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Low-cost and high-performance UV photodetector (PD) based on anatase titanium dioxide (TiO2) and nitrogen-doped graphene quantum dots (N-GQDs) bilayer heterojunction were fabricated on a commercial SiO2/Si substrate by drop-casting the N-GQDs solution on the surface of anatase TiO2 thin film, which was initially prepared by thermally oxidizing a DC-sputtered titanium (Ti) film in air. The anatase TiO2 and N-GQDs films were characterized with several techniques in order to study their structure and morphology properties. XRD, XPS, and AFM revealed that the phase of the as-sputtered Ti film transformed to a highly crystalline pure anatase TiO2 film when thermally oxidized at 600 °C in air. In addition, TEM, HRTEM, and FTIR revealed that the N-GQDs are highly crystalline and narrowly distributed in size. Furthermore, the optical and UV light harvesting properties of photodetectors based on pure anatase TiO2 film (without N-GQDs) and anatase TiO2 (with N-GQDs) were investigated. The photoresponsivity of the hybrid photodetector based on anatase TiO2/N-GQDs heterojunction has been enhanced by almost 2.5 times in magnitude than that of the photodetector based on pure anatase TiO2 film. This result was validated by elucidated energy band alignment between the anatase TiO2 and N-GQDs films, which resulted in a higher absorption rate, and an efficient transport mechanism in the hybrid junction-based photodetector than that of the pure TiO2-based photodetector.

Herein, a heterostructure of MoS2/CdS/TiO2 nanotube arrays is constructed by successive ionic layer adsorption/reaction of CdS and dipping-assembly of MoS2 on the vertically oriented TiO2 nanotubes prepared by anodization method. The heterostructure is extensively investigated in terms of the composition, morphology, structural, and optical properties. It is observed that the co-modification of TiO2 nanotube arrays with CdS and MoS2 significantly enhances the visible light response and boosts the facile photo-generated electrons’ transfer and charge separation efficiencies. Therefore, the prepared heterostructure photo-anode exhibits significantly enhanced photoelectrochemical properties including photocurrent, open circuit potential, and photo-conversion efficiencies compared with that of pure TiO2 nanotube arrays and CdS/TiO2 nanotube systems. Interestingly, it is found that the MoS2 coatings on the surface of CdS/TiO2 nanotube arrays greatly enhance their photoelectrochemical stability. The presented work demonstrates that MoS2/CdS/TiO2 nanotube heterostructures are a promising material for improved photoelectrochemical properties. A heterostructure of MoS2/CdS/TiO2 nanotube arrays was constructed by successive ionic layer adsorption/reaction of CdS and dipping-assembly of MoS2 on the vertically oriented TiO2 nanotube arrays, and their improved photoelectrochemical properties were demonstrated

In this paper, pure SnO2 and Ce-doped SnO2 nanosheets were synthesized through a facile hydrothermal method. The synthesized materials were characterized by different techniques for their physico-chemical properties. The XRD data indicated the characteristic tetragonal rutile crystal phase for SnO2. Ce doping was ascertained by the presence of the diffraction peaks of CeO2 in all the doped samples of the SnO2 nanosheets. FESEM images revealed highly rough surfaces as well as the agglomeration of a large number of small nanoparticles of multiple shapes to form nanosheets like morphologies for pure SnO2 and Ce-doped SnO2. Electrochemical techniques like cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry were applied to demonstrate the electrochemical performances of the pure SnO2 and Ce-doped SnO2 nanosheets/Nafion-modified glassy carbon electrode (GCE). The 3% Ce-doped SnO2 nanosheet/Nafion-modified GCE showed a remarkable sensitivity of 0.9986 μA μM−1 cm−2 over a linear dynamic range of 0.5–20.3 µM. The corresponding linear regression equation was Ip (μA) = 0.0709 [2-nitroaniline (μM)] + 0.1385 with R2 = 0.99325. The LOD of the modified sensor was found to be 6.3 ± 0.1 nM at the signal-to-noise ratio of S/N = 3. The newly developed sensor electrode exhibited good selectivity toward 2-nitroaniline in the presence of common interfering species. Fabrication and characterization of highly sensitive and selective 2-nitroaniline chemical sensor based on cerium-doped tin oxide nanosheets/Nafion-modified glassy carbon electrode.

Ethanol is one of the volatile organic compounds as well as organic pollutants that is essentially to be monitored using high response sensors. Semiconducting metal oxide nanostructures can be the potential sensor material for high-performance ethanol sensing application. Herein, we present the fabrication and characterization of highly sensitive and selective ethanol gas sensor based on flower-shaped CuO composed of thin nanoplates synthesized by facile hydrothermal process. The prepared flower-shaped CuO was examined by various techniques viz FESEM, XRD, EDS, elemental mapping, HRTEM, SAED, UV-visible spectroscopy, FTIR spectroscopy, and Raman spectroscopy, which confirmed the high-density growth, monoclinic crystal structure, and optical band gap of ~2.5 eV. The fabricated resistive sensor device based on flower-shaped CuO, at optimum experimental conditions, i.e., 250 °C, 100 ppm ethanol concentration, exhibited a high sensing response of 241%, while, at 10 ppm of ethanol concentration, the response was observed to be 5%. The transient responses as well as the stability of the sensor were analyzed and reported here. The selectivity of CuO sensor device was studied for NO2, CO2, CO, and CH4 gases and remarkably it was seen that the developed gas sensor devices demonstrated outstanding selectivity toward ethanol gas. Finally, the gas response mechanism of the fabricated resistive ethanol gas sensor was explained on the basis of the ionosorption model.

Methylene blue intercalated layered MnO2 nanosheets (MB-MnO2) were synthesized through an ex-situ method at room temperature. Tetramethylammonium hydroxide (TMAOH) was used as a delaminating agent for the synthesis of nanosheet-like structures of MnO2. The prepared nanocomposites were analyzed by various instrumental techniques such as UV–visible, FTIR, XRD, FESEM, and EDX for the close examination of the morphology, structure, shape, crystallinity, and vibrational characterization. Typical two-dimensional layer sheet-like morphologies with multiple folds were observed for non-intercalated MnO2, whereas intercalated MnO2 showed more flattered and planar square-shaped and elongated ultrathin sheet-like structures with occasional folds and crinkles. MB intercalated MnO2nanosheets were used as an efficient electron mediator for the electrooxidation of the ascorbic acid to dehydroascorbic acid. Cyclic voltammetry and chronoamperometry confirmed the excellent electrocatalytic activity of the modified MB intercalated MnO2 nanosheets/GCE over a wide range of ascorbic acid concentrations in 0.1 M PBS. The detection limit was computed to be 0.05 μM. The effect of the scan rates and concentration of the ascorbic acid were also analyzed.

Herein, we report the facile solution phase precipitation synthesis of ZnO nanoparticles doped with various concentrations, i.e. 1, 5 and 10 mol% of lanthanum (La). The synthesized nanoparticles were characterized in detail by several techniques which confirmed the high-density growth and well-crystalline nature of La-doped ZnO nanoparticles. The XRD results revealed the successful incorporation of 1 mol% La ions in the hexagonal wurtzite structure of ZnO; however, small XRD peaks of La2O3 were detected in 5 and 10 mol% La-doped samples. All the La-doped nanoparticles were found to be UV responsive. For the application prospective, all the synthesized nanoparticles were used as photocatalyst for the photocatalytic degradation of three toxic dyes, i.e. methyl orange (MO), Rhodamine B (Rh B) dyes and picric acid (PA). By detailed photocatalytic investigations, interestingly, 1 mol% La-doped ZnO was found to be most efficient photocatalyst towards the degradation of all three organic dyes. Further, the synthesized nanoparticles were also used as fluorescent probe for the fluorescence sensing of picric acid (PA). Remarkably, the 1 mol% nanoparticles exhibited highest sensitivity, i.e. lowest limit of detection (LOD) value (1.05 µM L−1) towards PA compared to 5 and 10 mol% (1.38 µM L−1) La-doped ZnO nanoparticles.

Herein, we report, for the first time, the facile synthesis of VO2(paramontroseite) by doping of Ge4+ ions into VO2 via simple hydrothermal route. The synthesized materials were characterized by different techniques in terms of their structural, morphological, and thermal properties using X-ray diffraction, transmission electron microscopy, and thermogravimetric analysis and differential scanning calorimetry, respectively. It was observed that the formation of a tunnel by the octahedral arrangement of VO6 in VO2(P) allows intercalations of ions from ionic electrolytes, making it useful for electrochemical applications. The detailed cyclic voltammetric studies, at different scan rates, and electrochemical impedance spectroscopic results showed that the VO2(P) is a potential material for electrochemical applications.

Herein, we report the enhanced solar light-mediated photocatalytic degradation of brilliant green dye using BiPO4 nanospindles and MoS2/BiPO4 nanorods synthesized by facile hydrothermal process. The synthesized nanomaterials were examined by various techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM) attached with energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller, and pore size distribution analysis. The detailed characterizations revealed that after the introduction of MoS2, the crystalline phase transformation from hexagonal to monoclinic was observed for BiPO4. The TEM images clearly confirmed that BiPO4 possessed nanospindles and MoS2/BiPO4 exhibited nanorod-shaped morphologies. The photocatalytic activity of synthesized MoS2/BiPO4 nanorod heterojunction was explored for the degradation of brilliant green (BG) dye under solar light irradiation. Interestingly, approximate 80% degradation of BG was observed under solar light in 70 min using MoS2/BiPO4 nanorods as photocatalyst. As an efficient photocatalyst, the synthesized MoS2/BiPO4 nanorod heterojunction exhibited enhanced photocatalytic efficiency as compared to pure BiPO4 nanospindles, commercially available TiO2PC-50 and TiO2 PC-500 under solar light. The high photocatalytic activity of MoS2/BiPO4 nanorod heterojunction could be related to the amended visible light-harvesting tendency, effective charge separation, and facile transportation of photogenerated e−/h+ pairs at the heterojunction interface.

Copper selenide and copper telluride nanostructures were synthesized using Bovine serum albumin, for the first time, via a facile hydrothermal method. The involvement of different precursors was proposed through a probable reaction mechanism. Moreover, the structural and optical properties of the prepared Cu(2−x)Se and Cu(2−x)Te nanostructures were investigated. The average sizes of the synthesized copper selenide nanoparticles were in the range of 87 ± 24 nm. Variation in size and shape for copper telluride nanostructures gave round shape nanoparticles as well as rods in micro and nano size and average size for small and large round shape nanoparticles were 52 ± 16 nm and 216 ± 27 nm, respectively. More precisely, size-strain plot and the Williamson-Hall analysis methods were adopted to determine the lattice strain and crystalline sizes of the synthesized nanoparticles. The optical band gap energy of prepared nanoparticles estimated from the UV–Vis spectroscopy was 2.95 and 2.32 eV for Cu(2−x)Se and Cu(2−x)Te nanoparticles, indicating quantum confinement effect due to the deviation from bulk materials to the nanoscale. Moreover, the band gap decreased with enhancement of BSA concentration which suggest that the usage of BSA content is important factor and must be optimized for obtaining desired optical band gap. The electrical conductivity for copper selenide and copper telluride was found as 0.048 − 0.064 × 105 S cm−1 and 0.011 − 0.017 × 106 S cm−1 respectively.

Recently, the environmental pollutions (air, water and soil) caused by the release of large amount of toxins, through extensive industrialization, have received a great attention by the environmental scientists. Thus, there is a serious need for efficient environmental remediation approaches. Recently, nanomaterials have obtained immense interest due to their enormous prospective in the environmental remediation. Researchers have developed biocompatible and safer tools for the development of nanomaterials. This review article is demonstrating that how different biocompatible nanomaterials are synthesized and used for the ecological remediation applications. Different schemes are explained for the synthesis of nanomaterials with high biocompatibility and their application in the field of environmental remediation. The use of various functional nanomaterials for the treatment of environmental pollutions (air, water and soil) is discussed in detail.

Carbon nanomaterials (CNMs), especially carbon nanotubes (CNTs) with coiled structure exhibit scientifically fascinating. They may be projected as an innovative preference to future technological materials. Coiled carbon nanotubes (c-CNTs) on a large-scale were successfully synthesized with the help of bi-metal substituted α-alumina nanoparticles catalyst via chemical vapor deposition (CVD) technique. Highly spring-like carbon nanostructures were observed by field emission scanning electron microscope (FESEM) examination. Furthermore, the obtained material has high purity, which correlates the X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) analysis. Raman spectroscopy reveals that the carbon multi layers are well graphitized and crystalline, even if they have defects in its structure due to coiled morphology. High-resolution transmission electron microscope (HRTEM) describes internal structure and dia of the product. Ultimately, results support the activity of bi-metal impregnated α-alumina nanoparticles catalyst to determine the high yield, graphitization and internal structure of the material. We have also studied the purified c-CNTs magnetic properties at room temperature and will be an added advantage in several applications.

Silicon (Si) nanowires offer great potential for field ionization (FI) applications due to well-established Si microfabrication methods combined with favorable ionizing properties of Si. Band bending of semiconductors under applied electric fields increases the FI probability, which is not possible with metal-based counterparts. While it has been demonstrated that scaling down the active material geometry can increase the FI efficiency, maximum electric field at the tip of a single nanowire decreases by quenching effect of nearby nanowires. In this work, optimization of Si nanowire geometries for improved FI efficiencies is explored.

ZnO and hematite (Fe2O3) nanoparticles (NPs) have been used as electrocatalysts or electron mediators for the modification of gold (Au) electrode for the detection of toxic compounds, i.e., para-nitrophenol (PNP). A comparison of the two types of NPs reveals higher efficiency for ZnO NPs. Electrochemical response measured by three different techniques, i.e., normal cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometry, has been used to determine the sensitivity and detection limit of the system. The order of sensitivity varies in the order: amperometry > DPV > normal CV response, both for ZnO and α-Fe2O3 NPs. While, the order of detection limit for α-Fe2O3 NPs varies as DPV > normal CV > amperometry and for ZnO NPs, the order is normal CV > DPV > amperometry, suggesting that amperometry is the best among all the techniques for detection applications. Based on the electrochemical response, it is proposed that the electrochemical reaction of PNP proceeds via two-step mechanism. In the first step, irreversible reduction of PNP to para-hydroxy nitrophenol takes place with the gain of four electrons and in the second step, reversible redox reaction occurs by the exchange of two electrons, from hydroxy nitrophenol to nitrosophenol and vice versa.

Pt/K2CO3/MgAlOx–reduced graphene oxide (Pt/K/MgAlOx–rGO) hybrids were synthesized, characterized and tested as a promising NOx storage and reduction (NSR) catalyst. Mg–Al layered double hydroxides (LDHs) were grown on rGO via in situ hydrothermal crystallization. The structure and morphology of samples were thoroughly characterized using various techniques. Isothermal NOx adsorption tests indicated that MgAlOx–rGO hybrid exhibited better NOx trapping performance than MgAlOx, from 0.44 to 0.61 mmol · g−1, which can be attributed to the enhanced particle dispersion and stabilization. In addition, a series of MgAlOx–rGO loaded with 2 wt% Pt and different loadings (5, 10, 15, and 20 wt%) of K2CO3 (denoted as Pt/K/MgAlOx–rGO) were obtained by sequential impregnation. The influence of 5% H2O on the NOx storage capacity of MgAlOx–rGO loaded with 2 wt% Pt and 10% K2CO3 (2Pt/10 K/MgAlOx–rGO) catalyst was also evaluated. In all, the 2Pt/10 K/MgAlOx–rGO catalyst not only exhibited high thermal stability and NOx storage capacity of 1.12 mmol · g−1, but also possessed excellent H2O resistance and lean–rich cycling performance, with an overall 78.4% of NOx removal. This work provided a new scheme for the preparation of highly dispersed MgAlOx–rGO hybrid based NSR catalysts.

Apparent molar volumes (ϕv), apparent molar adiabatic compressions (ϕκ) and thermodynamic parameters of cetyltrimethyl ammonium bromide (CTAB) in 0.001, 0.01, 0.05 and 0.1 mol·dm−3 aqueous solution of glycine in the temperature range 25–40 °C (at an interval of 5 °C) have been determined from density, speed of sound and conductometric measurements, respectively. The above calculated parameters were found to be sensitive to the interactions prevailing in the glycine–CTAB–water system. The analysis of the data was found to suggest that the ϕv and ϕκ values decrease sharply in the pre-micellar region and thereafter the decrease is almost linear at all concentrations of glycine, showing the dominance of hydrophobic interactions and facilitating the process of micellization. The ϕv and ϕκ values of these surfactants are found to be completely consistent with temperature over the entire concentration range. From conductance studies, the value of critical micelle concentration has been calculated, which shows dependence on the concentration of glycine as well as on temperature. A reasonably good qualitative correlation is found to exist with regard to CTAB–glycine interactions obtained from the conductance measurements and those from density and sound velocity measurements. All these observations demonstrate that this amino acid–surfactant system behaves in a different manner as compared to amino acid–electrolyte systems.

We present a fully microscopic study of the $^{16}$O+$^{208}$Pb fusion using the density-constrained time-dependent Hartree-Fock theory. The calculated fusion cross-sections are in good agreement with the experimental data for the entire energy range indicating that the incorporation of dynamical effects is crucial in describing heavy-ion fusion., 5 pages, 3 figures

We analyze the details of mass exchange in the vicinity of the Coulomb barrier for heavy-ion collisions involving neutron-rich nuclei using the time-dependent Hartree-Fock (TDHF) theory. We discuss the time-dependence of transfer and show that the potential barriers seen by individual single-particle states can be considerably different than the effective barrier for the two interacting nuclei having a single center-of-mass. For this reason we observe a substantial transfer probability even at energies below the effective barrier., Comment: 6 pages, 9 figures

Well-crystallized ZnO nanoneedles were grown on Au-coated Si(100) substrate by cyclic feeding chemical vapor deposition (CFCVD) process using diethyl zinc and oxygen as precursors for zinc and oxygen, respectively. Morphological investigations revealed that the as-grown nanoneedles exhibited sharpened tips and wider bases, having the typical diameters at their bases and tips, 60±10 nm and 20±10 nm, respectively. Detailed structural characterizations confirmed that the as-grown products were single crystalline with a wurtzite hexagonal phase and were grown preferentially along the [0001] direction. The room-temperature photoluminescence (PL) spectrum showed a strong and sharp UV emission at 378 nm with a very weak, suppressed and broad green emission at 520 nm, substantiating good optical properties for the as-grown ZnO nanoneedles.

ZnO nanowires having a diameter in the range of 15–40 nm and several tens of micrometers in length were grown on steel alloy substrates by the thermal evaporation technique without the use of any catalyst or additives. A detailed structural analysis revealed that the as-grown ZnO nanowires are single crystalline with wurtzite hexagonal structures and preferentially oriented in the c-axis direction. Origination of a strong and sharp Raman-active E2 mode at 436.6 cm-1 indicated that the grown ZnO nanowires have good crystal quality with the hexagonal wurtzite phase. Photoluminescence spectra also exhibited a sharp and strong peak in UV and a suppressed and weak band in the visible region, confirming the good optical properties and less structural defects for the deposited products. Additionally, a systematic growth mechanism is also proposed in detail to acquire a better understanding for the growth of nanowires on steel alloy substrate.

Synthesis of ZnO nanowires was achieved on Si(100) substrate by the thermal evaporation of high purity metallic zinc powder without the use of any metal catalyst or additives. The diameter and length of the as-grown nanowires were in the range of 20–35 nm and few micrometers, respectively. The shapes and sizes of ZnO nanowires were dependent on the growth time. The high resolution transmission electron microscopy and selected area electron diffraction patterns indicated that the as-grown products are single crystalline with wurtzite hexagonal phase. Room temperature photoluminescence studies exhibited a strong UV emission and a suppressed green emission, confirming the good optical properties for the deposited nanowires.

ZnO nanostructures with different morphologies and sizes were synthesized on silicon substrate simply by the thermal evaporation of high-purity metallic zinc powder in the presence of oxygen without the use of any catalyst or additives. It was observed that the substrate temperature and the distance of the substrate from the source material play a critical role to determine the morphologies and sizes of the deposited structures. Scanning electron microscopic observations revealed that different types of nano- and microstructures, such as ZnO pyramid-shaped nanotowers, nanowires attached with the sheet-like structures, nanorods, microcages, and microtubes were obtained at different temperature zones with specific distances of the substrate from the source material. High-resolution transmission electron microscopy and x-ray diffraction studies confirm that the deposited products are single crystalline with wurtzite hexagonal structures. The room-temperature photoluminescence spectra of all the deposited structures displayed a strong near-band-edge emission with negligible green emission.

We present the first set of results of solving the Hartree-Fock-Bogoliubov equations, which describe the self-consistent mean field theory with pairing interaction. Calculations for even-even nuclei are carried out on a two-dimensional axially symmetric lattice, in coordinate space. An important aspect of our method is the proper representation of the quasi-particle continuum wavefunctions, which are considered for energies up to 60 MeV. This stage is essential for a proper description of nuclei near the drip Unes, due to the strong coupling between weakly bound states and the particle continuum for such nuclei. High accuracy is achieved by representing the operators and wavefunctions using the technique of basis-splines. Calculations for Sn isotopes are presented to demonstrate the reliability of the method.

Using the Hartree-Fock-Bogoliubov (HFB) mean-field theory in coordinate space, we investigate ground-state properties of the zirconium isotopes from the line of stability up to the two-neutron dripline ( 102-122Zr). In particular, we calculate two-neutron separation energies, quadrupole moments, and r.m.s. radii for protons and neutrons. We find large prolate ground-state deformations for the isotopes 102Zr through 112Zr, and the spherical shapes starting from 114Zr up to the dripline nucleus 122Zr.

We present preliminary results for TDHF studies of low-energy nuclear collisions involving deformed nuclei. The computations are performed using our highly accurate 3D TDHF code, with no assumed symmetries. The code uses Basis-Splines for discretization and is written in Fortran 95.

Sea urchin-like nanostructures of ZnO consisting of ZnO nanowires with blunt faceted ends were grown on Si (100) substrates by oxidation of metallic Zn at 600 °C. ZnO nanowires having a diameter of 30–60 nm and length of 2–4 Μm were in similar shape with uniform diameter along its entire length with well faceted blunt ends. X-ray diffraction and transmission electron microscope analysis showed that the as-grown nanostructures were highly crystalline with wurtzite hexagonal structure having lattice constants of a=b=3.25 a and c=5.21 a. Room temperature photoluminescence (PL) measurements showed a weak near band-edge emission at 380 nm, but a strong green emission at 500–530 nm. A model for vapor-solid (VS) growth mechanism of ZnO nanowires was presented, in which nucleation of ZnO is crucial for the growth of the nanostructures.