Incorporation of metallic nanoparticles (NPs) in polymer matrix has been used to enhance and control dissolution and release of drugs, for targeted drug delivery, as antimicrobial agents, localized heat sources, and for unique optoelectronic applications. Gold NPs in particular exhibit a plasmonic response that has been utilized for photothermal energy conversion. Because plasmonic nanoparticles typically exhibit a plasmon resonance frequency similar to the visible light spectrum, they present as good candidates for direct photothermal conversion with enhanced solar thermal efficiency in these wavelengths. In our work, we have incorporated ∼3-nm-diameter colloidal gold (Auc) NPs into electrospun polyethylene glycol (PEG) fibers to utilize the nanoparticle plasmonic response for localized heating and melting of the polymer to release medical treatment. Auc and Auc in PEG (PEG+Auc) both exhibited a minimum reflectivity at 522 nm or approximately green wavelengths of light under ultraviolet-visible (UV-Vis) spectroscopy. PEG+Auc ES fibers revealed a blue shift in minimum reflectivity at 504 nm. UV-Vis spectra were used to calculate the theoretical efficiency enhancement of PEG+Auc versus PEG alone, finding an approximate increase of 10 % under broad spectrum white light interrogation, and ∼14 % when illuminated with green light. Auc enhanced polymers were ES directly onto resistance temperature detectors and interrogated with green laser light so that temperature change could be recorded. Results showed a maximum increase of 8.9 °C. To further understand how gold nanomaterials effect the complex optical properties of our materials, spectroscopic ellipsometry was used. Using spectroscopic ellipsometry and modeling with CompleteEASE® software, the complex optical constants of our materials were determined. The complex optical constant n (index of refraction) provided us with optical density properties related to light wavelength divided by velocity, and k (extinction coefficient) was used to show the absorptive properties of the materials.

Metal–insulator–metal (MIM) resonant absorbers comprise a conducting ground plane, a dielectric of thickness t, and thin separated metal top-surface structures of dimension l. The fundamental resonance wavelength is predicted by an analytic standing-wave model based on t, l, and the dielectric refractive index spectrum. For the dielectrics SiO2, AlN, and TiO2, values for l of a few microns give fundamental resonances in the 8-12 μm long-wave infrared (LWIR) wavelength region. Agreement with theory is better for t/l exceeding 0.1. Harmonics at shorter wavelengths were already known, but we show that there are additional resonances in the far-infrared 20 - 50 μm wavelength range in MIM structures designed to have LWIR fundamental resonances. These new resonances are consistent with the model if far-IR dispersion features in the index spectrum are considered. LWIR fundamental absorptions are experimentally shown to be optimized for a ratio t/l of 0.1 to 0.3 for SiO2- and AlN-based MIM absorbers, respectively, with TiO2-based MIM optimized at an intermediate ratio.

In this paper, a colloidal solution of copper nanoparticles was prepared from a Cu ion aqueous solution with the protein casein surfactant by a liquid phase reduction method at low temperature below 373K. For the casein concentration ranging from 6g/L to 75g/L, the formation of copper nanoparticle colloid were observed. As a result, the peak was observed at the ranging of 450 to 650 nm corresponding to the copper nanoparticle colloid plasmon absorption. As the surfactant concentration increases, the absorption spectrum tends to blue-shift and the particle diameter decreases. Thus, it indicated that the optical property and particle diameter of copper nanoparticle colloidal solution will be controlled by the protein casein surfactant concentration.

Layered zirconium hydrogen phosphate intercalation compounds can be easily tuned, leading to potential applications in many fields, specifically by introducing them in different polymeric composites as nanofillers. Employing first-principles density functional theory based calculations, we have investigated ground state electronic structure properties of α-zirconium hydrogen phosphate (α-ZrP). We discuss the structure and electronic band structure, where projected density of states calculations have been discussed to understand the different atomic orbitals contributions to electronic bands. ZrP has numerous properties of interest for use in many semiconductor device structures, specifically, layered zirconium hydrogen phosphate has substantial promise for both optical devices and for high power electronics due to its large direct band gap. Our structural calculations suggest that layered zirconium hydrogen phosphate exhibits monoclinic structure. The calculated structural parameters and band gap are in good agreement with available experimental data.

Monolayer molecular electrodes composed of titanium oxide nanosheets (TiO2ns) or ruthenium oxide nanosheets (RuO2ns) were prepared and their activities in the oxygen reduction reaction (ORR) were evaluated to investigate the ORR active sites in oxide catalysts. In TiO2ns, the influence of physical distortion sites in the crystal structure formed by introducing oxygen vacancies was determined. The ORR activity of TiO2ns was improved by introducing physical distortion sites. In RuO2ns, the effects of both the type of crystal structure and electrochemical distortion sites arising from redox reactions on ORR performance were studied. The type of crystal structure had almost no effect on ORR activity. In contrast, electrochemical distortion sites were expected to behave as the ORR active sites because the on-set potential of the ORR was similar to the redox peak position for the RuO2ns. Thus, the distortion sites in oxide crystal structures may behave as the active sites in the ORR independent of the metal species.

Heat is the most ubiquitous form of energy on planet Earth. Every day, the sun continuously strikes the Earth’s surface with 120,000 Terawatts of energy. This solar energy is more than 10,000 times the amount of energy produced worldwide. With the scarcity of fossil fuels looming on the horizon and its adverse effect on the environment many researchers, from academia to industry, are exploring cleaner, greener and more efficient renewable energy technologies. Thermoelectricity can provide an alternative to hazardous fossil fuels as its electricity is produced directly from heat with no moving parts or working fluid. The efficiency of any thermoelectric material is given by a quantity called the figure of merit ZT. For thermoelectric (TE) devices to be competitive with fluid-based and other energy related devices, ZT greater than 2 is usually sought. Here, we report on the fabrication of thin film thermoelectric materials based on Bi2Te3/WS2 superlattice layer structure using RF magnetron sputtering deposition method. Quantum confinement in these low dimensional and ultrathin superlattices can enhance the density of states near the fermi level resulting in higher ZT value. The thermoelectric figure of merit can be enhanced by controlling the layer thickness close to the phonons mean free path. This way heat carrying phonons with different wavelengths can be scattered efficiently resulting in lower lattice thermal conductivity.

The present study investigated the adsorption of fluorides in natural zeolites clinoptilolite-type, sourced in Sonora, Mexico, and modified with Fe. Characterization of the material was carried out along with determination of kinetic parameters varying time and concentration of reagents to calculate maximum adsorption capacity. To determine thermodynamic parameters temperature was varied for accurate characterization of the adsorption process. It was found that the zeolite fixed Fe in its structure without model significant modification, likewise when put in contact with a fluoride solution (F-), it was capable of taking up these ions through adsorption due to the interaction between the sorbato and the pollutant. The kinetics best fit Pseudo-second-order model with Qmax=0.91 mgg-1, therefore it indicates that the process is reversible, spontaneous and endothermic what can favor the reuse of the material.

Aqueous rechargeable batteries are attractive owing to their higher operational safety, high ionic conductivity, scalable and easy manufacturing. These aqueous batteries form an economic option for large-scale (grid) power storage. In the aqueous battery sector, Mn-based compounds are highly attractive with their non-toxic nature, low-cost, rich mineral chemistry and robust operational safety. Several Mn-based systems like LiMn2O4 spinel and LiNi1/3Mn1/3Co1/3O2 have seen successful commercialization. Pursuing Mn-based materials, we have shown layer structured Na2Mn3O7 as a versatile cathode material for non-aqueous systems like Li-, Na- and K-ion batteries. In the current work, we have exploited Na2Mn3O7 as a cathode material for aqueous Zn-ion battery for the first time. This Na-Mn-O ternary system was prepared using two-step emulsion-based synthesis. The phase-pure Na2Mn3O7 was formed in a triclinic structure with a space group of P-1. It exhibited versatile electrochemical insertion of different ions like Li-, Na- and K-ions involving phase transition. Na2Mn3O7 exhibited reversible Zn-ion intercalation delivering capacity of 245 mA h g-1 with a nominal voltage of 1.5 V. Upon discharge, it triggered phase transformation to an unknown phase. Layered Na2Mn3O7 oxide was found to act as an efficient cathode for Zn-ion batteries with good cycling stability.

As the global energy and environmental preservation needs continue to grow, the demand for renewable and clean energy conversion materials and devices continues to rise as well. Thermoelectric (TE) materials and devices can convert waste heat into electricity and therefore it can be a potential renewable and clean energy source. Organic and polymeric materials typically exhibit low electrical conductivities, high Seebeck coefficients, and orders of magnitude lower thermal conductivities as compared to their inorganic counterparts. However, the electrical conductivities of organic/polymeric materials are tunable via doping or molecular engineering. In this study, a series of carefully doped P3HT composites are systematically evaluated for heat as well as light modulated devices. Along with a high absorption coefficient, when the polymer film thickness is less than the penetration depth of the incoming photons, the photo effects are significant and could be very useful for light modulations of thermoelectric functions. With further systematic studies and a better understanding of the mechanisms behind the photo-Seebeck effect, the development of potential high-efficiency multi-function materials and devices appears feasible.

The work presents an electrochemical study of the corrosion behaviour of two TiC/Cu-Ni metal matrix composites with a content of 10 and 20 wt.% Ni immersed in synthetic seawater. The composites were synthesized by a capillary infiltration technique, obtaining dense materials TiC/Cu-10Ni and TiC/Cu-20 Ni with a residual porosity of 1.8 and 1.7%, respectively. The corrosion rate (CR) was evaluated from the techniques of polarization curves (PC), linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). Electrochemical measurements were carried out under static conditions, ambient temperature and atmospheric pressure at 24 hours exposure in the electrolytic medium. The corrosion rate is affected by the Ni content in the matrix, with less corrosion in the composite with a higher Ni content. The higher content of Ni in the Cu-Ni alloy provides higher passivation and stability to the corrosion products film that are absorbed on the composite surface. Microscopic examination (SEM) showed a characteristic morphology of a corrosion mechanism of the localized type (pits and crevices) generated by a differential aeration, where the TiC/Cu-10Ni composite showed greater degradation.

Technological advances in synthesis and preparation of aerogels have resulted in formulations that have the mechanical integrity (while retaining flexibility) to be utilized in a broad range of applications and have overcome the initial brittleness that this class of materials was once known for. Both structural and functional aerogels show a drop in performance when subjected to certain cyclic thermal or impact loading due to the wear and formation of cracks, which reduces their lifespan. Here we present the proof-of-concept of a computational toolset that connects the change in thermal profile to structural failure and degradation. In combination with an appropriate finite element (FEM) solver, we have developed a genetic algorithm that can reconstruct the size and shape of the defective region in silica aerogels given the temperatures from a sensor grid. Results show that a heatmap can be used as the foundation for reconstructing faults and defects in thermally insulating materials. Furthermore, the model developed in this study can be expanded to accommodate other material types. Experimental setup can used to benchmark and refine the computational toolset.

We examined the influence of the microwave power on the diagonal resistance in the GaAs/AlGaAs two dimensional electron system (2DES), in order to extract the electron temperature and determine microwave induced heating as a function of the microwave power. The study shows that microwaves produce a small discernable increase in the electron temperature both at null magnetic field and at finite magnetic fields in the GaAs/AlGaAs 2DES. The heating effect at null field appears greater in comparison to the examined finite field interval, although the increase in the electron temperature in the zero-field limit appears smaller than theoretical predictions.

The voltammetric hysteresis visible in current density versus solar cell potential (J-V) curves is a serious concern because it is known that the performance of Dye-sensitized Solar Cells (DSCs) depends on the direction of the potential and the rate of scan. J-V characteristics of gel electrolyte based DSCs were obtained by varying the scan rate from 0.01 to 0.1 V s-1 and the direction from forward bias to reverse bias and reverse bias to forward bias. Three electrolytes were tested, two of them were 100% single salt electrolytes of KI and Hex4NI, and the other was a mixed salt electrolyte containing KI (75%) and Hex4NI (25%). DSC containing mixed salts electrolyte exhibited higher efficiency than single salt electrolytes. The energy conversion efficiency with mixed salts increased from 5.9 to 6.4% with the increase of the scan rate from 0.01 to 0.1 V s-1, when the scanning was conducted from forward bias to reverse bias direction. However, when the scanning was carried out with revised polarity a drop of the efficiency was observed with increasing rate of potential scan. Present work emphasizes the importance of reporting the rate and direction of potential scan along with solar cell performance parameters.

Dimethylformamide (DMF) has been tested as corrosion inhibitor in a metallic material like API 5LX70 in a corrosive solution of 3% of NaCl and using electrochemical technique as electrochemical impedance spectroscopy. The results showed that 20 ppm is the best concentration to protect the metallic surface of API 5L X70 with η∼ 94%. Hydrodynamic conditions (100 and 1000 rpm) demonstrated that the DMF at different concentration afforded moderate protection against corrosion with inhibition efficiency ∼70%. Finally, the adsorption of this compound follows the Langmuir isotherm with a chemisorption-physisorption process.

The wafering of thin silicon substrates is done by wire sawing technology. In this work a numerical model for the investigation of microstructural mechanisms like cracking and damage evolution during the sawing process is presented. A three-dimensional finite element model representing the phase transformation properties of silicon is validated by loading curves from nano-indentation experiments. By using cohesive zone finite elements, the crack lengths as well as crack initiation depths can be quantified and compared with the experimental results in terms of the maximum depth of subsurface damage.

Currently, the main material for the production of solar cells is still silicon. More than 70% of the global production of solar cells are silicon based. For solar-grade silicon production the technologies based on the reduction of silicon from organosilicon compounds are mainly used. These technologies are energy-consuming, highly explosive and unsustainable.

The present paper studies the technology of purification of metallurgical-grade silicon by vacuum-thermal and plasma-chemical treatment of silicon melt under electromagnetic stirring using numerical simulation and compares this technology with the existing ones (silane technologies and Elkem Solar silicon (ESS) production process) in terms of energy consumption, environmental safety and the process scalability.

It is shown that the proposed technology is environmentally safe, scalable and has low power consumption. The final product of this technology is multicrystalline silicon, ready for silicon wafer production.

Hexagonal boron nitride (hBN), a two dimensional (2D) material, has emerged as an important substrate and dielectric for electronic, optoelectronic, and photonic devices based on graphene and other atomically thin two dimensional materials. Here we report on the initial oxidation of (0001) hBN single crystals in ambient air as functions of temperature and time, as determined by atomic force microscopy (AFM) and scanning electron microscope with energy dispersive X-ray spectroscopy (SEM/EDS). For oxidation times of 20 minutes, the first evidence of oxidation appears at 900°C, with the formation of shallow, hexagonal-, and irregular-shaped pits that are less than 100 nm across and several nanometer deep. Oxidation at 1100°C for 20 minutes produced 1.0-2.0-micron size pits with flat and pointed bottoms that were approximately hexagonal-shaped, but with rough and irregular edges, and multiple interior steps. Oxidation was not uniform on the surface of hBN, but starts where dislocations in the crystal intersected the surfaces. Pit depth increased linearly with temperature and oxidation times. In addition to the surface pits, small particles formed on the surface. Elemental analysis of the thermally oxidized hBN crystals by SEM/EDS revealed the major elements of these particles were boron and oxygen.

Oriented ZnO seed layers were deposited by three different techniques, namely, simple drop casting (DC), sol-gel derived dip coating (DPC) and spin coating of ball-milled ZnO powder solution(BMD) for the subsequent growth of vertically aligned ZnO nanorods along the substrate normal. X-ray diffraction (XRD) analyses revealed that ZnO(DC) seed layer exhibit the highest preferential c-axis texturing among the ZnO seed layers synthesized by different techniques. The Scanning Electron Microscopy (SEM) analysis evident that the morphology of ZnO seed layer surface is compact and coherently carpets the underlying substrate. ZnO nanorods(NRs) were then grown by hydrothermal method atop the ZnO seeded and non-seeded substrates grown by different techniques to elucidate the best ZnO seed layer promoting well-aligned ZnO Nanorods. The presence of c-axis oriented ZnO(DC) seeding layers was found to significantly affect the surface morphology and crystallographic orientation of the resultant ZnO NRs films. The optical band gap of ZnO(DC) seed and ZnO NRs were estimated to be 3.30 eV and in the range of 3.18 – 3.25 eV respectively by using UV-VIS-NIR diffuse reflection spectroscopy. The room temperature photoluminescence analyses revealed that nanostructured ZnO films exhibit a sharp near-band-edge luminescence peak at ∼380 nm consistent with the estimated optical band gap and the ZnO nanorod arrays are notably free from defect-related green-yellow emission peaks.

Microsupercapacitors (MSCs) are miniaturized energy storage devices that can be integrated in an on-chip platform as a component of a power supply for Internet of things’ sensors. Integration of these on-chip MSCs require them to be fabricated through CMOS compatible fabrication techniques such as spin coating. One of the biggest challenges in spin coated MSCs is the poor surface adhesion. In this work, we present a CMOS compatible electrode deposition process with enhanced adhesion and retention for reduced graphene oxide (rGO) using spin coating. In order to improve the adhesion and surface uniformity of the deposited electrode material, the surface of Si/SiO2 wafers was subjected to roughening through Fe nanoparticle formation. A 4 nm thick Fe layer deposition substantially magnified the average mean surface roughness of the substrates. In comparison with substrates without the Fe deposition, the treated ones have more than 300% improvement in surface coverage and rGO mass retention after sonication testing. These results suggest that the surface roughening has a positive influence on electrode deposition via a spin-coating method.

In the context of safety assessment, the fraction of inventory that is expected to rapidly dissolve when water contacts the spent fuel is called the Instant Release Fraction (IRF). Conceptually, this fraction consists of radionuclides outside of the uranium dioxide matrix and therefore the fraction can be further divided into the radionuclides in the fuel/cladding gap and radionuclides in the grain boundaries. The relative importance of these two fractions is investigated here for two Swedish high burnup fuels through simultaneous grinding and leaching fuel fragments in simplified groundwater for a short period of time. The hypothesis is that this will expose grain boundaries to leaching solution and provide an estimate of the release of the grain boundary inventory upon contact with water. The studied fragments were used in previous leaching experiments and thus pre-washed to remove any pre-oxidized phases. The results showed a significant release of iodine, cesium and rubidium and to a lower extent molybdenum and technetium. The fraction of inventory in the aqueous phase of actinides and lanthanides was 1-2 orders of magnitude lower than for the elements associated to the IRF. Both fuels displayed a very similar behavior and no correlation as a function of burnup or fission gas release was found.