Regular ArticleStructural Characterization of Nanocrystalline SnO2by X-Ray and Raman Spectroscopy
Abstract
Tin dioxide nanocrystalline powders were prepared by precipitation ofα-stannic acid followed by various thermal and chemical treatments. An original preparation via a colloidal solution step led to particles having a particular two-dimensional microstructure. The size of the crystallites was found to increase from 2 nm for as-prepared samples to 30 nm for samples annealed for 3.5 hr at 920°C. The compounds were characterized by X-ray diffraction, scanning electron microscopy (SEM), and infrared and micro-Raman spectroscopy. As reported in the literature, the Raman spectral signature was found to change drastically with the size of the particles. A new spectral feature centered at about 500 cm−1was found for compounds prepared via the colloidal step and having typical sizes smaller than 4.5 nm. The powder Raman spectra are interpreted in terms of volume modes and surface modes. Their frequency evolution with crystallite size is discussed in terms of tensile surface stresses.
References (17)
- D. Kohl
Sens. Actuators, B
(1990) - M. Ocana et al.
Spectrochim. Acta, Part A
(1991) - A. Dieguez et al.
Sens. Actuators, B
(1996) - H. Richter et al.
Solid State Commun.
(1981) - I. Campbell et al.
Solid State Commun.
(1986) - L. Saviot et al.
J. Non-Cryst. Solids
(1996) - K.L. Chopra et al.
Thin Solid Films
(1993) - R.S. Katiyar et al.
J. Phys. C: Solid State Phys.
(1971)
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Tailoring the optoelectronic properties of spray pyrolyzed SnO<inf>2</inf> thin films through cerium doping
2024, Optical MaterialsTin (IV) oxide (SnO2) thin films with varying cerium (Ce) concentrations were synthesized utilizing a cost-effective chemical spray pyrolysis process. The concentration of Ce was varied between 2 at% to 10 at% and thereby the consequences of the doping on the structural, morphological, elemental and optical properties of the SnO2 thin film was analysed through variety of characterization techniques. X-ray diffraction (XRD) studies revealed the rutile tetragonal structure of the prepared thin films having polycrystalline nature. The formation of SnO2 was further supported by Raman spectroscopic results. Further, a decrement in the crystallite size with increase in the Ce-doping concentration was observed. Scanning electron microscopic (SEM) results and energy dispersive spectroscopy (EDS) measurements corroborates that the films were uniform and nearly stoichiometric. Optical properties of all the thin films were analysed using absorption spectra. Optical bandgap was found to vary from 3.31eV to 2.99eV with cerium doping which demonstrates the effective bandgap tailoring potential of cerium. The lowest bandgap of 2.99eV was obtained for 6 at% Ce doped SnO2 thin film. Further, density functional theory (DFT) calculations were carried out to validate the structural stability along with electronic band gap and optical absorption spectra calculations for all samples. Combined theoretical investigations are well matched with experimental results. The highest emission intensity in photoluminescence spectra was found for 6 at% Ce doped SnO2 thin film. The optical studies reveals that 6 at% Ce doped SnO2 thin film has the most desirable properties that can be utilized for a varieties of optoelectronic applications.
One of the solutions for the growing problem of water purification is photocatalytic degradation of the pollutants. Semiconductor nanoparticles are widely under study as a promising photocatalyst for this purpose. However, there is still lack of understanding of the relation between properties of nanoparticles, in their turn related with synthesis conditions, and photocatalytic efficiency, as well as of the other factors influencing the process.
For the first time, a possibility to regulate photocatalytic activity of SnO2 nanoparticles under UV light via regulation of structural parameters is shown. A method for obtaining spherical nanoparticles with different parameters was developed. Obtained nanoparticles were fully characterized. Special attention was paid to the study of oxygen vacancies. With the help of quantum computational methods, it was shown, that the concentration of vacancies is around 1 per 32 tin atoms. Obtained data on oxygen vacancies were further used for the evaluation of pollutant-nanoparticle surface interaction to get closer to the calculations of real systems.
On the example of methylene blue, it was shown that the greater is the amount of oxygen vacancies and the lower the amount of defects, the higher photocatalytic activity. The obtained dependence is confirmed by the fact that the photoresponse increases with a decrease of amount of defects in the sample. Degradation kinetics of sulfonamides mixture was studied, and its dependence on active complex formation was shown based on the quantum chemical calculation data. Degradation of antibiotics in water from Neva River reached more than 95% in 35 min, which indicates that developed photocatalyst efficiency is not affected by pollutants contained in open water in the centre of the metropolis. It was shown, that the use of nanoparticles allows to speed up the process of bacteria destruction under UV light, which indicates the antibacterial activity of obtained nanoparticles.
Size- and temperature-dependent optical, and electron field emission characteristics on SnO<inf>2</inf> nanocrystals
2024, Physica B: Condensed MatterSize-dependent SnO2 nanocrystals (NCs)) were synthesized using a co-precipitation technique. The particle size was varied by annealing the as-prepared SnO2 NCs with the estimated size of 2.3 nm at different temperatures. The particle size obtained was 4.7, 9.0, 15.4, 19.6, and 48.0 nm at annealing temperatures of 400, 600, 800, 1000, and 1200 °C, respectively. The XRD data revealed the tetragonal rutile structured for all SnO2 NCs. The temperature-dependent photoluminescence (PL) studies showed that the sub-bridging oxygen vacancy contributed dominantly compared to the in-plane and bridging oxygen vacancies at 5K. The function of nanocrystals’ size on field emission properties is also reported. The current density was high (1.9 μA/cm2) with modest the turn-on field (8.4 V/μm) for as-prepared SnO2 QDs with the lowest size (2.3 nm) compared to the high temperature annealed SnO2 nanocrystals.
Investigation on Sb-doped SnO<inf>2</inf> as an efficient sensor for the detection of formaldehyde
2023, Materials Today CommunicationsThe applicability of antimony-doped tin dioxide (Sb-doped SnO2) as a very precise sensor for detecting formaldehyde (HCHO) gas is investigated in this study. The sol-gel method was used to prepare pure SnO2 and Sb-doped SnO2 nanostructures, which resulted in better structural and morphological properties. The prepared samples were analyzed using several characterization techniques, including X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS). A structural investigation indicated the presence of a tetragonal SnO2 phase with a clear preference for the (110) orientation. Furthermore, the crystallite size reduced as the quantity of Sb doping rose. According to FE-SEM analysis, both the undoped (SnO2) and Sb-doped SnO2 samples had polyhedral structures. FTIR analysis verified the presence of organic functional groups in the prepared powder samples. The optical band gap (Eg) values decreased with an increasing concentration of Sb doping in the SnO2 nanostructures. XPS was used to determine the chemical elements of the prepared powder samples. In the gas sensing study, those based on 8 wt% Sb-doped SnO2 (referred to as ATO-8) outperformed the others. At room temperature, the ATO-8 sample demonstrated stronger sensor response, faster response and recovery durations (98 s/74 s), and linear behavior. These enhancements can be attributable to an increase in adsorbed oxygen species caused by Sb doping, highlighting ATO-8's potential as a substance for detecting HCHO. This study emphasizes the potential of ATO-8 as a significant resource for practical use in the detection of HCHO, with benefits such as improved indoor air quality, increased industrial safety, and advancements in environmental monitoring.
Fabrication of 1.6 V asymmetric supercapacitor in an aqueous electrolyte using a CuO-SnO<inf>2</inf> composite and activated carbon electrodes
2023, Materials Today CommunicationsThis work reported the successful preparation of the CuO and SnO2 by the facile co-precipitation method for energy storage applications, especially for supercapacitors (SCs). Subsequently, a CuO-SnO2 composite was further prepared to enhance the composites electrochemical properties. The detailed research survey showed that the combination of these two typical pseudocapacitive metal oxides reasonably enhances their structural integrity, and electronic conductivity, resulting in an optimized electrochemical property. According to the electrochemical studies, an exceptional 246 C/g capacitance is revealed by the CuO-SnO2 composite than 162 C/g (SnO2) and 89 C/g (CuO) exhibiting a synergistic effect in the composite between Sn and Cu-based oxides. A high specific energy of 35.3 Wh/kg with a maximal specific power of 4000 W/kg was obtained by assembling a hybrid asymmetric SC (HASC) with activated carbon (AC), symbolized as CuO-SnO2||AC, that yields a high voltage of 1.6 V. Nevertheless, 88.7 % retention in capacitance was revealed after 5000 cycles taken at a the discharge current of 15 A/g, proving the great durability of the CuO-SnO2||AC HASC. From all these exciting findings, SnO2 composite with CuO can be a potential and a viable choice for SCs and other energy storage gadgets.
Schottky junction based solar cell behavior of trichome hierarchical SnO<inf>2</inf> nano-structures
2023, Optical MaterialsHydrothermally grown SnO2 hierarchical trichome nano-flowers (T-NFLs) have been examined for their device performance compared to nano-flakes (NFs), in part to meet the growing need for metal-oxide based solar cells. The structural analyses reveal superior lattice strain and free energy in the tetragonal phase of the T-NFLs over NFs. The band gap widening and oxygen defect-dominated luminescence in the visible range are observed from photoluminescence measurements. Compared to NFs, the Schottky current-voltage characteristics of the T-NFLs show improved Schottky barrier height (0.82 eV) with an ideality factor of 3.52 under dark and better solar cell properties with a conversion efficiency of 1.78 ± 0.03% under 1 sun illumination. The observed high open-circuit voltage of 1.56 V resulted from the decrement rate of carrier recombination, making the transparent metal oxide nano-material SnO2 T-NFLs suitable for solar cells and fast electronic applications.
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