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The cubic Sm@CdS quantum dots (QDs) are grown in a glass matrix with good thermal stability for the first time. The band gap of CdS particles embedded in glass is observed to be in the range of 3.8 to 2.4 eV. The present system is compared with CdS/Sm nanocrystals (NCs) doped in a silica-based glass system. The CdS quantum dots, having a size in the range of 3–6 nm, are grown in the silica glass. Structural characterization has been carried out using X-ray diffraction (XRD), which shows the cubic structure of Sm@CdS quantum dots in glass, whereas the pristine CdS Q-dot glass shows hexagonal structure. The optical characterization of the glasses has been carried out using a UV-visible spectrophotometer. A spectroscopic study showed a shift in optical transmittance due to thermal treatment, i.e., due to the growth of CdS quantum dots in the glass matrix. The semiconductor crystals are uniform in size and distributed evenly in the glass matrix. The size quantization effect has been seen in both systems. There is a drastic change in the optical band gap with the size of the quantum dots. Under natural sunlight, the hydrogen production experiment was conducted, and an increase of 42.5% in the hydrogen evolution rate was observed from 1 wt% Sm3+ doped CdS (3769.2 μmol h−1 g−1) heat-treated at 525 °C when compared to the CdS Q-dot glass with a similar heat treatment temperature (2626 μmol h−1 g−1). Such cubic CdS QD–glass nanocomposites have great significance owing to their potential applications in solar cells, LEDs, and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

SnO2@C nanocomposites were synthesized using a citrate gel method in one step. Carbon has been used to increase the conductivity of pristine SnO2. The SnO2@C nanocomposites show nanoparticles sized in the range of 30–50 nm. A structural study by XRD shows the tetragonal rutile structure of SnO2. Furthermore, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy confirm the existence of SnO2 along with carbon. The electrochemical performance was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge measurements. The nanocomposite has been used as an anode material for lithium-ion batteries. Pristine SnO2 exhibited a discharge capacity of 1854 mA h g−1 and a corresponding charge capacity of 1038 mA h g−1 for the first cycle. The SnO2@C nanocomposite showed a discharge capacity of 2574 mA h g−1 and charge capacity of 1481 mA h g−1 for the first cycle. These results clearly show the effect of carbon incorporation in SnO2. Furthermore, the nanocomposite shows a discharge capacity as high as 725 mA h g−1 after 200 cycles at a current density of 50 mA g−1. Thus, the obtained capacity for the nanocomposites is much higher as compared to that for pristine SnO2, i.e., 119 mA h g−1 at 50 mA g−1 after 200 cycles. The higher capacity in the nanocomposites is due to the fast transport of electrons and easy transport of lithium ions due to the carbon in the nanocomposites. The SnO2@C nanocomposite anode exhibits superior cycling stability and rate capability due to its stable electrode structure. [ABSTRACT FROM AUTHOR]

The three-dimensional hierarchical SrS/Bi2S3 heterostructures were synthesized by a template-free single-step hydrothermal method. The structural and morphological studies revealed the formation of a single crystalline orthorhombic heterostructure with rod-like morphologies possessing a high aspect ratio. The field emission properties of SrS/Bi2S3 nanorods were investigated. J-E and the Fowler-Nordheim (F-N) plot, as well as long-term field emission (FE) stability, were studied. SrS/Bi2S3 nanoflowers have enhanced the FE properties more than the virgin Bi2S3. The observed values of the re-producible turn-on field for SrS/Bi2S3 defined to draw an emission current density of ca. 1 μA/cm² were found to be ca. 2.50 V/μm, and of the threshold field to draw a current density of ca. 10 μA/cm² were found to be ca. 3.00 V/μm (without visible light illumination). A maximum emission current density of ca. 527 μA/cm² was drawn without light and a current density of ca. 1078 μA/cm² with light, which is higher than that of pristine Bi2S3. [ABSTRACT FROM AUTHOR]

We report optical studies with magneto-optic properties of Bi2S3 quantum dot/wires-glass nanocomposite. The size of the Q-dot was observed to be in the range 3-15 nm along with 11 nm Q-wires. Optical study clearly demonstrated the size quantization effect with drastic band gap variation with size. Faraday rotation tests on the glass nanocomposites show variation in Verdet constant with Q-dot size. Bi2S3 Q-dot/wires glass nanocomposite demonstrated 190 times enhanced Verdet constant compared to the host glass. Prima facie observations exemplify the significant enhancement in Verdet constant of Q-dot glass nanocomposites and will have potential application in magneto-optical devices. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis of fragmented lignin (FL) assisted zinc oxide (ZnO) and titanium oxide (TiO2) nanocomposites. The fragmented lignin synthesized from biomass (sugarcane bagasse) was used as a template to generate the morphology and crystallite structure of metal oxide nanomaterial. The nanocomposites were synthesized by a simple precipitation method, wherein fragmented lignin is used in alkaline medium as a template. X-ray diffraction (XRD) analysis shows the phase formation of hexagonal wurtzite ZnO and mixed phase formation of TiO2 as rutile and anatase. The morphology was studied by using field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM). The FE-SEM of pristine ZnO nanocomposites showed a cluster of particles whereas FL-ZnO NPs showed self-aligned nanoparticles in the form of rod shaped having average size 30-70 nm. Pristine TiO2 nanoparticles showed clusters of particles and FL-TiO2 nanocomposites showed well crystalline 41nm size nanocomposites. The FL acts as a surfactant which restrict the cluster formations. The band gap determined by diffuse reflectance spectra is 3.10 eV and 3.20 eV for FL-ZnO and FL-TiO2 nanocomposites, respectively. Photoluminescence spectra of both nanocomposites showed structural defects in the visible region. Further, the antimicrobial activity of pristine ZnO and TiO2 nanoparticles, and FL-ZnO and FL-TiO2 nanocomposites against Escherichia coli (ATCC25922), Staphylococcus aureus (ATCC25923) were studied under UV-A (315-400 nm) (8W) for 30min. [ABSTRACT FROM AUTHOR]

Self-assembled 3D hierarchical Bi2W1−xMoxO6 heterostructures with varying x (x = 0, 0.2, 0.4, 0.6, 0.8 or 1.0) with different morphologies were synthesised via a facile one-pot solvothermal method and their photocatalytic activity towards the oxygen evolution reaction (OER) from water under natural sunlight was tested. The structural properties of Bi2W1−xMoxO6 were studied by the X-ray diffraction (XRD) technique, which showed an orthorhombic Aurivillius layered crystal structure. The microstructural features were examined by FE-SEM and FE-TEM techniques which showed that the morphology of Bi2WO6 varies with substitution of Mo and each morphological structure grows via the assembly of tiny nanoparticles of size 50 nm. The effective substitution of Mo in Bi2WO6 extends the optical absorption towards the visible region. The substitution of Mo in place of W was confirmed by X-ray photoelectron spectroscopy. The photocatalytic activities were evaluated by OER under solar light irradiation. The sample Bi2W0.6Mo0.4O6 (S3) shows enhanced photocatalytic activity for OER from aqueous AgNO3 solution (652 μmol h−1 g−1) which is higher than for pristine Bi2MoO6 or Bi2WO6 photocatalysts. Enhanced photocatalytic activity can be attributed to the extended absorption in the visible light region, which enhances the photocatalytic efficiency of the photocatalysts. More significantly, the 3D intrinsically layered nanosheet structure based morphology, and the unique band structure are beneficial for efficient charge transfer, which enhances the photocatalytic activity. This work demonstrates an effective strategy for developing an active photocatalyst with greater utilization of solar light. [ABSTRACT FROM AUTHOR]

The synthesis of orthorhombic nitrogen-doped niobium oxide (Nb2O5−xNx) nanostructures was performed and a photocatalytic study carried out in their use in the conversion of toxic H2S and water into hydrogen under UV-Visible light. Nanostructured orthorhombic Nb2O5−xNx was synthesized by a simple solid-state combustion reaction (SSCR). The nanostructural features of Nb2O5−xNx were examined by FESEM and HRTEM, which showed they had a porous chain-like structure, with chains interlocked with each other and with nanoparticles sized less than 10 nm. Diffuse reflectance spectra depicted their extended absorbance in the visible region with a band gap of 2.4 eV. The substitution of nitrogen in place of oxygen atoms as well as Nb–N bond formation were confirmed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. A computational study (DFT) of Nb2O5−xNx was also performed for investigation and conformation of the crystal and electronic structure. N-Substitution clearly showed a narrowing of the band gap due to N 2p bands cascading above the O 2p band. Considering the band gap in the visible region, Nb2O5−xNx exhibited enhanced photocatalytic activity toward hydrogen evolution (3010 μmol h−1 g−1) for water splitting and (9358 μmol h−1 g−1) for H2S splitting under visible light. The enhanced photocatalytic activity of Nb2O5−xNx was attributed to its extended absorbance in the visible region due to its electronic structure being modified upon doping, which in turn generates more electron–hole pairs, which are responsible for higher H2 generation. More significantly, the mesoporous nanostructure accelerated the supression of electron and hole recombination, which also contributed to the enhancement of its activity. [ABSTRACT FROM AUTHOR]

We have demonstrated the synthesis of Ag3PO4/LaCO3OH (APO/LCO) heterostructured photocatalysts by an in situ wet chemical method. From pre-screening evaluations of photocatalysts with APO/(x wt% LCO) composites with mass ratios of x = 5, 10, 15, 20, 25 and 30 wt%, we found that the APO/LCO (20 wt%) exhibited a superior photocatalytic activity for organic pollutant remediation. Therefore, an optimised photocatalyst APO/LCO (20 wt%) is selected for the present study and we investigate the effect of a mixed solvent system (H2O:THF) on the morphology, which has a direct effect on the photocatalytic performance. Interestingly, a profound effect on the morphological features of APO/LCO20 heterostructures was observed with variation in the ratio of the solvent system. From the FESEM study it is observed that the LCO spherical nanoparticles are transformed into nanorods with the variation of THF into the solvent system. Moreover, these LCO nanorods make intimate contact with the APO microstructures which is helpful for the improvement of the photocatalytic activity. The photocatalytic activities of the APO/LCO composites with different solvent ratios were evaluated by the degradation of rhodamine B (RhB) under visible light irradiation. Excellent photocatalytic activity was observed for the APO/LCO-2 (H2O : THF = 60 : 40) sample. This might be due to uniform covering of the APO microstructures by fine LCO rod-like structures offering intimate contact between the APO and LCO and providing proper channels for the degradation reactions. Furthermore, with an increasing THF volume ratio in the reaction system there was an increase of the dimensions of the LCO rod-like structures and also a loose compactness of their uniform intimate contact between the APO/LCO heterostructures. All in all, the enhanced photocatalytic activity of the APO/LCO heterostructures is attributed to the collective co-catalytic effect of LCO, by providing accelerated charge separation through the heterojunction interface, and THF, by helping to tune the unique morphological features which eventually facilitate the photocatalysis process. [ABSTRACT FROM AUTHOR]