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In our current endeavor, 3-dimensional (3D) tungsten oxide (WO3) nanostructures (nanocubes, nanobars and nanobricks) have been swiftly generated via hydrothermal route at 160 °C for 24 h. Physico-chemical characterization of the resultant powder revealed formation of WO3 nanostructures with predominantly faceted cube, brick and rectangular bar-like morphology. The present study was also aimed at exploring the antimicrobial and anticancer potential of WO3 nanostructures. Antimicrobial activity was tested against different micro-organisms viz., Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli and Aspergillus fumigatus. The antibacterial and antifungal activity was ascertained against these micro-organisms by measuring the diameter of inhibition zone in agar well diffusion test which revealed that the resultant WO3 nanostructures acted as excellent antibacterial agents against both bacteria and fungi but were more effective against the fungus, A. fumigatus. To examine the growth curves of bacterial cells, time kill assay was monitored for E. coli, against which significant antibacterial action of WO3 nanostructures was noted. The anti-cancer activity of WO3 nanostructures was found to be concentration-dependent against KB cell line by viable cell count method. In our pilot study, WO3 nanostructures suspension with concentration in the range of 10−1 to 10−5 mg/ml was found to kill KB cells effectively.

Development of highly sensitive, stable and reliable eco-friendly gas sensors is still an open-ended research domain and thus demands many related materials. Bismuth-based compounds form an important material platform in such developments; however, they are so far not reviewed. This review highlights the detailed gas sensing attributes for a range of gases and humidity for n-type and p-type as well as mixed composite materials and influences of catalytic doping on gas sensing in different bismuth-based composites. The future scope in the development of such gas sensors leading to commercialization is also discussed.

In present study, hollow urchin-like nanostructures of Nb2O5 with elongated nanofilaments as photoanode material for dye-sensitized solar cells (DSSCs) are successfully synthesized at different reaction times (viz. 12, 24, and 40 h, respectively, named as samples NB-1, NB-2, and NB-3) using facile hydrothermal route. We have studied the significant influence of hydrothermal reaction time on the structural, optical, morphological, and electrical properties. The photovoltaic performance of different samples is understood from response of current-potential (J-V) curve and incident photon-to-current efficiency (IPCE) while charge recombination behavior and resistance of the cells are studied by electrochemical impedance spectroscopy (EIS). The X-ray diffraction (XRD) study shows the orthorhombic crystalline form for the synthesized samples. Electron microscopy studies confirm the formation of porous spherical morphology with hairy filaments protruding outward. Size of urchin-like particle is found to be in the range of about 1 μm diameter, and the filaments emerging out from the surface of hollow spheres are seen to be 30–70 nm long and 5–20 nm in diameter. The DSSCs fabricated from the resultant nanostructures show the better photovoltaic performance with Nb2O5 sample synthesized at 24-h reaction time. The Jsc and efficiency for NB-2 are 8.24 mAcm−2 and 3.58% respectively, which are better than corresponding samples synthesized at the reaction time of 12 h and 40 h, respectively. These photovoltaic results obtained from the DSSCs fabricated using Nb2O5 nanostructures are comparatively exciting with TiO2 spheres. By further optimizing reaction conditions, it is expected that niobium pentoxide can emerge as better semiconductor oxide for photovoltaic and optical devices.

Economical fabrication of semiconductor nanomaterials based gas sensor operating at relatively low temperature is very essential. Herein, nanostructured NixSn1-xO2 (where x = 0, 0.01, 0.05 and 0.1) powders were synthesized using facile solvothermal method at 200 °C for 24h. These powders were characterized using various analytical techniques viz. X-ray diffractometry, scanning electron microscopy, field emission transmission electron microscopy to understand their physico-chemical properties. Thick film pastes were formulated for the synthesized nanopowders. The thick films were printed on to glass substrates and fired at 400 C for 1h. The gas sensing performance of the resultant thick films was studied for hydrogen and ammonia. Thick film gas sensor based on Ni0.01Sn0.99O2 nano powder exhibited highest responseto hydrogen gas at lowest operating temperature (78 °C). On the other hand, the highest response to ammonia gas at lowest operating temperature (74 °C) was obtained in case of thick film gas sensor fabricated using nano powder of Ni0.1Sn0.90O2

Electricity generation using simple and cheap dye-sensitized solar cells and photocatalytic water splitting to produce future fuel, hydrogen, directly under natural sunlight fascinated the researchers worldwide. Herein, synthesis of indium-doped wurtzite ZnO nanostructures with varying molar percentage of indium from 0.25 to 3.0% with concomitant characterization indicating wurtzite structure is reported. The shift of (002) reflection plane to higher 2θ degree with increase in indium-doping thus is a clear evidence of doping of indium in zinc oxide nanoparticles. Surface morphological as well as microstructural studies of In@ZnO exhibited generation of ZnO nanoparticles and nanoplates of diameter 10–30 nm. The structures have been correlated well using computational density functional (DFT) studies. Diffuse reflectance spectroscopy depicted the extended absorbance of these materials in the visible region. Hence, the photocatalytic activity towards hydrogen generation from water under natural sunlight as well as efficient DSSC fabrication of these newly synthesized materials has been demonstrated. In-doped ZnO exhibited enhanced photocatalytic activity towards hydrogen evolution (2465 μmol/h/g) via water splitting under natural sunlight. DSSC fabricated using 2% In-doped ZnO exhibited an efficiency of 3.46% which is higher than other reported In-doped ZnO based DSSCs.

We report tunable-morphology oriented facile yet scalable route to synthesize 1D (nanorod) and 2D (nanobelt) MoO3 nanostructures at gram scale using conventional as well as sonochemistry assisted sol–gel technique. The structural, morphological and optical properties of the samples can be befittingly altered by varying the synthesis protocol. The resultant orthorhombic MoO3 nanomorphs demonstrated efficient and expeditious photocatalytic degradation of the pollutant dye, Methylene Blue (MB). We have observed that appreciable photocatalytic MB dye-degradation can be accomplished within 30 minutes with high rate constants of 0.0786 min−1 and 0.233 min−1 for rod and belt-like MoO3-nanostructures, respectively. The pilot results indicate that the resultant MoO3 nanomorphs can be potentially used as solar light driven industrial photocatalyst material with their intrinsic photostability.

Herein, we report facile hydrothermal synthesis of hierarchical MoS2 -based nanomorphs (displaying onion-flower-like features) with the primary focus on field-emitter applications. The synthesized nanostructures were characterized physicochemically to understand their basic structural and morphological features. Interesting nanoscale morphological evolution of onion-flower-like MoS2—from plain nanoflowers to those containing seedpods—is observed with the change in hydrothermal reaction time from 9 h to 21 h. Peculiarly, MoS2 nanomorphs with only onion-flower-like morphology displayed lower turn-on field value of 3.7 V/μm as compared to 4.2 V/μm for the nanoflowers containing seedpod-like particles. This might be attributed to the possibility of an easy electron conduction path available for the petals in plain nanoflowers, which may be impeded by the seedpod-like particles in the latter case.

One-pot green synthesis of propargylamines using ZnCl2 loaded TiO2 nanomaterial under solvent-free conditions has been effectively accomplished. The aromatic aldehydes, amines, and phenylacetylene were reacted at 100 °C in the presence of the resultant catalyst to form propargylamines. The nanocrystalline TiO2 was initially synthesized by a sol–gel method from titanium(IV) isopropoxide (TTIP) and further subjected to ZnCl2 loading by a wet impregnation method. X-ray diffraction (XRD) patterns revealed the formation of crystalline anatase phase TiO2. Field emission scanning electron microscopy (FESEM) showed the formation of agglomerated spheroid shaped particles having a size in the range of 25–45 nm. Transmission electron microscopy (TEM) validates cubical faceted and nanospheroid-like morphological features with clear faceted edges for the pure TiO2 sample. Surface loading of ZnCl2 on spheroid TiO2 nanoparticles is evident in the case of the ZnCl2 loaded TiO2 sample. X-ray photoelectron spectroscopy (XPS) confirmed the presence of Ti4+ and Zn2+ species in the ZnCl2 loaded TiO2 catalyst. Energy-dispersive X-ray (EDS) spectroscopy also confirmed the existence of Ti, O, Zn and Cl elements in the nanostructured catalyst. 15% ZnCl2 loaded TiO2 afforded the highest 97% yield for 3-(1-morpholino-3-phenylprop-2-ynyl)phenol, 2-(1-morpholino-3-phenylprop-2-ynyl)phenol and 4-(1,3-diphenylprop-2-ynyl)morpholine under solvent-free and aerobic conditions. The proposed nanostructure-based heterogeneous catalytic reaction protocol is sustainable, environment-friendly and offers economic viability in terms of recyclability of the catalyst.

In dye-sensitized solar cells (DSSCs), the semiconductor photo-anode film plays a significant role in enhancing the overall power conversion efficiency. ZnO is considered as the futuristic hope for photoanodes in DSSCs due to manifold properties over TiO2. However, the power conversion efficiency of ZnO-based DSSCs is still low due to its poor chemical stability and surface defects. In this work, we reported the synthesis of ZnO nano-flowers as well as its surface modification of with TiCl4 at different concentration. In DSSCs, the enhancement in power conversion efficiency results suggested that surface modification of ZnO film by TiCl4 leads to the deposition of TiO2 which subsequently increases the roughness factor of film as well as scattering layer. This preferential surface modification of ZnO film facilitates the accumulation of large number of photo-injected electrons in the HOMO of the photoanode with rapid transfer of charge carriers to FTO via ZnO layer by lowering the recombination of photo-injected electrons with the redox electrolyte as well as oxidized dye. The intensity-modulated photocurrent spectroscopy (IMVS) and intensity-modulated photovoltage spectroscopy (IMPS) study also indicated that the recombination rate decreased considerably during the electron transportation. The ZnO film surface modified by TiCl4 achieved a power conversion efficiency of 4.48%, which is two times higher than that of the non-modified ZnO photoanode.

In this work, we reported the synthesis of zinc sulphide microspheres using the hydrothermal method. ZnS microspheres were synthesized using water, zinc acetate, thiourea and ammonia solution at 150°C for 6 h, 12 h, and 24 h. The as-synthesized ZnS powders were characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet–visible (UV–Vis) spectroscopy. XRD indicates the cubic (major phase) as well as hexagonal (minor phase) crystalline phase with enhanced crystallinity increased gradually with more reaction time. UV–Vis spectra show the absorption peaks in the UV–Vis region for all the samples. The Tauc’s plot was used to calculate the band gap energy of ZnS samples, which are found to be 3.39 eV, 3.4 eV, and 3.42 eV for the samples synthesized at reaction times of 6 h, 12 h, and 24 h, respectively. FESEM images confirm the formation of microspheres as aggregates of spherical nanoparticles. The as-synthesized ZnS microspheres have been explored for solar light-induced photo-catalytic dye degradation of methylene blue (MB), and the results confirm that such microspheres exhibit effectual photocatalytic properties. Zinc sulphide microspheres have been synthesized hydrothermally at different reaction times (6 h, 12 h, and 24 h). The as-synthesized ZnS microspheres were successfully employed as photocatalyst for MB dye degradation. Due to high crystallinity, ZnS microspheres synthesized for 24 h show more efficient degradation potential than others.

Thin films of covellite copper sulphide (CuS) were deposited on FTO substrates using chemical spray pyrolysis technique. Influence of Cu-to-S molar ratio on structural, surface morphological, optical and electrical properties were systematically investigated using variety of characterization techniques. Formation of covellite CuS films was confirmed by low angle-XRD and Raman spectroscopy. The field emission scanning electron microscopy analysis revealed the formation of faceted CuS particles without secondary growth. Optical studies exhibited decrease in optical band gap (from 2.21 to 1.69 eV) with increase in Cu-to-S molar ratio. Electrical properties were investigated using Van der Pauw four point probe method and Hall measurements revealed that as-synthesized CuS films have low sheet resistance (1.47–2.45 Ω/□), high carrier mobility (8.90–54.89 cm2/Vs) and high sheet concentration (1016–1018/cm2). The CuS films deposited at optimized Cu-to-S molar ratio (1:2.5) were then further studied for electrochemical impedance spectroscopy and photovoltaic characteristics. A quantum-dot sensitized solar cell incorporating optimized CuS film as counter electrode showed power conversion efficiency of ~ 1.05% with Voc ~ 0.46 V, Isc ~ 1.01 mA/cm2 and fill factor ~ 0.34%. Although the cell is not fully optimized and better results can be anticipated.

Hierarchically nano-structured ZnO microspheres have been synthesized solvothermally at variable reaction times (6, 12, 36, and 48 h) by using ethylene glycol as a solvent, zinc acetate as precursor, and hexamethylene triamine (HMT) as structure directing agent. The study also focused on the mechanism of time-dependant growth of hierarchical ZnO microspheres and their deployment in dye-sensitized solar cells (DSSCs) as photoanode. Longer reaction times lead to formation of nearly spherical ZnO microspheres. The structural and morphological analysis reveals the formation of a wurtzite hexagonal crystalline structure having a microsphere-like morphology. ZnO hierarchical microspheres synthesized at different reaction times have been used as photoanode in DSSCs which show enhanced light-harvesting properties than the commercial ZnO powders. ZnO microspheres synthesized at 48 h show maximum current density and cell efficiency of 8.51 mA/cm2 and 3.31%, respectively. This enhancement in photovoltaic parameters could be due to highly porous microspheres which provide more specific surface area for dye loading, retardation of recombination, and better charge transport.

In present work, thin films of CZTS have been prepared by chemical spray pyrolysis (CSP) by spraying precursor solution directly onto the soda lime glass (SLG) substrates by varying sulphur molar concentration. Copper chloride [CuCl2.2H2O], zinc chloride [ZnCl2.2H2O], tin chloride [SnCl4.5H2O] and thiourea [(NH2)2CS] were used as precursor materials to deposit CZTS thin films by using home-built chemical spray pyrolysis system. Influence of sulphur variation on structural, optical, morphology and electrical properties of CZTS films have been investigated by using variety techniques such as low angle x-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), UV-Visible spectroscopy, four probe method, etc. The formation of CZTS has been confirmed by low angle XRD and Raman spectroscopy. The structural analysis reveals formation of kesterite tetragonal phase with preferential orientation along (112) direction. The band gap values of CZTS thin films have been calculated and found in the range 2 - 2.25 eV over the entire range of sulphur variation studied. The change in band gap may be due to quantum confinement effects at nanoscale. The morphological studies show formation of islands of nanoscale particulate clusters which constitute the films in most of the samples. The films exhibit higher resistivity values (in KΩ) which may be due to presence of the strain in the films.

Innovative colorimetric biosensing platform has been realized by in-situ synthesis of silver nanoparticles in silk-fibroin matrix derived from domesticated silkworm species Bombyx mori. As-synthesized nano-biocomposite dispersion was characterized by UV-Vis spectroscopy and transmission electron microscopy. In a pilot attempt to develop hassle free on-site screening protocol, such green hybrid systems were explored for colorimetric detection of broad range of metal ion targets, viz. toxic heavy metals such as mercury and chromium (which adversely affect hydrosphere, lithosphere, anthroposphere and biosphere) as well as relatively less-toxic metals like copper and iron in a solution. Quite interestingly, our simple biointerfacial-sensing approach reveals highly selective colorimetric sensor response down to ppb level for mercury ions analyte.

The SnO/SnO2 nanocomposites were synthesized using semisolvothermal reaction technique. These nanocomposites were prepared using different combination of solvents viz., ethanol, water, and ethylene glycol at 180 °C for 24 h. The synthesized nanocomposites were analyzed with various characterization techniques. Structural analysis indicates the formation of tetragonal phase of SnO2 for the sample prepared in ethanol, whereas for other solvent combinations, the mixture of SnO and SnO2 having tetragonal crystal structures were observed. The optical study shows enhanced absorbance in the visible region for all the prepared SnO/SnO2 nanocomposites. The observed band gap was found to be in the range of 3.0 to 3.25 eV. Microstructural determinations confirm the formation of nanostructures having spherical as well as rod-like morphology. The size of nanoparticles in ethanol-mediated solvent was found to be in the range of 5 to 7 nm. Thermogravimetric analysis indicate the weight gain around 1.3 wt% confirming the conversion of SnO to SnO2 material. The photocatalytic activity of synthesized nanocomposites was evaluated by following the aqueous methylene blue (MB) degradation. The sample prepared in ethylene glycol-mediated solvent showed highest photoactivity having apparent rate constant (Kapp) 0.62 × 10−2 min−1.

The hierarchically structured ZnO pomegranates as well as hollow spheres have been prepared in a solvothermal assisted process using ethylene glycol as a solvent and l -ascorbic acid and oxalic acid as additives/surfactants respectively, without using water as solvent. Depending on the surfactant used, the morphology of the ZnO hierarchical nanostructures has changed dramatically which can be attributed to the reaction kinetics affected by presence of generated solvents, evolved gases. The structural analysis reveals the formation of wurtzite hexagonal crystalline structure. Electron microscopy images show the pomegranate and hollow sphere like morphology. The secondary nanoscale growth has been observed on the shell of pomegranate like ZnO microspheres. The synthesized ZnO hierarchial nanostructures have been used as photoanode in dye sensitized solar cells (DSSCs) which showed enhanced light harvesting properties than the commercial ZnO. Pomegranate like structure has displayed better light conversion efficiency (4.35%) as compared to ZnO hollow sphere structures (3.28%). This enhancement in photocurrent and power conversion efficiency could be due to interesting pomegranate like architecture of ZnO coupled with secondary 1-dimensional growth which provided more specific surface area for dye loading.

In our contemporary endeavor, metallic molybdenum (Mo) and semiconducting molybdenum trioxide $({\rm MoO}_{3})$ nanostructures have been simultaneously generated via solid state reaction between molybdenum (III) chloride $({\rm MoCl}_{3})$ and polyphenylene sulfide (PPS) at 285 $^{\circ}{\rm C}$ in unimolar ratio for different time durations, namely, 6 h, 24 h, and 48 h. The resultant nanocomposites (NCs) revealed formation of predominantly metallic Mo for all the samples. However, ${\rm MoO}_{3}$ gradually gained prominent position as secondary phase with rise in reaction time. The present study was intended to investigate the antibacterial potential of metal-metal oxide-polymer NCs, i.e., Mo- ${\rm MoO}_{3}$ -PPS against microorganisms, viz., Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, and Aspergillus fumigatus. The antibacterial activity of the NCs was evaluated by agar well diffusion investigation. Maximum sensitivity concentrations of NCs were determined by finding out minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC). Moreover, the NCs prepared at reaction time of 48 h exhibited best MBC values and were tested with time kill assay which revealed that the growth of S. aureus was substantially inhibited by Mo- ${\rm MoO}_{3}$ -PPS NCs. This synchronized formation of Mo- ${\rm MoO}_{3}$ nanostructures in an engineering thermoplastic may have potential antimicrobial applications in biomedical devices and components. Prima facie results on antifungal activity are indicative of the fact that these materials can show anti-cancer behavior.

ZnO shows promising candidature as photoanode material for dye-sensitized solar cells (DSSCs) due to its high bulk electron mobility and easily tailorable geometrical structures. The objective of this study is to facilitate the development of highly porous hierarchical ZnO for enhanced power conversion efficiency in dye-sensitized solar cells (DSSC) due to its greater dye adsorption. This study investigated the influence of reaction temperatures of 120 °C (sample Z-1) and 180 °C (sample Z-2) in hydrothermal synthesis on structural, morphological and optical properties of resultant ZnO nanostructures and their performance as photoanode material in DSSCs. The synthesized beaded nanochain bundles of ZnO, with multilayered and highly ordered texture, have diameters of several micrometers. Structural and morphological analysis shows that the ZnO beaded nanochain-like architectures possess wurtzite crystalline nature. These morphological improvements (beaded nanochains) of ZnO were found to exhibit higher dye loading and conversion efficiency due to increase in the surface area while reducing charge recombination. The maximum conversion efficiency was obtained with Z-1 and Z-2 is 2.95 and 3.56% with photocurrent of 7.73 and 9.24 mA/cm2, respectively. The obtained results pertaining to the DSSC performance studies were corroborated by the impedance spectroscopy data. Hierarchical beaded ZnO nanochains synthesized at different hydrothermal reaction temperatures of 120 and 180 °C were used as photoanode in DSSCs (probably for the first time) exhibited enhanced light harvesting characteristics (efficiencies of 2.95 and 3.56%, respectively) than the commercial ZnO.

This study focused on the effect of different reaction temperature on the morphology of zinc oxide. The temperature plays a significant role for the growth along different planes and axis. We synthesized ZnO hydrothermally at different temperature (60, 100, 140, and 180 °C). The synthesized ZnO nanopowders were characterized by UV–visible spectroscopy (UV–vis), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The absorption spectrum of ZnO nanoparticles was observed with excitonic peaks in the range 372 to 376 nm. The XRD patterns of the particles reveal the formation of hexagonal phase for ZnO with high degree of crystallinity. The FESEM images of ZnO powder shows the formation of nanobelts, nanoplates, and nanorods. As temperature was increased, the morphology of ZnO nanostructures changed from nanobelts to nanorods. The synthesized ZnO powders were successfully employed as electrode material in dye-sensitized solar cells to evaluate the photovoltaic performances of synthesized ZnO nanobelts, nanoplates, and nanorods.

Nanocomposites containing magnetic nanoparticles embedded in a polymer matrix with good thermal stability (up to 200°C) are technologically important. We report an environmentally benign solid–solid approach for synthesis of cobalt sulfide and its nanocomposite using a thermally stable matrix of polyphenylene sulfide. Physicochemical characterizations reveal the formation of nanoclusters of the hexagonal phase CoS. Even though bulk CoS is nonmagnetic, magnetization studies exhibit anomalous magnetic behavior for phase-pure nanoscale CoS and its nanocomposites.

To facilitate in situ generation of single and mixed-phase molybdenum oxide on the nanoscale in a network of polyphenylene sulfide (PPS), a novel polymer–inorganic solid-state reaction is proposed. Ammonium molybdate was homogeneously mixed with PPS in 1:1 molar ratio and heated at 285°C for different times (6 h, 24 h, or 48 h) under ambient conditions. The products were characterized by x-ray diffractometry, field emission scanning electron microscopy, and transmission electron microscopy. Structural investigations revealed the co-existence of mix-phased molybdenum oxide, i.e. dominant orthorhombic α-MoO3, and minor monoclinic Mo8O23 phases, within the modified PPS matrix. The resulting molybdenum oxide nanostructures had rod and sheet-like morphology in the PPS matrix. Dielectric measurements on pellets prepared from the resulting nanocomposites revealed improvement of the dielectric properties compared with values reported for pure PPS. The resulting nano-composites may exhibit properties synergistically derived from those of their components (molybdenum oxide and PPS), i.e. lower dielectric constant and loss tangent, enabling application as relatively high-temperature capacitors.

Herein, we report the synthesis of metallic molybdenum microspheres and hierarchical MoS2 nanostructures by facile template-free solvothermal and hydrothermal approach, respectively. The morphological transition of the Mo microspheres to hierarchical MoS2 nanoflower architectures is observed to be accomplished with change in solvent from ethylenediamine to water. The resultant marigold flower-like MoS2 nanostructures are few layers thick with poor crystallinity while spherical ball-like molybdenum microspheres exhibit better crystalline nature. This is the first report pertaining to the synthesis of Mo microspheres and MoS2 nanoflowers without using any surfactant, template or substrate in hydro/solvothermal regime. It is opined that such nanoarchitectures of MoS2 are useful candidates for energy related applications such as hydrogen evolution reaction, Li ion battery and pseudocapacitors. Inquisitively, metallic Mo can potentially act as catalyst as well as fairly economical Surface Enhanced Raman Spectroscopy (SERS) substrate in biosensor applications.

The pulse laser ablation is a simple and direct method used for the generation of nanostructures in liquid environment. In this paper, formation of tungsten sulfide [Formula: see text] nanostructures has been carried out using nanosecond (ns) and femtosecond (fs) laser ablation with ablation time 120 min. In addition, the field emission studies were performed of the prepared sample. The characterization techniques such as the transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-visible spectroscopy have been used to confirm the surface morphology as well as structural details. It is observed that the laser pulse regime plays a vital role on the size reduction of [Formula: see text] nanostructure. The X-ray spectra reveal the formation of [Formula: see text] nanoparticles for ns laser ablation, while [Formula: see text] nanosheets for fs laser ablation. The TEM images indicate that the transformation of [Formula: see text] microsheet into nanosheet of the size about 15–200 nm for the sample treated with ns laser and fs laser ablation. Also, the results clearly shows the improvement in the field emission characteristics for laser ablated [Formula: see text] nanosheets. The enhanced field emission characteristics is attributed to the formation and separation of few layer [Formula: see text] nanosheets. The [Formula: see text] nanostructures may have great potential for the applications in optoelectronic devices.

At present, there is considerable interest in polymer-metal chalcogenides/oxides based nano-composites on account of their tunable optical, magnetic, electronic and catalytic properties. Here in, we report a simple single step approach for the in-situ synthesis of combined cobalt sulphide/cobalt oxide in polyphenylenesulphide (PPS) polymer matrix. We have illustrated the suitability of this methodology by reacting commonly available cobalt precursors with engineering thermoplastic, PPS. The cobalt precursor was homogeneously mixed with PPS in the molar ratios of 1:1, 1:5, 1:10, 1:15, respectively, followed by heating the mixtures obtained at the melting temperature of the polymer (285?C) for six hours. The resultant products were characterized by X-ray Diffractometry (XRD), Field-Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscope (HRTEM), Diffuse Reflectance Spectroscopy (DRS) technique and Fourier Transformation Infra red Spectroscopy (FTIR). Formation of mixed phases viz., sulphide and oxide of cobalt within modified PPS matrix was confirmed by XRD. The resultant nanoparticles of cobalt sulphide and cobalt oxide embedded in the PPS matrix showed crooked and chunk morphology. The optical properties of the resultant nanocomposites indicate the shift in the absorption hump due to nanoscale size effect.

We, herein, report the antimicrobial properties of uncapped silver nanoparticles for a Gram positive model organism, Bacillus subtilis. Uncapped silver nanoparticles have been prepared using less-explored DC arc thermal plasma technique by considering its large scale generation capability. It is observed that the resultant nanoparticles show size as well as optical property dependent antimicrobial effect.

We herein report the feasibility of polymer-inorganic solid-state reaction route for simultaneous in situ generation of Ag & Ag2S nanostructures in polymer network wherein an engineering thermoplastic, polyphenylene sulphide (PPS), itself acts as a chalcogen source as well as a stabilizing matrix for the resultant nanoproducts. Typical solid-state reaction was accomplished by simply heating the physical admixture of the two reactants i.e. AgNO3 and PPS by varying molar ratios mainly 1:1, 1:5, 1:15, 1:20, at the crystalline melting temperature (285 °C) of PPS. The synthesized nanoparticles were characterized by various physico-chemical techniques like X-ray Diffractometry, Scanning Electron Microscopy equipped with EDAX, Transmission Electron Microscopy and UV-Visible spectroscopy. The prima facie observations suggest the effective formation and subsequent entrapment of mainly nanocrystalline metallic silver (fcc) in PPS matrix for all the molar ratios chosen for the reaction. Additionally, simultaneous occurrence of nanocrystalline Ag2S (monoclinic phase) is also noticed in case of heated admixture of AgNO3: PPS with equimolar ratio. The TEM analysis reveals nanoscale polydispersity (5nm to 70nm) and prevalence of mainly spherical morphological features in all the cases with occasional indications of triangular and hexagonal morphological features depending upon the reaction molar ratio.

An efficient modified arc plasma method, where a focusing electric field is superimposed on the arc electric field, is optimized for the bulk generation of highly pure multi-walled carbon nanotubes. Raman spectroscopy and thermogravimetric measurements have been used to optimize the process.

Thin films of CdS have been prepared by chemical spray pyrolysis by spraying precursor solution directly onto soda lime glass (SLG) substrates. Influence of substrate temperature on structural, optical, morphological and electrical properties have been investigated by using various techniques such as low angle X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), UV–visible spectroscopy photoluminescence (PL) spectroscopy etc. Formation of CdS has been confirmed by low angle XRD, Raman spectroscopy and XPS analysis. XRD pattern showed that CdS films are polycrystalline, have hexagonal structure and prefer orientation of crystallites shifts from (101) to (002) with increase in substrate temperature. Raman spectroscopy revealed that exciton-phonon coupling depends on substrate temperature and hence on crystallite size. Optical band gap increased from 2.43 to 2.99 eV when substrate temperature increased from 325 to $475\,^\circ {\rm{C}}$. Transmittance of the film also showed an increasing trend from $\sim 52 \% $ to $\sim 80 \% $ with increase in substrate temperature. Such high band gap and transmittance values of CdS films prepared at $475\,^\circ {\rm{C}}$ make it a useful window material in CdS/CdTe and CdS/Cu2S heterojunction solar cells.

The incessant use of antibiotics against infectious diseases has translated into a vicious circle of developing new antibiotic drug and its resistant strains in short period of time due to inherent nature of micro-organisms to alter their genes. Many researchers have been trying to formulate inorganic nanoparticles-based antiseptics that may be linked to broad-spectrum activity and far lower propensity to induce microbial resistance than antibiotics. The way-out approaches in this direction are nanomaterials based (1) bactericidal and (2) bacteriostatic activities. We, herein, present hitherto unreported observations on microbial abatement using non-cytotoxic molybdenum disulfide nanostructures (MSNs) which are synthesized using microwave assisted solvothermal route. Inhibition of biofilm formation using MSNs is a unique feature of our study. Furthermore, this study evinces antimicrobial mechanism of MSNs by reactive oxygen species (ROS) dependent generation of superoxide anion radical via disruption of cellular functions.

Herein we report an extremely simple one-pot synthesis of lead sulphide nanorods inside the engineering thermoplastic (i.e. polyphenylene sulphide) which plays a dual role of stabilizing matrix as well as a chalcogen source. The effect of molar ratios of the reactants on the morphology of the samples was studied. The prima facie observations suggest the effective formation of 1-D PbS nanorods along with cubic lead as an impurity phase. The average aspect ratio is found to be approximately 4 to 42 depending upon the reactant molar ratio.

The present work describes the preliminary results on large-scale synthesis and characterisation of copper (Cu) and aluminium nitride (AlN) nano powders by transferred arc thermal plasma technique. The transferred arc was used to vaporise the precursor materials (Cu, Al metal 99.9% pure). Nano particles are formed in the gas phase as a result of homogeneous nucleation. The vapours of Al were allowed to react with NH3 gas for the synthesis of AlN. Rapid quenching using Ar/N2 then produced the desired nano powders. For the generation of Cu nano powders, argon was used as a quench gas. The resultant nano-powders of Cu, AlN were collected under the controlled atmosphere. TEM and AFM results show the particle size ranging between 70 nm and 100 nm. These particles possess exotic applications in defence systems, armour for aircraft and vehicles, aeronautical systems, power electronics, microelectronics etc.

Uncapped silver nanoparticles were synthesised using hitherto unexplored DC arc thermal plasma technique using Ar, He and mixture of Ar and He as plasma gases. Effect of change in plasma gases on the morphological properties of synthesised nanoparticles has been studied. XRD revealed formation of phase pure cubic silver. TEM study disclosed formation of nanoparticles with size in the range of 20-50 nm and 5-30 nm for silver nanopowders synthesised with He and Ar as plasma gases, respectively while a bimodal size distribution with sizes ranging from ∼20 nm to 150 nm is observed for silver nanopowders synthesised with mixture of He and Ar as plasma gases in 2 : 3 ratio. UV-visible spectroscopy results also support the wide particle size distribution. Demixing effect is presumably responsible for increase in particle size and wide variation in particle size distribution in case of nanoparticles synthesised using mixed gas plasmas.