Search query: Raman studies of semiconducting oxide nanobelts

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abstract: Crystalline nanobelts of ZnO and SnO2 were prepared from a thermal evaporation of oxide powders inside an alumina tube in the absence of catalysts. Typical dimensions of the nanobelt samples ranged from approximately 10 to 100 microns in length, 30 to 300 nm in width, and 6 to 30 nm in thickness. Room temperature Raman spectra were obtained on pressed mats of nanobelt samples and compared with the corresponding spectra of the starting oxide powders and bulk materials. Collectively, our Raman data indicated that the as prepared nanobelt samples used in this study were oxygen deficient. Upon annealing at 900 degrees C in flowing oxygen for 1 h, the nanobelt samples exhibited Raman features that corresponded to those expected in respective bulk semiconducting oxides. The dimensions of the nanobelts were a bit too large to expect significant quantum size effects on the phonon structure similar to those observed in carbon nanotubes and short period semiconductor superlattices.
author_names: K Mcguire

Zhengwei Pan

Zhong Lin Wang

Daniel E Milkie

Jose Luis Menendez

Apparao M Rao
title: Raman studies of semiconducting oxide nanobelts.
venue: Journal of nanoscience and nanotechnology
year: 2002

abstract: Abstract In this study, we report a synthesis of nanobelts form zinc (Zn) doped molybdenum oxide (MoO 3 with different weight percentages (2% 3.3% 4% and 5% The synthesized nanobelts grain size is of 45 nm. The preparation process and characterization techniques are presented in detail. Structural properties are studied by using the X ray diffraction technique, scanning electron microscopy and transmission electron microscopy. The optical properties are investigated by using the Fourier transform infrared spectroscopy, UV Vis reflectance spectra analysis, Raman spectroscopy, and fluorescence techniques. It was founded that Zn doping concentration highly influences the crystallographic structure where it passes from the insertion to the substitution alloys. The band gap decreases from 2.96 eV to 2.83 eV. The good structural and optical properties were obtained for the 5%Zn. The photocatalytic effect of the materials was studied for the pure and 5%Zn doped MoO 3 and it was denoted that Zn doping influences it highly.
author_names: Amal L Al-Otaibi

Taher Ghrib

Mody Alqahtani

M A Alharbi

Ridha Hamdi

Imen Massoudi
title: Structural, optical and photocatalytic studies of Zn doped MoO3 nanobelts
venue: Chemical Physics
year: 2019

author_names: Aurangzeb Khan

Saima Khan

W M Jadwisienczak

Martin E Kordesch
title: Raman Spectroscopic Studies of Monoclinic Gallium Oxide b Ga 2 O 3 Nanostructures: A Comparison Between Nanowires and Nanobelts
year: 2009

author_names: Aurangzeb Khan

Saima Khan

W M Jadwisienczak

Martin E Kordesch
title: Raman spectroscopic studies of monoclinic Gallium Oxide \beta Ga$_{2}$O$_{3} Nanostructures: A comparison between nanowires vs. nanobelts
year: 2009

abstract: The structure, conductivity, and sensor properties of nanostructured semiconducting composites consisting of binary mixtures of In 2 O 3 with SnO 2 ZnO and CeO 2 additives were investigated. The study considered the dependence of these properties on composition of materials and temperature. Such binary composites have been found to be promising for highly sensitive conductometric sensors for H 2 and CO. To prepare the nanocomposites, In 2 O 3 crystals of 70 nm average size were kept for long duration in aqueous solutions of Sn, Zn, and Ce salts. The resulting slurry was subjected to heat treatment at 300 degC for 4 5 hrs in order to decompose the salts into the corresponding oxides which were deposited on the surface of the In 2 O 3 nanocrystals. The structure of the composites was analyzed by Raman spectroscopy, transmission electron spectroscopy (TEM) and X ray spectroscopy. It is shown that in the synthesized In 2 O 3 SnO 2 In 2 O 3 ZnO, and In 2 O 3 CeO 2 nanocomposite systems, the value of SnO 2 CeO2, and ZnO nanocluster size is 8 9 nm. The resistance and sensor properties of the nanocomposites changes dramatically for different concentrations of components in mixtures. A kinetic model of sensor processes in rich and poor by electrons nanostructured semiconductors, which allows us to a quantitative description of the sensor effect including dependence of sensor sensitivity on temperature is presented. This consideration is based on the previously developed model of electron structure of semiconductor nanoparticle. Concurrently, experiments are performed to quantify the sensor response by corresponding nanostructured thin film as a function of temperature and hydrogen concentration upon addition of hydrogen gas to the gas medium. The measured response is described well by the theoretical model developed in this work.
author_names: leonid trakh
title: Sensor properties of In2O3 based semiconducting binary metal oxide nanocomposites L.I. Trakhtenberg, G.N. Gerasimov, V.F. Gromov, M.I. Ikim, O.J. Ilegbusi, M.A. Kozhushner, V.L. Bodneva, V.S. Posvyanskii
year: 2018

abstract: Semiconducting oxide nanoparticles have proven to be excellent in detecting extremely low concentrations of molecules through surface enhanced Raman scattering (SERS) effects. While the enhancement of the Raman activities arises from a large increase in polarizability due to charge transfer from the molecule to the semiconducting nanoparticle, little is known about how the oxide composition, nanoparticle size, solvent, or pH affects the observed Raman activities. In the current study, we examine these effects by carrying out extensive computational investigations of semiconducting TiO2, SnO2 and Fe2O3 nanoparticles and their complexes with both catechol and dopamine. An increase in the size of the oxide cluster or a decrease in the pH of the system under observation leads to enhanced Raman activities; the variation of the activities in different solvents is very much dependent on the nature of the vibrational modes. The marked increase in the Raman activities of molecules adsorbed on SnO2 or Fe2O3 over th.
author_names: Pilarisetty Tarakeshwar

Daniel Finkelstein-Shapiro

Sarah J Hurst

Tijana Rajh

Vladimiro Mujica
title: Surface Enhanced Raman Scattering on Semiconducting Oxide Nanoparticles: Oxide Nature, Size, Solvent, and pH Effects
year: 2011

abstract: In this study, F doped vanadium oxide thin films with doping levels up to 60 at were prepared by spray pyrolysis method on glass substrates. To measure the electrochemical properties, some films were deposited on fluorine tin oxide coated glass substrates. The effect of F doping on the structural, electrical, optical and electrochemical properties of vanadium oxide samples was investigated. The X ray diffractographs analysis has shown that all the samples grow in tetragonal b V2O5 phase structure with the preferred orientation of [200] The intensity of (200) peak belonging to b V2O5 phase was strongest in the undoped vanadium oxide film. The scanning electron microscopy images show that the samples have nanorod and nanobelt shaped structure. The size of the nanobelts in the F doped vanadium oxide films is smaller than that in the pure sample and the width of the nanobelts increases from 30 to 70 nm with F concentration. With increasing F doping level from 10 to 60 at the resistivity, the transparency and the optical band gap decrease from 111 to 20 O cm, 70 to 50% and 2.4 to 2.36 eV, respectively. The cyclic voltammogram (CV) results show that the undoped sample has the most extensive CV and by increasing F doping level from 20 to 60 at the area of the CV is expanded. The anodic and cathodic peaks in F doped samples are stronger.
author_names: Maliheh Mousavi

Gh H Khorrami

Ahmad Kompany

Sh Tabatabai Yazdi
title: Structural, optical and electrochemical properties of F doped vanadium oxide transparent semiconducting thin films
year: 2017

abstract: Abstract In this study, we report the fabrication of high performance gas sensor based on a heterojunction structure in which Fe2O3 nanoparticles were used to decorate MoO3 nanobelts. The pure MoO3 nanobelts exhibited a response to 100 parts per million (ppm) of xylene (ratio of resistance to air and gas 9.08) with no obviously lower cross responses to 100 ppm of ethanol, acetone, benzene, toluene, methanol and butanol. Compared with pristine MoO3 nanobelts, Fe2O3 nanoparticles decorated nanobelts demonstrated about 2 4 times higher response toward xylene. The enhanced sensing properties of Fe2O3 nanoparticles decorated MoO3 heterostructured nanobelts can be attributed to the formation of heterojunction between Fe2O3 and MoO3. These results, combined with other reported literature, indicate that controlled engineering of surface loading/decorating is an effective strategy for designing highly sensitive and selective semiconducting metal oxide based gas sensors.
author_names: Fengdong Qu

Xinxin Zhou

Shendan Zhang

Chunjie Jiang

Shengping Ruan

Minghui Yang
title: Fe2O3 nanoparticles decorated MoO3 nanobelts for enhanced chemiresistive gas sensing
venue: Journal of Alloys and Compounds
year: 2019

abstract: The stimuli responsive behaviour of charge transfer donor acceptor metal organic frameworks (MOFs) remains an understudied phenomenon which may have applications in tuneable electronic materials. We now report the modification of donor acceptor charge transfer characteristics in a semiconducting tetrathiafulvalene naphthalene diimide based MOF under applied electrochemical bias and pressure. We employ a facile solid state in situ Raman spectroelectrochemical technique, applied for the first time in the characterisation of electroactive MOFs, to monitor the formation of a new complex TTFTC. DPNI from a largely neutral system, upon electrochemical oxidation of the framework. In situ pressure dependent Raman spectroscopy and powder X ray diffraction experiments performed in a diamond anvil cell revealed blue shifts in the donor and acceptor vibrational modes in addition to contractions in the unit cell which are indicative of bond shortening. This study demonstrates the utility of in situ Raman spectroscopic techniques in the characterisation of redox active MOFs and the elucidation of their electronic behaviours.
author_names: Pavel M Usov

Chanel F Leong

Bun Chan

Mikihiro Hayashi

Hiroshi Kitagawa

Joshua J Sutton

Keith C Gordon

Idan Hod

Omar K Farha

Joseph T Hupp

Matthew A Addicoat

Agnieszka Beata Kuc

Thomas Heine

Deanna M D'Alessandro
title: Probing charge transfer characteristics in a donor acceptor metal organic framework by Raman spectroelectrochemistry and pressure dependence studies.
venue: Physical chemistry chemical physics PCCP
year: 2018

abstract: Raman scattering enhancement was observed in systems where different metal oxide semiconductors (TiO2, Fe2O3, ZrO2 and CeO2) were modified with enediol ligands. The intensity of Raman scattering was dependent on laser frequency and correlated with the extinction coefficient of the charge transfer complex of the enediol ligands and nanoparticles. The intensity and frequency of the Raman bands was found to depend on the chemical composition of the enediol ligand and the chemical composition (and crystallinity) of the nanoparticles. The intensity of the Raman signal depends on the number of surface binding sites, electron density of the ligands and their dipole moment. We also found that Raman scattering is observed for the bioconjugated system, where a peptide is linked to the surface of the particle through a catechol linker. These studies are important since these bioconjugates can be used to form the basis of Raman based, in vitro and importantly in vivo biodetection, cell labeling and imaging, and nanotherapeutic strategies.
author_names: Sarah J Hurst

H Christopher Fry

David J Gosztola

Daniel Finkelstein-Shapiro

Vladimiro Mujica

Tijana Rajh
title: Mechanistic studies into the Raman enhancement of enediol semiconducting nanoparticle conjugates and their use in biological applications
venue: NanoScience Engineering
year: 2010