi; Lekha Sharma; Rita Kakkar
Abstract
Two different models, ovalene (C32H14) and circumcoronene (C54H18) and their respective doped models (C31XH14, C53XH18 where X = B, Al, N, P, Fe, Ni and Pt) have been considered for DFT calculations at the GGA-PBE/DNP level. The two models are compared on the basis of various calculated structural parameters ...
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Two different models, ovalene (C32H14) and circumcoronene (C54H18) and their respective doped models (C31XH14, C53XH18 where X = B, Al, N, P, Fe, Ni and Pt) have been considered for DFT calculations at the GGA-PBE/DNP level. The two models are compared on the basis of various calculated structural parameters and electronic properties. Electronic density of states (DOS) spectra are also plotted to see the changes in the electronic properties on increasing the size. No major changes are observed in the structural and electronic properties as one move from the smaller model to the higher one. It is found that doping maintains the planarity of the surface but induces comparatively large changes in the bond lengths around the doped atom, weakening the bonds. Copyright © VBRI Press.
Mpho W. Maswanganye; Koena E. Rammutla; Thuto E. Mosuang; Bonex W. Mwakikunga; Sone T. Bertrand; Malik Maaza
Abstract
Co and In co-doped nanopowders of ZnO as well as In and Co singly doped ZnO were successfully prepared using sol-gel method. The synthesized samples were characterized using x-ray diffraction (XRD), UV-vis spectroscopy (UV-vis), Raman spectroscopy (RS), Transmission Electron Microscopy (TEM) and Energy ...
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Co and In co-doped nanopowders of ZnO as well as In and Co singly doped ZnO were successfully prepared using sol-gel method. The synthesized samples were characterized using x-ray diffraction (XRD), UV-vis spectroscopy (UV-vis), Raman spectroscopy (RS), Transmission Electron Microscopy (TEM) and Energy Dispersive Spectroscopy (EDS). The effects of In and Co co-doping on the structural and optical properties were investigated. XRD results showed no peaks associated with In 3+ or Co 2+ ions indicating that In 3+ and Co 2+ ions substituted for Zn 2+ ions in the ZnO wurtzite structure, this was corroborated by the EDS results. Doping ZnO nanoparticles with In and Co significantly reduced the grain sizes whereas the lattice parameters were not significantly affected. TEM results confirmed that the nanoparticles were spherically shaped. Raman spectroscopy also confirmed that the ZnO nanoparticles were of a wurtzite hexagonal structure. Single doping reduced the energy band gaps and co-doping reduced them even further.
Tarun Kumar Kundu; Debolina Misra
Abstract
Density Functional Theory (DFT) is employed to study the various optical properties of pseudo-cubic LaNiO3. As LaNiO3 is a strongly correlated material, conventional DFT like LDA or GGA and even GW approximation fail to describe, we have examined the optical spectra of this compound using GGA(PBE)+U ...
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Density Functional Theory (DFT) is employed to study the various optical properties of pseudo-cubic LaNiO3. As LaNiO3 is a strongly correlated material, conventional DFT like LDA or GGA and even GW approximation fail to describe, we have examined the optical spectra of this compound using GGA(PBE)+U approach. The advantage of incorporating Hubbard U in this approach is to take the strong electronic correlation in the system into account. The optical spectra of this compound are found to be consisted of the Drude peak and some high energy peaks. While the Drude peak reflects the dominant free carrier contributions at the low energy region, the high energy peaks originate from the inter-band transitions within the system. We have also studied the remarkable changes in the optical properties in Fe doped LaNiO3 (LaNi1-xFexO3), in order to probe related properties, corresponding to their applications in solid-oxide fuel cells. Our calculations have revealed that even 25% of Fe doping is adequate to trigger a first order metal to insulator transition in LaNiO3. The optical spectra of LaNi1-xFexO3 compounds are calculated using the hybrid functional HSE and the doping-induced metal to insulator transition in LaNiO3 is attributed to the altered crystal environment and electronic configuration of the compound.
Sibel Gurakar; Tulay Serin; Necmi Serin
Abstract
The effect of Cu, Al and In doping on the microstructural and the electrical properties of the SnO2 films were studied. The undoped, Cu, Al and In (2 at. %) doped SnO2 films were deposited on the glass substrate by spray pyrolysis from 0.8 M SnCl2–ethanol solution at substrate temperature 400 °C. ...
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The effect of Cu, Al and In doping on the microstructural and the electrical properties of the SnO2 films were studied. The undoped, Cu, Al and In (2 at. %) doped SnO2 films were deposited on the glass substrate by spray pyrolysis from 0.8 M SnCl2–ethanol solution at substrate temperature 400 °C. The microstructural properties of films were investigated by X-ray diffraction (XRD) method. It was determined that the films formed at polycrystalline structure in tetragonal phase and structure was not changed by dopant species. The lattice parameters (a), (c) and crystallite size (D) were determined and obtained in the range of 4.90-4.92 Å, 3.26-3.31 Å and 34-167 Å, respectively. The optical transmittance of thin films was measured and the optical band gap Eg values of the films were obtained in the range of 3.96-4.00 eV, using the Tauc relation. The electrical transport properties of undoped, Cu, Al and In-doped SnO2 films were investigated by means of conductivity measurements in a temperature range of 120-400 K. The electrical transport mechanism of the undoped, Cu, Al and In-doped SnO2 films was determined by means of the tunneling model through the back-to-back Schottky barrier and the thermionic field emission model in the temperature range of 120-300 K and 300-400 K, respectively.
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