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A simple, efficient and economically viable method for the Heck reaction has been accomplished in the absence of phosphine ligand. The Heck reaction was performed using nanostructured Ni-Co/ZnO material as a heterogeneous catalyst in a DMF/H2O solvent system and in the presence of K2CO3, at 120 °C. The Ni-Co/ZnO nanostructures were prepared by the facile reduction-impregnation method. The structural and morphological properties of Ni-Co/ZnO nanostructure were investigated using various physico-chemical characterization techniques. Structural studies displayed the formation of hexagonal (wurtzite) ZnO. Electron microscopy imaging showed the presence of agglomerated clusters of Ni-Co nanoparticles over the surfaces of elliptical, flower bud-like and irregularly shaped sub-micron sized particle bundles of ZnO. The elemental composition analysis (EDX) confirmed the loading of Ni and Co nanoparticles over the nanocrystalline ZnO. The surface chemical state analysis of Ni-Co/ZnO material validated that Ni nanostructure exists in Ni2+ and Ni3+ species, whereas, Co nanostructure exists in Co2+ and Co3+ species. UV–Vis diffuse reflectance spectroscopy displays red shift in the light absorption edge of Ni-Co/ZnO catalyst compared to pure ZnO. The as-prepared Ni-Co bimetallic supported ZnO nanostructure showed better catalytic activity and stability for the Heck reactions under phosphine ligand-free conditions. Ni-Co/ZnO catalyzed Heck reactions afforded the corresponding cross-coupled products with moderate to good yields (up to 92%). Ni-Co/ZnO catalyst could be reused for five successive runs without significant loss of catalytic activity.

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.

In the present study, we have demonstrated a unique approach for the synthesis of nanostructured ternary metal sulphides, XIn2S4 (X = Cd, Zn), using a simple, template free and low temperature solid phase reaction. A stoichiometric amount of precursors including CdO/ZnO, In2O3 and thiourea were mixed homogeneously and heated at 150 °C for different time intervals to produce nanostructured XIn2S4. Various molar ratios of the precursors were tried and among the different ratios, the molar ratio of 1 : 1 : 8 was found to be optimum for the growth of phase pure nano crystalline XIn2S4. X-ray analysis confirms the formation of cubic spinel Cadmium Indium Sulfide (CdIn2S4) and hexagonal Zinc Indium Sulfide (ZnIn2S4). HRTEM analysis confirms the formation of nanostructures of XIn2S4 with spherical and rod like mixed morphology. The band gap of the as synthesized materials is within the visible region i.e. 2.25 and 2.6 eV for CdIn2S4 and ZnIn2S4, respectively. Therefore, the activity of both the photocatalyts was tested for hydrogen generation by H2S and H2O splitting under natural solar light. The ZnIn2S4 photocatalyst was found to be more active for both H2S and H2O splitting reactions with H2 evolution rates of 6994 μmol h−1 g−1 and 243 μmol g−1, respectively, whereas for CdIn2S4 the rates were found to be 6128 μmol h−1 g−1 and 128.4 μmol g−1, respectively. The H2 evolution rate by H2S splitting was found to be much higher than various previously reported nanostructured photocatalysts. The simple, environmentally friendly and cost effective method reported herein can be applied for the large scale synthesis of XIn2S4 nanoparticles, which is the novelty of the present work.

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.

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.

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.

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.

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.

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.

We herein propose a facile single-step approach involving solid-state reaction between silver salt and engineering thermoplastic polyphenylene sulfide for simultaneous in situ generation of nanosca...

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.

1-D nanorod bundles as well as sea urchin and starfish like hierarchical morphological nanoarchitectures of CdS have been synthesised using a facile microwave assisted hydrothermal/semi-solvothermal technique. Observation of interesting regular/irregular pine-tree like secondary growth over these hierarchical nanoarchitectures is an important aspect of this work. Cadmium acetate and thiourea were used as precursor materials and were dissolved in solution containing mixture of diethylene triamine (DETA) and deionised water (DIW) in different volume ratios prior to subjecting the resultant solution to microwave radiation of 300 W at a reaction time of 10 min and temperature of 140°C. XRD revealed formation of hexagonal CdS with strong (002) preferred orientation (c-axis orientation). Morphology dependent optical properties are studied using room temperature photoluminescence spectroscopy. We feel such secondary growth will be highly favourable in determining the non-linear properties of optoelectronic devices fabricated using such novel hierarchical nanoarchitectures.