Nanostructured Materials for Energy Applications

Using the hybrid nanostructure and asymmetric configuration as strategies to enhance the capacitance of ZnO is demonstrated. A novel CNO-ZnO nanocomposite with unique nanoporous microstructure is used to achieve superior electrochemical performance in an asymmetric configuration. The nanoporous morphology with well dispersed ZnO surface sites results in enhanced electrochemical activity through better electron transport and improved electrolyte accessibility in the nanocomposite. A binder-free, flexible asymmetric supercapacitor with nanoporous CNO-ZnO as negative and ZnO as positive is demonstrated to achieve high electrochemical performance. For the first time, an optimized CNO-ZnO//ZnO flexible asym-metric supercapacitor (ASC) is demonstrated in a stable operation voltage window of 1.8 V with a high energy and power density of 10 Wh/kg and 8100 W/kg, respectively. Furthermore, the CNO-ZnO//ZnO ASC device exhibits excellent long cycle life with retention of 92% specific capacitance after 2000 cycles. The overall device performance is attributed to their unique nanoporous microstructure, stable interface formation and interactive effect of constituent phases in the nanocomposite. From the overall findings, ZnO composites with carbon nano onions (CNO) can be a viable and potential choice for supercapacitor applications.

Nanocomposites have gained much importance in different fields, commercially and technologically, due to the possibilities in tuning the properties of nanocomposites. In the present work, vanadium oxide (V 2 O 5)/tin oxide (SnO 2) nanocomposites were synthesized using simple sol-gel method. Two independent experiments were carried out to synthesis the V 2 O 5 /SnO 2 nanocomposites. The V 2 O 5 /SnO 2 nanocomposites were prepared from the precursors of tin chloride, ammonium metavanadate and ethanol (Experiment 1). A few ml of concentrated hydrochloric acid (HCl) was added in the precursors with and V 2 O 5 /SnO 2 nanocomposites were prepared (Experiment 2) using ethanol as a solvent. Effect of HCl on the modifications of structural, morphological and optical properties of the V 2 O 5 /SnO 2 nanocom-posites was studied. Coexistence of V 2 O 5 and SnO 2 phases was confirmed by the X-ray diffraction studies. Thermogravimetric analysis (TGA) shows the stability of the as-synthesized V 2 O 5 /SnO 2 nanocomposites from 350 • C. The crystallinity and the surface morphology of the synthesized V 2 O 5 /SnO 2 nanocomposites were improved effectively due to addition of HCl in the preparation of the precursor solution. UV-DRS absorption spectra showed that the absorbance is modified and the band gap is decreased with increase in crystallite size due to the addition of HCl. The predominant Raman peaks at 140 cm −1 and 991 cm −1 confirm the presence of orthorhombic V 2 O 5 phase. Further, the addition of HCl in the preparation of precursor solution revealed marked difference in the surface morphology of the nanocomposites.

Mesoporous TiO 2 nanoparticle films are used as photoanodes for high-efficiency dye-sensitized solar cells (DSCs). In spite of excellent photovoltaic power conversion efficiencies (PCEs) displayed by titanium dioxide nanoparticle structures, the transport rate of electrons is known to be low due to low electron mobility. So the alternate oxides, including ZnO, that possesses high electron mobility are being investigated as potential candidates for photoanodes. However, the PCE with ZnO is still lower than with TiO 2 , and this is typically attributed to the low internal surface area. In this work, we attempt to make a one-to-one comparison of the photovoltaic performance and the electron transfer dynamics involved in DSCs, with ZnO and TiO 2 as photoanodes. Previously such comparative investigations were hampered due to the morphological differences (internal surface area, pore diameter, porosity) that exist between zinc oxide and titanium dioxide films. We circumvent this issue by depositing different thicknesses of these oxides, by atomic layer deposition (ALD), on an arbitrary mesoporous insulating template and subsequently using them as photoanodes. Our results reveal that at an optimal thickness ZnO exhibits photovoltaic performances similar to TiO 2 , but the internal electron transfer properties differ. The higher photogenerated electron transport rate contributed to the performances of ZnO, but in the case of TiO 2 , it is the low recombination rate, higher dye loading, and fast electron injection.

Various Mn-doped ZnS controlled nanostructures were synthesized directly on the nickel foam to develop a binder-free, high-performance positive electrode for supercapacitors, where specific energy, specific power, and cycling stability are the crucial parameters. We achieved Mn-doped ZnS based different nanostructures, such as nanosheets, nanoflakes, and nanoneedles just by monitoring the reaction temperature. Among those three morphologies, the nanosheets showed the highest specific capacitance of 1905 F g −1 at a current density of 1 A g −1 and 93.1% capacity retention after 10,000 cycles in a three-electrode system. An asymmetric supercapacitor (ASC) device was assembled using Mn-doped ZnS nanosheets and activated carbon as a positive and negative electrode, respectively. The ASC device showed a high capacitance of 140 F g −1 (210 C g −1), delivered a high specific energy of 43.3 Wh kg −1 , and a high specific power of 6.8 kW kg −1. The ASC device retained 93.3% with excellent coulombic efficiency of 95.7% after 8,000 cycles. Importantly, two serially connected ASC devices illuminated 52 red light-emitting diodes. This highlights the potential of the Mn-doped ZnS based ASC device for the next generation supercapacitors.

TiO 2 -based photocatalyst layers are still highly favored materials for photocatalysis on immobilized semiconductor electrodes because of their favorable electronic band positions, high corrosion stability, cost efficiency, and readily available titanium. Since chemical synthesis of nanocrystalline TiO 2 layers from alkoxide precursors is usually complex and of low reproducibility, new methods are required to enable large-scale production of immobilized titania catalyst layers for practical applications. The synthesis of TiO 2 -layers on fluorine doped tin oxide (FTO) by means of a reactive sputtering process is reported here, with stable operation being implied by the means of a λ-sensor. Structural, electrochemical, and photocatalytic properties were investigated for different layer thicknesses and postdeposition annealing temperature of the deposited TiO 2 by means of SEM, TEM, XRD, XPS, UV/vis spectroscopy, and a range of photochemical measurements including iE curves, acIS, IMVS and IMPS, and IPCE.

The clean energy storage and fast delivery during the demand for sudden power applications encourage us to synthesize highly graphitic carbon nano-onions (CNOs) using a simple, one-step synthesis protocol. The as-synthesized CNOs demonstrate an excellent electrochemical property without employing any post-synthesis harsh chemical treatments and purifications. The integration of CNOs with the polyaniline (PANI) by the in-situ oxidative polymerization of the aniline monomer shows noticeable enhancement in the PANI's overall electrochemical performance. PANI/CNO heterostructure exhibits a maximum deliver-able specific capacitance of 196 F g −1 at the current density of 1 A g −1. Notably, the energy and power densities also show enhancement for the heterostructure. In the hybrid heterostructure, CNO effectively improves the electronic conductivity, lessens the PANI fibers' agglomeration, and generates a larger active surface for the electrolytic ion interactions. Simultaneous contribution and synergistic effect from the CNO and the PANI lead to the coexistence of both electric double layer and pseudocapacitive specific capacitance in the nanocomposite. Favorable mesoporous structure with uneven surface contributed by incorporating CNOs results in enhanced wettability and shorter ion diffusion path in the PANI/CNO electrode. The successful integration of CNO into PANI augmented the capacitive performance of the device effectively.

Structural, optical and light detection properties on carbon-nanotube-modified ZnO thin films grown at various temperatures from room to 1173 K are investigated. The optical band gap values calculated from reflectivity data show a hump at a critical temperature range of 873-1073 K. Similar trends in surface roughness as well as crystallite size of the films are observed. These changes have been attributed to structural change from wurzite hexagonal to cubic carbon modified ZnO as also validated by x-ray diffraction, RBS and PIXE of these layers. UV and visible light detection properties show similar trends. It is demonstrated that the present films can sense both UV and visible light to a maximum response efficiency of 66 % which is much higher than the last reported efficiency 10 %. This high response is given predominantly by cubic crystallite rather than the wurzite hexagonal composites.

Rapid annealing (4–10 s) induced primary crystallization of soft magnetic Fe–Si nanocrystals in a Fe73.5Si15.5Cu1Nb3B7 amorphous alloy has been systematically studied by atom probe tomography in comparison with conventional annealing (30–60 min). It was found that the nanostructure obtained after rapid annealing is basically the same, irrespective of the different time scales of annealing. This underlines the crucial role of Cu during structure formation. Accordingly, the clustering of Cu atoms starts at least 50 C below the onset temperature of primary crystallization. As a consequence, coarsening of Cu atomic clusters also starts prior to crystallization, resulting in a reduction of available nucleation sites during Fe–Si nanocrystallization. Furthermore, the experimental results explicitly show that these Cu clusters initially induce a local enrichment of Fe and Si in the amorphous matrix. These local chemical heterogeneities are proposed to be the actual nuclei for subsequent nanocrystallization. Nevertheless, rapid annealing in comparison with conventional annealing results in the formation of 30% smaller Fe–Si nanocrystals, but of identical structure, volume fraction and chemical composition, indicating the limited influence of thermal treatment on nanocrystallization, owing to the effect of Cu.

The hybrid structure of Fe2O3 nanoparti-
cles/TiO2 nanofibers (NFs), combines the merits of
large surface areas of TiO2 NFs and absorption in
ultraviolet light–visible light range. This structure can
be used for many applications such as photoelectro-
chemical water splitting and photo-catalysis. Here, a
sol-flame method is used for depositing Fe2O3 on TiO2
NFs that were prepared by hydrothermal on Ti sheets.
The obtained materials were characterized by XRD,
SEM, UV/Vis diffuse reflectance, Raman, and XPS.
The results revealed the formation of rutile and anatase
crystalline phases together with Fe2O3. This process
moves the absorption threshold of TiO2 NFs support
into visible spectrum range and enhances the photo-
current in comparison to bare TiO2 NFs, although no
hole scavenger was used. The impedance measure-
ment at low and high frequencies revealed an increase
in series resistance and a decrease in resistance of
charge transfer with sol-flame treatment time. A
mechanism for explaining the charge transfer in these
TiO2 NFs decorated with Fe2O3 nanoparticles was
proposed.

Generally, platinum (Pt) is used as a counter electrode (CE) for triiodide (I3

) reduction in the electrolyte
solution of dye-sensitized solar cell (DSSC). Unfortunately, the high cost and scarcity of Pt make the
limitation for large scale production of DSSCs. Hence, to replace Pt, we have prepared the titanium
carbide (TiC) embedded carbon nanofibers (CNFs) by a facile electrospinning technique and used as a low
cost alternative CE for DSSCs. The TiC embedded CNFs are found to have an enhanced electrocatalytic
activity towards the I3
– to iodide (I–) reduction and lower charge transfer resistance. The photovoltaic
performance shows that the DSSC fabricated using TiC (10 wt%) embedded CNFs as CE has very closer
photo-conversion efficiency than std. Pt. This is attributed to the synergistic effect of TiC with larger
electrocatalytic surface area of CNFs which plays a substantial part in the improvement of photovoltaic
performance of DSSC.

Chemical flooding is of increasing interest and importance due to high oil prices and the need to increase oil production. Research in nanotechnology in the petroleum industry is advancing rapidly, and an enormous progress in the application of nanotechnology in this area is to be expected. The nanotechnology has been widely used in several other industries, and the interest in the oil industry is increasing. Nanotechnology has the potential to profoundly change enhanced oil recovery and to improve mechanism of recovery, and it is chosen as an alternative method to unlock the remaining oil resources and applied as a new enhanced oil recovery method in last decade. This paper therefore focuses on the reviews of the application of nanotechnology in chemical flooding process in oil recovery and reviews the applications of nanomaterials for improving oil recovery that have been proposed to explain oil displacement by polymer flooding within oil reservoirs, and also this paper highlights the research advances of polymer in oil recovery. Nanochemical flooding is an immature method from an application point of view.

Magnetic properties of some nanocrystalline soft magnetic alloys are evaluated by means of a model obtained from literature. The
influence of alloy elements in grain diameter, crystalline fraction and anisotropies are investigated in order to obtain information for the
design of nanocrystalline soft magnetic materials. The study concerns materials with nanocrystalline composition of Fe, Fe-Si, Fe-Si-Al,
and Fe-Ge, and is complemented with alloys containing nanocrystals of Fe and Fe-Co from literature. Results indicate that the reduction
of grain diameter in Fe-based nanocrystal alloys is themain challenge to enhance the soft magnetic properties, when induced anisotropies
are suppressed. For Fe-(Si,Al,Ge)-based nanocrystals, it is necessary to obtain a good balance of the magnetoelastic anisotropies. This
can be achieved by modifying the amount of crystallized fraction via changes in the chemical composition of the nanocrystals and/or the
matrix. In the case of Fe-Co, magnetic softness is attained by decreasing the Co content or with the addition of elements like Si or Al.

The focus of research work is to minimize the solid waste and increase the resources of energy generation. It means solid waste management is very necessary for human beings at the modern time. We are done this process in our collage and we are used the garden waste of our collage parks. In our university, we have a large area for gardening purpose. Which a huge amount of gardening waste is generated. Typically, the garden refuse stream consists of a wide range of putrescible material including leaves, grass-clippings, perennial and annual plant material, tree and shrub branches and other woody waste, etc. We can use this waste for the production of bio gas. . There was a digester tank of 20 liter for decomposition of mixture of cow dung slurry and garden waste. Sugarcane thresh was also added for increase the production of bio gas like as additives. The garden waste was grinding by the grinder machine properly. Then, this mixture is putting for the 30 days. And then, we are seeing that tube is fully filled by the gas. The result is observed that production of biogas is mainly depended on the parameters like-pH value, temperature etc. if the pH value is approximately 7 or 7.5 , then the productivity of bio gas is also increased. So, we can maintain the pH value by the use of additives and also increase the bio gas production. And, we shall use the high temperature for this process. Because, the high temperature is increased the rate of decomposition of mixture of slurry. We are measured this parameters at the time of influent and effluent of slurry like as -temperature, pH value, total solids , volatile solids and non-volatile solids etc. The pH value of influent is 7.5 and of effluent is 5.85. And the temperature of influent is 29 0 C and of effluent is 32 0 C . These values are measured throughout the time of experimentation. This type of biogas comprises primarily methane and carbon dioxide. Bio gas production requires anaerobic digestion. My research work was to create biogas which will be more cost effective, eco-friendly, cut down on landfill waste, generate a high-quality renewable fuel, and reduce carbon dioxide & methane emissions. It is a technology for green environment and zero wastage and produces the huge amount of energy sources.

2D Cu-Ni-Co ternary oxide nanoflakes from 1D long leaf arrays were prepared using a simple, cost-effective, environmentally friendly hydrothermal approach, followed by heat treatment in air, and their supercapacitive performance was investigated. The binder-free 2D Cu-Ni-Co oxide nanoflakes electrode possessed an outstanding specific capacitance of 2615 F g − 1 (1046 C g − 1) at a current density of 1 A g − 1 as well as excellent rate capability and high capacitance retention of 88% at a high current density of 10 A g − 1 in a three-electrode configuration. A hybrid supercapacitor device exhibited a high specific capacity of 185 C g − 1 at 1 A g − 1 and high capacitance retention of 90.2% after 10,000 cycles. Additionally, the hybrid supercapacitor device delivered high specific energy of 51 Wh kg −1 at a specific power of 764 W kg −1. The attractive electrochemical performance of Cu-Ni-Co oxide makes this a promising electrode material for practical supercapacitor applications .

Abstract Owing to the existence of periodic channels in phosphorene, this 2D material can be a good candidate for room temperature reversible hydrogen storage. The density functional theory calculations (DFT), including van der Waals interactions (vdW-DF2) coupled with the cooper exchange functional (C09), has been applied to study the potential of phosphorene as a new 2D material for hydrogen storage. Our results show that the adsorption energy (−292 to −277 meV) of H2 on phosphorene is appropriate for storage. The analysis of diffusion pathways between different physisorbed states on phosphorene shows that a single hydrogen molecule diffuses very easily along the open channel (less than 1 meV along the zigzag direction), as compared to 14 meV for diffusion across the channels (along the armchair direction). The potential energy surfaces for the dissociative chemisorption of H2 was computed on highly symmetric sites of phosphorene and the highest activation barrier was found to be 2.77 eV. The very large dissociation energy coupled with a strong physisorption of H2 on phosphorene and facile diffusion, makes this 2D material a promising candidate for H2 storage at room temperature.

ABSTRACT Growth conditions, structural, and optical properties of MgO nanostructure have been investigated. Surface composition and shift in binding energy of Mg at 50.8 eV due to oxidation were examined by core-level spectroscopy. The SEM showed that the film is dense, and grain growth and crystallinity are enhanced by post-deposition annealing. Grain distribution was appraised within the confinement of 24.51 µm2 from the selected scan areas. X-ray diffraction studies indicated prominent peaks, which are attributed to (111), (200), and (220) reflections from fairly crystallized and randomly oriented MgO thin film. Plane (111) is found to be the preferred orientation of the film. The film transmitted well across the visible spectrum and the estimated energy band gap is 5.41 eV. Absence of catalyst in the electrolyte solution aided the purity of the sample. Copyright © 2014 John Wiley & Sons, Ltd.

Copper tin sulphide (Cu 2 SnS 3, CTS) is a promising p-type thermoelectric material. In the present work, we have investigated the cation disorder in CTS disks made by sintering powders produced via high energy reactive ball-milling. The crystalline structures, electronic and thermal properties were systematically investigated. As-milled CTS shows a disordered cubic structure (c-CTS), preserved with thermal treatment up to 500 C. By increasing the thermal treatment temperature, CTS gradually evolves towards the ordered monoclinic structure (m-CTS), reaching complete order at 650 C. The disordered CTS has several times higher zT than the ordered CTS. In fact, ordered CTS has high thermopower, up to 700 mV/K, and high electrical resistivity leading to zT < 0.05 above 700K; whereas, disordered (c-CTS) has comparatively high zT~0.30 above 700K. This has been related to the lower electrical resistivity, and the ultra-low thermal conductivity (k~0.26 W/m-K), resulting from the disorder...

Abstract Owing to the existence of periodic channels in phosphorene, this 2D material can be a good candidate for room temperature reversible hydrogen storage. The density functional theory calculations (DFT), including van der Waals interactions (vdW-DF2) coupled with the cooper exchange functional (C09), has been applied to study the potential of phosphorene as a new 2D material for hydrogen storage. Our results show that the adsorption energy (−292 to −277 meV) of H2 on phosphorene is appropriate for storage. The analysis of diffusion pathways between different physisorbed states on phosphorene shows that a single hydrogen molecule diffuses very easily along the open channel (less than 1 meV along the zigzag direction), as compared to 14 meV for diffusion across the channels (along the armchair direction). The potential energy surfaces for the dissociative chemisorption of H2 was computed on highly symmetric sites of phosphorene and the highest activation barrier was found to be 2.77 eV. The very large dissociation energy coupled with a strong physisorption of H2 on phosphorene and facile diffusion, makes this 2D material a promising candidate for H2 storage at room temperature.

Defects such as planar faults in thermoelectric materials improve their performance by scattering phonons with short and medium mean free paths (3-100 nm), thereby reducing the lattice thermal conductivity, k l. Understanding statistically the microscopic distribution of these extended defects within the grains and in low angle grain boundaries is necessary to tailor and develop materials with optimal thermoelectric performance for waste heat harvesting. Herein, we analyze these defects from the millimeter down to the nanometer scale in a AgSbTe 2 thermoelectric material with low angle grain boundaries. The investigations were performed using electron channeling contrast imaging combined with transmission electron microscopy. The microstructure study was complemented by estimating the effect of planar faults on the phonon scattering using the Debye-Callaway model. AgSbTe 2 is a promising thermoelectric material, which exhibits extremely low thermal conductivity, k, of 0.5 Wm À1 K À1 at room temperature. In contrast to conventional alloys or intermetallic materials, in the present material small angle grain boundaries are not composed of individual dislocations but of a dense arrangement of stacked planar faults with fault densities up to N PF ¼ 1:6,10 8 m À1. We explain their abundance based on their low interfacial energy of about 186 mJm À2 calculated ab-initio. The current findings show, that it is possible to reach very high densities of phonon-scattering planar faults by the correct microstructure engineering in AgSbTe 2 thermoelectric materials.

A twinned microstructure is frequently observed after a martensitic phase transition. In this paper we investigate the atomic-level processes associated with the twin formation in a model system, using a many-body potential parametrized to represent zirconium. Molecular-dynamics simulations of the martensitic phase transition from bcc to hcp in zirconium show the evolution of a laminated twinned microstructure. Plastic deformation also occurs, creating basal stacking faults. The plastic deformation is such as to cause a rotation of the twins. This alters the twinning angle to the 61.5° angle of the low-energy (1011)hcp twins. These are thus identified as a cause of microscopic irreversibility in the transition.

Copper tin sulphide (Cu2SnS3, CTS) is a promising p-type thermoelectric material. In the present work, we have investigated the cation disorder in CTS disks made by sintering powders produced via high energy reactive ball-milling. The crystalline structures, electronic and thermal properties were systematically investigated. As-milled CTS shows a disordered cubic structure (c-CTS), preserved with thermal treatment up to 500 °C. By increasing the thermal treatment temperature, CTS gradually evolves towards the ordered monoclinic structure (m-CTS), reaching complete order at 650 °C. The disordered CTS has several times higher zT than the ordered CTS. In fact, ordered CTS has high thermopower, up to 700 μV/K, and high electrical resistivity leading to zT

Copper tin sulphide (Cu 2 SnS 3, CTS) is a promising p-type thermoelectric material. In the present work, we have investigated the cation disorder in CTS disks made by sintering powders produced via high energy reactive ball-milling. The crystalline structures, electronic and thermal properties were systematically investigated. As-milled CTS shows a disordered cubic structure (c-CTS), preserved with thermal treatment up to 500 C. By increasing the thermal treatment temperature, CTS gradually evolves towards the ordered monoclinic structure (m-CTS), reaching complete order at 650 C. The disordered CTS has several times higher zT than the ordered CTS. In fact, ordered CTS has high thermopower, up to 700 mV/K, and high electrical resistivity leading to zT < 0.05 above 700K; whereas, disordered (c-CTS) has comparatively high zT~0.30 above 700K. This has been related to the lower electrical resistivity, and the ultra-low thermal conductivity (k~0.26 W/m-K), resulting from the disordered structure, promoting Phonon-Glass-Electron-Crystal (PGEC) characteristics. In our best knowledge, zT~0.30 above 700K is the highest in CTS samples without acting on the chemistry of the system.

The primary purpose of this study was to observe the effects of graphene doping on the structure and the physical properties of n-type thermoelectric materials. Structural characterizations of the produced materials were measured by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spec-troscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR). Temperature-dependent thermal conductivity and the Seebeck coefficient measurements were applied via physical properties measurement system (PPMS). After XRD analyses, the diffractograms showed that the produced materials had crystalline forms. With respect to observing SEM micrographs, the homogenization of the samples usually increased with graphene doping. The results of temperature-dependent thermal conductivity and the Seebeck coefficient measurements revealed that graphene doping had a positive influence on both values.

Nanocomposites of linear chain of ferroelectric-ferromagnetic crystal structure is considered. It is analyzed theoretically in the motion equation method on the pursuit of magnonic excitations,lattice vibration excitations and their interactions leading to a new collective mode of excitations,the electormagnons. In this particular work, it is observed that the magnetizations and polarizations are tunable in a given temperature ranges for some specific values of the coupling order parameter.