IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
Not a member yet
4657 research outputs found
Sort by
Band Edge Engineering of BiOX/CuFe2O4 Heterostructures for Efficient Water Splitting
No full textLayered bismuth oxyhalides (BiOX, X = Cl, Br, and I) are promising visible light-responsive photocatalysts but suffer from inadequate electron transportation from the bulk to the surface. Construction of heterostructures has been considered as a convenient approach to improve the spatial charge carrier separation and enhance the efficiencies of the surface-reactive charges for catalysis. Here, a series of heterostructures has been successfully designed for n-type bismuth oxyhalides and p-type spinel ferrites CuFe2O4 (CFO) by a ladle and generalized protocol via the hydrothermal method followed by the co-precipitation method. The heterostructure introduces built-in electric field at the interface that facilitates vectorial charge transfer, which demonstrated significantly improved visible light-driven photocatalytic activity toward H-2 generation without using any noble metal co-catalyst. A conventional type-I and type-II charge transfer mechanism has been followed for BiOBr/CFO and BiOI/CFO heterostructures, respectively, which may effectively lower charge transfer resistance compared to that for bare BiOBr and BiOI, suggesting facile charge transfer. Remarkably, a direct Z-scheme BiOCI/CFO heterostructure has been formed between BiOCl and CFO with an intimate interfacial contact, which demonstrated 5.7 times higher H-2 generation activity than pure BiOCl and two fold improved catalytic efficiency compared to type-II BiOI/CFO heterostructures under visible light. Very low resistance in electrochemical impedance spectra confirmed the superiority of the direct Z-scheme in promoting the charge separation and transfer and increase in carrier density. Moreover, the optimal space charge layer width and the redox potentials have been achieved for BiOCI/CFO through the engineering of band edge potentials, which reduces the fast recombination rate. This work offers a paradigm for the design of highly engineered BiOX-based heterostructures with tuned band structures for efficient photocatalytic water splitting
Hierarchical Bi2WO6/BiFeWO6 n-n heterojunction as an efficient photocatalyst for water splitting under visible light
No full textA hierarchical Bi2WO6/BiFeWO6 architectures were synthesized by a facile and low-cost hydrothermal approach using Bi2WO6 flower structure as an efficient backbone for the growth of layered BiFeWO6 sheets. The conduction band offset and bandgap of flower like Bi2WO6 were tailored strategically as active photocatalyst under visible light and suitable for water reduction. By developing n-n heterojunction between Bi2WO6 and BiFeWO6, the active surface area as well as number of free charge carriers have been enhanced which may boost the catalytic redox reactions. The physicochemical properties of the heterojunction was characterized to investigate the phase, morphology, thermal stability, light absorption and oxidation states of the elements. The photocatalytic activity of Bi2WO6/BiFeWO6 heterojunction was investigated through H-2 generation via water splitting under visible light, where four-fold enhanced activity achieved for heterojunction compared to bare Bi2WO6. Further, photoelectrochemical properties were studied to determine the band edge potentials and illustrate the enhanced photoresponse for heterojunction. The Bi2WO6/BiFeWO6 heterojunction showed lower charge transfer resistance compared to Bi2WO6, owing to efficient charge separation at electrode-electrolyte interface. The synergistic effect of high surface area, lower recombination rate and the suitable band edge potentials led to high catalytic activity, good cycling stability and superior photoelectrochemical response of heterojunction. This work provide insight into the synergistic effect of hierarchical n-n heterojunction and opens up an avenue for rational design of photocatalyst for water splitting and H-2 generation. (C) 2022 Published by Elsevier B.V
Multimode Mamyshev oscillator
No full textWe present a spatiotemporally mode-locked Mamyshev oscillator. A wide variety of multimode mode-locked states, with varying degrees of spatiotemporal coupling, are observed. We find that some control of the modal content of the output beam is possible through the cavity design. Comparison of simulations with experiments indicates that spatiotemporal mode locking (STML) is enabled by nonlinear intermodal interactions and spatial filtering, along with the Mamyshev mechanism. This work represents a first, to the best of our knowledge, exploration of STML in an oscillator with a Mamyshev saturable absorber. (C) 2021 Optica Publishing Grou
Structure and Conductivity Correlation in NASICON Based Na3Al2P3O12 Glass: Effect of Na2SO4
No full textIdentifying the factors influencing the movement of sodium cations (Na+) in glasses accelerates the possible options of glass-based solid electrolyte materials for their applications as a promising electrolyte material in sodium-ion batteries. Nevertheless, due to the poor correlation between the structure and conductivity in glass materials, identifying the factors governing the conductivity still exists as a challenging task. Herein, we have investigated the DC-conductivity variations by correlating the structure and conductivity in sodium superionic conductor (NASICON) based Na3Al2P3O12 (NAP) glass (mol%: 37.5 P2O5-25.0 Al2O3-37.5 Na2O) due to the successive substitution of Na2SO4 for Al2O3. Structural variations have been identified using the Raman and magic-angle spinning nuclear magnetic resonance (MAS-NMR) (for P-31, Na-23, and Al-27 nuclei) and conductivity measurements have been done using the impedance spectroscopy. From the ac-conductivity spectra, the correlations between mean square displacement (MSD) and dc-conductivity and between the Na+ concentration and dc-conductivity have also been evaluated. Raman spectra reveal that the increase in the Na2SO4 concentration increases the number of isolated SO42- sulfate groups that are charge compensated by the Na+ cations in the NAP glass. MAS-NMR spectra reveal that the increase in Na2SO4 concentration increases the concentration of non-bridging oxygens and further neither S-O-P nor S-O-Al bonds are formed. Impedance spectroscopy reveals that, at 373 K, the DC conductivity of the NAP glass increases with increasing the Na2SO4 up to 7.5 mol% and then decreases with the further increase. In the present study, we have shown that the mobility of sodium cations played a significant role in enhancing the ionic-conductivity. Further, we have shown that inter-ionic Coulombic interactions and the structural modification with the formation of SO42- units significantly influence the critical hopping length of the sodium cations and consequently the mobility and the ionic conductivity. The present study clearly indicates that, based on the compositions, glass materials can also be treated as strong-electrolyte materials
Development of superhydrophobic coating from biowaste and natural wax
No full textNowadays, superhydrophobic coatings (SHCs) fabricated from eco-friendly and sustainable materials are high in demand as they do not contribute to additional carbon footprint. In the present work, biowaste eggshell powder and food grade natural beeswax based SHC with static water contact angle, SCA ti 156 degrees, and sliding angle, SA 150 degrees) and also prevents adherence of the liquids. The fabricated coating also exhibits significant stability towards handling. In addition, the SHC inhibits protein adsorption on its surface. Thus, the fabricated eco-friendly SHC can be used as a potential liquid anti-adhesive food packaging coating to prevent wastage of common drinks consumed in our daily life.Copyright (c) 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Smart and Sustainable Developments in Materials, Manufacturing and Energy Engineerin
Development of La-impregnated TiO2 based ethanol sensors for next generation automobile application
No full textBio-fuel, a blend of ethanol (similar to 10 to 85%) and gasoline with various compositions, is one of the promising next generation energy sources in automobile industries, especially in flex-fuel vehicles. Here, the detection of ethanol content is essential for adjusting different fuel combustion parameters. But till date no dedicated sensor is available in the market for this purpose. With this perspective, in the present work, we have developed a selective ethanol sensor based on La3+ impregnated TiO2, which would be capable to detect and differentiate different high concentration of ethanol in gasoline quite precisely. We have used a facile sol-gel procedure to synthesize the pristine and La-impregnated (similar to 2 to 6 at.%) titania nanopowders. The phase transformation, structural, and morphological analyses were carried out using thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray (EDX), UV-Visible and photoluminescence (PL) measurements. Taguchi type sensors were fabricated from the as-prepared powders and their ethanol sensing performances were studied. similar to 4 at.% of La concentration was found to be most efficient to stabilize the sensing favorable anatase phase of TiO2, as well as gave the best sensing response, similar to 82% in 10% ethanol at operating temperature of similar to 350 degrees C. This sensing response increased to 96% for pure ethanol. The selectivity of the sensor toward the ethanol with respect to other gases in bio-fuel was quite high. A model bio-fuel composition (E10) was also prepared and performance was evaluated
Microstructural and tribo-mechanical investigation of as-cast Ti-Zr binary alloys
No full textTitanium and its alloys are proved to be very successful in manufacturing of various types of automotive and aircraft parts. It is also used in manufacturing of some sophisticated medical instruments and medical implants purposes. Investigated titanium binary alloys in this research were Ti-5Zr and Ti-20Zr respectively. The casting process was used in an electric arc furnace to produce titanium alloys with addition of zirconium content (5% and 20%) in two different proportions separately. The primary aim of this research work was to evaluation of microstructural characterization and investigation of tribomechanical properties. XRD method was used to analyze present phases and both alloys showed martensitic hcp alpha' Ti structures complied with alpha Ti structures. FESEM was engaged to study microstructures and EDS showed that analyzed alloys have identical chemical compositions. Microhardness property was improved with the increment in Zr concentration. Resulted hardness for Ti-5Zr alloy was 305HV, while hardness was increased to 316HV for Ti-20Zr alloy. Tribological properties of binary Ti-Zr alloys were assessed with the help of a typical ball on plate set under the dry condition and at room temperature. In this case also higher Zr contain Ti binary alloy favored better tribological effects and this can be attributed from resulted COF values of Ti-Zr binary alloys. At the low load (15 N), COF values were 0.35 and 0.29 for Ti-5Zr and Ti-20Zr alloys respectively. Whereas at the high load (30 N), COF values were 0.36 and 0.34 for Ti-5Zr and Ti-20Zr alloys respectively. However, it was quite evident that adhesive wear was dominant for these Ti-Zr binary alloys. Copyright (C) 2022 Elsevier Ltd. All rights reserved
Surface-analyte interaction as a function of topological polar surface area of analytes in metal (Cd, Al, Ti, Sn) sulfide, nitride and oxide based chemiresistive materials
No full textMaterial surface - analyte interactions play important roles in numerous surface mediated processes including gas sensing. However, effects of topological polar surface area (TPSA) of target analytes on surface interactions during gas sensing have been so far largely disregarded. In this work, based on experimental observations on cross-sensitivity in cadmium sulfide (CdS) nanoparticle based room temperature gas sensor, we found that for reactions with similar Energy Rate of Surface Interaction (ERSI), unexpected quadratic correlation exists between sensing response of CdS and TPSA of analytes. From general understanding and as reported earlier in case of drug absorption through surface of membranes, it is expected that surface interactions would decrease with increasing TPSA of analytes. Our results imply that for certain TPSA range, sensor surface-analyte interactions actually increase with increasing TPSA before it finally starts decreasing. Further experiments on four other diverse material systems like AlN, SnO2, TiO2 (Anatase) and Vanadium-doped SnO2 showed similar trend, revealing generalized picture of TPSA dependence of sensor surface-analyte interactions. A physical explanation behind the parabolic relation has been provided based on electrostatic energy minimization of interacting polar fields. Above finding is anticipated to pave way to achieve improved surface interactions and highly selective sensing performances consecutively
Band gap engineered Sn-doped bismuth ferrite nanoparticles for visible light induced ultrafast methyl blue degradation
No full textRemediation of water pollution persists as major concern for scientists and industry. Various ceramic based nanomaterials have been used in efficient photocatalytic degradation of different industrial dyes. However, the major factors that restrict efficacy of these systems are requirement of UV source for activating dye degradation process, prolonged time for degradation and lower efficiency. This paves way to development of alternative material systems that can resolve above problems by not only ensuring maximum dye degradation in minimum time in presence of visible light but also reusability in several cycles. In this work, we report visible light driven photocatalytic degradation of methyl blue (MB) using Sn-doped bismuth ferrite (BFO) nanoparticles. Different concentrations (0, 1%, 1.5%, 2%) of Sn-doped BFO nanoparticles were synthesized using facile sol-gel methods. It was observed that 1.5% Sn-doped BFO nanoparticle exhibits highest photocatalytic activity towards MB degradation compared with pure and other doped BFO nanoparticles. 1.5% Sn-doped BFO nanoparticle de-lineates 70% dye degradation capability within 10 min of irradiation under visible light. 1.5% Sn-doped sample shows 99% degradation capability within 2 h of visible light irradiation while pristine BFO nanoparticles can degrade only 20% under identical conditions. Additionally, 1.5% Sn-doped BFO nanoparticles are also capable of degrading RhB, another important contaminant. The 1.5% Sn-doped BFO nanoparticle could be a promising photocatalyst for efficient degradation of industrial effluents having various dyes. The efficient dye degradation of 1.5% Sn doped BFO nanoparticle has been explained in terms of increased density of surface active sites evident from bulk structural analyses and greater probability of generation of electron-hole pairs on surface by virtue of reduced band gap. A theoretical modelling of band structure has been done to identify surface .OH ions as most effective species to promote dye degradation
Room temperature sputtered nanocrystalline SnO2 thin films sensitized with Pd nanoparticles for high performance CO gas sensing application
No full textIn the present work, we have reported that Pd sensitized nanocrystalline SnO2 thin films sputtered at room temperature are quite promising for development of CO gas sensors. The investigation of materials quality and to understand the sensing mechanism, various characterization techniques such as the GIXRD, FESEM, PL and XPS were used. The sensing characteristics of prepared samples have been measured for different concentration of CO gas and at different temperatures. An excellent sensor response (similar to 94.5%) has been achieved for Pd sensitized SnO2 at 100 degrees C temperature for CO gas of 91 ppm concentration than SnO2 thin film (sensor response similar to 13.6%). The maximum sensor responses similar to 99.5% and similar to 84.3% were observed at 200 degrees C temperature, respectively for both samples. Also, a very fast response and recovery time of about similar to 8 s and similar to 15 s was achieved for Pd sensitized SnO2 thin film. Further, it was observed that Pd sensitized SnO2 thin film was highly selective for CO gas compared to NH3, H2S, NO2 and NO gases and highly stable even after preserved for about six months. Thus, rough surface or nano-pillars/cracks on the surface can also improve the gas sensing