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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Enhancement of electrical parameters in solar grade monocrystalline silicon by external gettering through sacrificial silicon nanowire layer

Highlights: • Silicon nanowire-based gettering process decreases the metallic impurity concentration. • Gettering process ameliorates the transport parameters of silicon substrates. • The electrical properties of silicon solar cells are significantly improved. - Abstract: In this work, we report a simple and efficient purification technique of solar grade silicon wafers suitable for high efficiency and low-cost silicon solar cells. This gettering method requires the elaboration of silicon nanowire thin layer followed by an annealing treatment and removing impurity loaded silicon nanowires. ICP-AES analysis shows a significant decrease in the metallic impurity concentration resulting considerable enhancement in the silicon purity grade. Electrical characterizations reveal a global decrease of the majority carrier concentration and a substantial improvement of the minority carrier lifetime. Furthermore, the application of this novel gettering process induces an enhancement in the silicon solar cell electrical parameters. These results give evidence of the effectiveness of the proposed purification method to produce efficient solar cells starting from low-quality silicon wafers.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

A Mg2+-Ge4+ substituting strategy for optimizing color rendering index and luminescence of YAG: Ce3+ phosphors for white LEDs

Highlights: • Mg{sup 2+}-Ge{sup 4+} ion pairs can partially substitute the Al{sup 3+} ions of YAG successfully. With the substitution, the garnet crystal structure remains unchanged. • With increasing Mg{sup 2+}-Ge{sup 4+} ions concentrations, the emission spectra show a progressive red-shift, from 528 to 552 nm (about 24 nm). • In white LEDs, with increasing Mg{sup 2+}-Ge{sup 4+} ions concentrations, the CCT decreased gradually from 6798 to 3261 K and the CRI increased from 76.5 to 89.3. - Abstract: Mg{sup 2+}-Ge{sup 4+} ions substituted YAG: Ce{sup 3+} phosphors (Y{sub 3}Al{sub 5-2x}Mg{sub x}Ge{sub x}O{sub 12}: Ce{sup 3+}) were prepared by high temperature solid state reaction method. X-ray diffraction (XRD), Scanning election microscope (SEM), Photoluminescence (PL) spectra and so on were used to characterize the samples. The effects of Mg{sup 2+}-Ge{sup 4+} concentrations on the morphology, structure, luminescence properties, fluorescence lifetime and white LED performance of YAG: Ce{sup 3+} phosphors were studied in detail. The results indicate that Mg{sup 2+}-Ge{sup 4+} ion pairs can partially substitute the Al{sup 3+} ions of YAG successfully. With the substitution, the garnet crystal structure remains unchanged. However the emission spectra show a progressive red-shift, from 528 to 552 nm (about 24 nm). The lifetime decreased rapidly from 84 to 26 ns. In particular, the correlated color temperature (CCT) decreases gradually from 6798 to 3261 K and the color rendering index (CRI) increases from 76.5 to 89.3 with the increasing of the incorporation content of Mg{sup 2+}-Ge{sup 4+} ion pairs.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Effect of Cu dopant on the structural, magnetic and electrical properties of Ni-Zn ferrites

Highlights: • Ni{sub 0.8-x}Cu{sub x}Zn{sub 0.2}Fe{sub 2}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6) Spinel ferrites synthesized through auto-combustion method and their structural and magnetic properties investigated by XRD, SEM, FTIR and VSM measurements. • Increase in crystal and particle size and decrease in saturation magnetization resulted from substitution on Ni by Cu. • Observed values of (ε) and (tanδ) of the samples show the deterministic role of density in electrical properties of spinel ferrites. - Abstract: Ni{sub 0.8-x}Cu{sub x}Zn{sub 0.2}Fe{sub 2}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6) ferrite was synthesized through auto-combustion method. (XRD) patterns confirmed the crystallization of the samples in spinel structure. FESEM showed that the size of ferrite particles are about few hundred nanometers and with increase in Cu concentration (x) in the structure there is increase in particle size. Fourier transform infrared (FTIR) spectrometry indicates that octahedral and tetrahedral sites are formed. Vibrating sample magnetometer (VSM) results proved reduction of saturation magnetization (M{sub s}) by increasing Cu content, which is explained according to the ferrimagnetic nature of these samples in which Ni is replaced by Cu at octahedral site. Real part of dielectric constant (ε) and loss tangent (tanδ) of samples were also studied in frequency range of 100–20000 Hz. Results showed an increase in ε and tanδ of the sample with x = 0.6 which is considered to be the result of higher density of this sample.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Screen printing large-area organometal halide perovskite thin films for efficient photodetectors

Highlights: • A stable paste with perovskite precursor was produced out. • Screen printing was proposed to fabricate perovskite thin films. • The perovskite photodetectors with symmetric architectures show reasonable performance with high photocurrent and fast response. - Abstract: Organometal halide perovskites have demonstrated excellent features compared to conventional optoelectronic materials. To date, the perovskite films have generally been fabricated by either spin coating or vapor deposition. However, both methods cannot simultaneously meet large scale and low cost of production. Here, a simple, low-cost and high-throughput strategy was proposed to fabricate perovskite thin films, which were further applied in photodetectors. First, lead compound nanoparticles were synthesized by a solvent precipitation method, then a paste with the lead compound nanoparticles was screen printed to form PbO films involving calcination, and next the PbO films directly reacted with CH{sub 3}NH{sub 3}I solution to convert into CH{sub 3}NH{sub 3}PbI{sub 3} films. The CH{sub 3}NH{sub 3}PbI{sub 3} films consisted of micron crystals, whose sizes can be effectively controlled by adjusting CH{sub 3}NH{sub 3}I concentration. Furthermore, the CH{sub 3}NH{sub 3}PbI{sub 3} films were applied in photodetectors, which showed good performance with high sensitivity and fast response.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Realization of strong violet and blue emissions from ZnO thin films by incorporation of Cu ions

Highlights: • A strong blue-violet co-emission occurs after Cu ions are doped into ZnO thin films.. • The violet emission centered at 430 nm is attributed to transitions of electrons from conduction band to Cu{sup +} acceptor levels. • The blue emission centered at 470 nm is attributed to transitions of electrons from Cu{sup 2+} donor levels to Cu{sup +} acceptor levels. • Both the violet and blue emissions decrease when Cu-doping concentration is higher than 2 at.%. - Abstract: In recent years, Cu-doped ZnO materials have attracted wide attention due to some unique properties, such as p-type conduction, room-temperature ferromagnetism and plentiful luminescence behavior. In this work, Cu-doped ZnO thin films with different doping levels were prepared by sol–gel method. The structural, morphological features and the composition of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX), respectively. The optical properties were analyzed by the UV–visible transmittance spectra and fluorescence spectra. The Cu-doping in a low concentration does not influence the crystal phase of wurtzite ZnO and has a very small impact on c-axis preferred orientation of ZnO thin films. With the increase of Cu-doping concentration, the Cu ions are gradually changed from dominant Cu{sup +} ions to dominant Cu{sup 2+} ions. Cu-doping in a low concentration caused strong blue-violet emissions in ZnO thin films. The violet emission is attributed to the transition of electrons from the conduction band to Cu{sup +} acceptor levels, and the blue emission is ascribed to the transition of electrons from Cu{sup 2+} donor levels to Cu{sup +} acceptor levels.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Effect of Ag3Sn nanoparticles and temperature on Cu6Sn5 IMC growth in Sn-xAg/Cu solder joints

Highlights: • The number density of Ag{sub 3}Sn grains precipitated upon Cu{sub 6}Sn{sub 5}, increases with Ag content and reflow temperature (T). • Raising of wt. % of Ag in solder and lowering of T can cause an increase in grain diameter of Ag{sub 3}Sn nanoparticles. • The blockading effect of Ag{sub 3}Sn particles on Cu{sub 6}Sn{sub 5} IMC growth is more pronounced in Sn-3Ag and Sn-3.5Ag alloys. • IMC suppressing nanoparticles can be utilized for solder materials design. - Abstract: The growing importance of Pb-free Sn-xAg solders and high cost of Ag has attracted the attention of researchers to perform experiment with solders with varied content of Ag element. In this study, Sn-xAg(0,1,2,3.5) solder balls on Cu substrate have been reflowed at 250/275/300 °C for 60 s and air cooled. Finite element method has been utilized to simulate the concentration and temperature during cooling. The experimental results suggest that the Cu flux through grain boundary diffusion is the dominant mechanism for Cu{sub 6}Sn{sub 5} intermetallic compound growth in Pure Sn and Sn-1Ag solders. When the Ag content is increased, as in case of Sn-3Ag and Sn-3.5Ag alloys; the shielding effect of Ag{sub 3}Sn nanoparticles is the determinant factor for affecting the thickness of Cu{sub 6}Sn{sub 5} IMC. Both Cu influx rate and shielding effect of Ag{sub 3}Sn nanoparticles are enhanced with the raise in pre-cooled isothermal reflow temperature. Sn-1Ag solder is observed to have the thickest Cu{sub 6}Sn{sub 5} IMC.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Control of donor-like effect in V2VI3 polycrystalline thermoelectric materials

Highlights: • Thermal control of donor-like effect for V{sub 2}VI{sub 3} polycrystalline materials is proposed. • Low-temperature sintering or hot deforming facilitates the donor-like effect. • Recovery role by high-temperature sintering/deforming enhances the Seebeck coefficient. • Temperature should be strictly selected for each V{sub 2}VI{sub 3} polycrystalline material. - Abstract: Intrinsic point defect plays a core role in improving thermoelectric performance of V{sub 2}VI{sub 3} polycrystalline materials. However, the control of intrinsic point defect is challenging during powder refinement due to the donor-like effect. This paper shows a systematic approach to thermal control the donor-like effect via engineering spark plasma sintering and hot deformation temperature. Bi{sub 2}Te{sub 2.85}Se{sub 0.15} polycrystalline alloy with high electron concentration was chosen as example to validate the method. The low Seebeck coefficient of n-type Bi{sub 2}Te{sub 2.85}Se{sub 0.15} polycrystalline, arising from strong donor-like effect after powder refinement, was enhanced by recovery role induced reduction in electron concentration through proper tuning sintering or deforming temperature. Repetitive hot deformation was applied to further improve the Seebeck coefficient via the recovery role and a maximum zT of 1.0 is obtained at 410 K. The present results give insights into developing higher performance V{sub 2}VI{sub 3} polycrystalline materials through thermal control the donor-like effect.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Gas sensor based on three dimensional Bi2S3 nanowires network for ammonia detection at room temperature

Highlights: • Three dimensional Bi{sub 2}S{sub 3} nanowires networks. • High response to NH{sub 3} gas. • Good selectivity. • Wide linear range. • Work at room temperature. - Abstract: A film containing three dimensional Bi{sub 2}S{sub 3} nanowires network was obtained using Bi(NO{sub 3}){sub 3} and thioacetamide as starting materials through three steps, namely the chemical synthesis of Bi{sub 2}S{sub 3}, preparation of its sol under ultrasonic condition and crystal self-assembly at 25 °C. The nanowires had diameters of 20–100 nm. The formation mechanism of the 3D nanowires network is the anisotropic growth of Bi{sub 2}S{sub 3}. The sensor based on 3D Bi{sub 2}S{sub 3} nanowires network with an excellent response to ammonia at 30 °C. The response mechanism of the sensor for ammonia is a weak coordination adsorption of ammonia molecule on the Bi{sub 2}S{sub 3} nanowires and the electron is partially transferred from ammonia molecule to bismuth (III) ion. The maximum response of the sensor to ammonia was up to 82.3 and had a good linear range from 30 to 350 ppm concentration, indicating its potential applications in the determination and leak alarm of ammonia.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Hydrothermal synthesis of molybdenum trioxide, characterization and photocatalytic activity

Highlights: • α-MoO{sub 3} micro-belts were synthesized hydrothermally. • Micro-belts were found very rich in surface oxygen vacancies. • CR-F3BS photocatalytic degradation was promising. • The cytotoxicity and mutagenicity were reduced significantly of CR-F3BS. - Abstract: α-MoO{sub 3} micro-belts were synthesized via hydrothermal technique and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDX) and particle size analyzer. Photo-catalytic activity was evaluated by degrading Coralene Red F3BS (CR-F3BS) dye and process variables i.e., pH, photocatalyst dose, concentration of CR-F3BS and UV exposure time were optimized using response surface methodology (RSM) under central composite design (CCD). Under optimized conditions, up to 95% degradation of CR-F3BS (10 mg/L) was achieved for 120 min UV irradiation time at pH 7 using 2.75 g/L catalyst dose. The obtained RSM model revealed a satisfactory correlation between experimental and predicted CR-F3BS degradation values. Ames and heamolytic tests revealed that the toxicity was reduced significantly as a result of photo-catalytic treatment. In view of promising efficiency, α-MoO{sub 3} micro-belts could possibly be used for the degradation of dyes in textile effluents.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of reaction time on the dielectric behaviour of reduced graphene oxide–layered cobalt hydroxide composite for high-k gate dielectrics

Highlights: • Disc-like layered cobalt hydroxide microparticles were synthesized on reduced graphene oxide using one-pot hydrothermal method. • An enhanced dielectric constant of 7.19 × 10{sup 6} with a capacitance of 2.44 × 10{sup −6} F was achieved at 100 Hz frequency. • A leakage current of a few mA was produced in the composites that find potential applications in high-k gate dielectrics. - Abstract: Reduced graphene oxide (RGO)–cobalt hydroxide [Co(OH){sub 2}] composite was synthesized using one-pot hydrothermal method. The frequency-dependent dielectric properties and leakage conduction mechanism were studied for the composite. Samples were made with different reaction times of 2, 4, 6 and 12 h for the same concentration of graphene oxide and cobalt nitrate at constant temperature and pH. A high dielectric constant of 7.19 × 10{sup 6} with a capacitance of 2.45 × 10{sup −6} F was achieved for a reaction time of 2 h, at 100 Hz frequency and 27 °C temperature. One order decrement in the dielectric constant (10{sup 5}) was found with an increase in time starting from 4 to 12 h. The leakage current characteristics revealed Schottky barrier-type conduction mechanism in the composites. Thus, RGO-Co(OH){sub 2} composite with a high dielectric constant, microcapacitance and large leakage current could be regarded as a potential high-k candidate, which has its application as a gate dielectric material in the fabrication of metal oxide semiconductor field effect transistor.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Stable dielectric, elastic, and piezoelectric properties of Yb3+:CNGS crystals at high temperature

Highlights: • Single crystals Yb:CNGS with high quality have been successfully grown using the Czochralski method. • The dielectric, elastic and piezoelectric coefficients are measured and calculated according to the impedance method. • Piezoelectricity and dielectric properties at room temperature and elevated temperature are investigated for the first time. • The doped crystals show good temperature stability at elevated temperature condition. - Abstract: In this study, Yb{sup 3+}:Ca{sub 3}NbGa{sub 3}Si{sub 2}O{sub 14} (Yb{sup 3+}:CNGS) single crystals with different doping concentrations (2 and 5 at%) were grown using the Czochralski method. The dielectric, elastic, and piezoelectric coefficients at room temperature and elevated temperature were measured and calculated according to the impedance method for the first time. Crystals show excellent piezoelectricity and exhibit favorable temperature stability from room temperature to 800 °C. The transmittance spectrum of the Yb{sup 3+}:CNGS crystals is also recorded, and the results prove the high optical quality of these crystals.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Luminescence properties of Eu2+-activated NaCaBeSi2O6F for white light-emitting diode applications

Highlights: • A novel blue-emitting garnet NaCaBeSi{sub 2}O{sub 6}F:Eu{sup 2+} phosphor was synthesized. • The broad NUV excitation band (300–400 nm) gives blue emission. • The LED made with NaCaBeSi{sub 2}O{sub 6}F:Eu{sup 2+} and green and red-emitting phosphors gives white-light emission. - Abstract: A series of blue-emitting NaCaBeSi{sub 2}O{sub 6}F:Eu{sup 2+} phosphors were obtained via a solid state reaction. NaCaBeSi{sub 2}O{sub 6}F:Eu{sup 2+} exhibit a broad absorption from 250 to 450 nm when monitored at 467 nm and display a broad emission band from 400 to 600 nm when excited at 397 nm. The concentration quenching was obtained when the concentration of Eu{sup 2+} was increased to 0.8 mol%. Energy transfer interactions between Eu{sup 2+} in host is due to dipole-dipole mechanisms and the critical distance was calculated to be 31.96 Å. The results obtained in this study highly indicates that NaCaBeSi{sub 2}O{sub 6}F:Eu{sup 2+} can be a potential blue-emitting phosphor for light quality improvement in white-LED applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Energy transfer and tunable emission of Ca14Al10Zn6O35:Bi3+,Sm3+ phosphor

Highlights: • We have firstly synthesized a single-phased Ca{sub 14}Al{sub 10}Zn{sub 6}O{sub 35}:Bi{sup 3+},Sm{sup 3+} phosphor. • Different measurement support the energy transfer from Bi{sup 3+} to Sm{sup 3+}. • Based on the energy transfer, tunable emission were realized. - Abstract: A series of Bi{sup 3+}, Sm{sup 3+}-codoped Ca{sub 14}Al{sub 10}Zn{sub 6}O{sub 35} phosphors were synthesized via conventional high temperature solid-state method. The crystal structure, morphology, photoluminescence and energy transfer mechanism from Bi{sup 3+} to Sm{sup 3+} were investigated in detail. A broad blue emission band due to {sup 3}P{sub 1} → {sup 1}S{sub 0} transition of Bi{sup 3+} was observed in the Bi{sup 3+} single-doped Ca{sub 14}Al{sub 10}Zn{sub 6}O{sub 35} sample, the Ca{sup 2+} position are verified to be replaced by Bi{sup 3+} and the corresponding concentration quenching mechanism was dipole-dipole interaction. The considerable spectral overlap between the broad emission band of Bi{sup 3+} around 350–550 nm and the excitation band of Sm{sup 3+} supports the energy transfer from Bi{sup 3+} to Sm{sup 3+}. This investigation will contribute to the comprehension of interactions between Bi{sup 3+} and Sm{sup 3+}. These results reveal the potential application of Bi{sup 3+}, Sm{sup 3+} co-doped phosphor in UV light-emitting diodes and artificial light in plant.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Efficiently enhanced photoluminescence in Eu3+-doped Lu2(MoO4)3 by Gd3+ substituting

Highlights: • The Gd{sup 3+} doped samples had been discovered to show much better luminescent properties than Lu{sub 2}(MoO{sub 4}){sub 3}:0.02Eu{sup 3+}. • The influence of Gd{sup 3+} ions on luminescence behavior was discussed. • The DFT calculation indicates that the structure of Gd{sub 2}(MoO{sub 4}){sub 3} is more propitious for luminescence than that of Lu{sub 2}(MoO{sub 4}){sub 3}. - Abstract: A series of Lu{sub 2-x}Gd{sub x}(MoO{sub 4}){sub 3}:0.02Eu{sup 3+} (x = 0–2) red-emitting phosphors have been synthesized by the standard solid-state reaction method. Interestingly, the Gd concentration plays a profound role to influence the luminescence property. A conspicuous monotonic increase could be found in the influence of Gd{sup 3+} concentration to the emission intensity, and finally Gd{sub 2}(MoO{sub 4}){sub 3}:0.02Eu{sup 3+} exhibits the strongest red light emission with the intensifying factor even reaching 3.04-fold compared to Lu{sub 2}(MoO{sub 4}){sub 3}:0.02Eu{sup 3+}. Careful structural analysis suggested that up to about 80% (x = 1.6) Lu can be substituted by Gd with the same crystal structure of Lu{sub 2}(MoO{sub 4}){sub 3} being retained, while a higher Gd concentration would lead to it crystallizing in the Gd{sub 2}(MoO{sub 4}){sub 3} structure. We believe that the variation of crystal structure is responsible for the photoluminescence enhancing process.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Conversion of broadband UV-visible to near infrared emission by LaMgAl11O19: Cr3+, Yb3+ phosphors

Highlights: • Energy transfers from Cr{sup 3+} single ions and Cr{sup 3+}-Cr{sup 3+} ion pairs to Yb{sup 3+} ions are both witnessed in LaMgAl{sub 11}O{sub 19}: Cr{sup 3+},Yb{sup 3+}. • Phonon-assisted energy transfer mechanism is verified based on doping concentration and temperature dependent luminescence behaviors. • The phosphor is possible to convert light in region of 250–650 nm into 980 nm light to enhance solar cell efficiency. - Abstract: The Cr{sup 3+}, Yb{sup 3+} co-doped LaMgAl{sub 11}O{sub 19} spectral conversion materials have been synthesized by solid-state reaction method. The phosphor can absorb photons in UV–vis spectral region and then give intense near-infrared emission around 980 nm originated from Yb{sup 3+}: {sup 2}F{sub 5/2} → {sup 2}F{sub 7/2} transition. Phonon-assisted energy transfers from Cr{sup 3+} ions and Cr{sup 3+}-Cr{sup 3+} ion pairs to Yb{sup 3+} ions are both witnessed in LaMgAl{sub 11}O{sub 19} host. The doping concentration and temperature dependent luminescence properties have been investigated. It is believed that Cr{sup 3+}, Yb{sup 3+} co-doped LaMgAl{sub 11}O{sub 19} phosphor might potentially act as spectral convertor for silicon-based solar cells to enhance the photovoltaic conversion efficiency.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Facile room temperature CTAB-assisted synthesis of mesoporous nano-cobalt ferrites for enhanced magnetic behaviour

Highlights: • Synthesis of mesoporous nano-cobalt ferrites are carried out CTAB medium. • Crystalline cobalt ferrite phase was formed below CMC of CTAB. • Bilayer arrangement of CTA-OH-Fe-Co growing units leads to inter-particle pores. • Enhanced magnetic properties (M{sub s} and H{sub c}) were obtained in synthesized cobalt ferrites. - Abstract: We report a facile, room temperature synthesis of nanostructured mesoporous cobalt ferrites using the cationic surfactant, cetyltrimethylammonium bromide (CTAB). The synthesis was carried out at various concentrations of CTAB ranging from its pre- to post-micellar concentrations. The pristine and calcined samples exhibit pure cobalt ferrite phase which are confirmed by XRD studies. The morphology of all uncalcined samples was quasi-spherical as shown by TEM images. Nitrogen adsorption – desorption study on pristine samples indicates the presence of mesopores in them. The magnetic properties of the uncalcined and calcined samples were studied by vibrating sample magnetometry. Coercivity and saturation magnetization were found to vary with the concentration of the CTAB employed. Also, the pristine samples were soft magnets, whereas the calcined samples tended towards exhibiting hard magnetism. We have proposed a mechanism to explain the mesoporosity of nanostructured ferrite based the role of CTAB in the present synthetic method.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Photosynthesis of silver nanoparticles using Durio zibethinus aqueous extract and its application in catalytic reduction of nitroaromatics, degradation of hazardous dyes and selective colorimetric sensing of mercury ions

Highlights: • Sunlight mediated synthesis of silver nanoparticles. • dAgNPs serves as an excellent catalyst to degrade organic dyes. • The degraded organic dyes are nontoxic. • dAgNPs colorimetrically detects mercury ions at micromolar concentration. - Abstract: A simple green route was reported to prepare highly stable silver nanoparticles. The aqueous leaf extract of Durio zibethinus reduces Ag+ to Ag0 in the presence of natural sunlight. The capping and stabilization of dAgNPs by the phytoconstituents of Durio zibethinus was confirmed by FTIR. TEM confirms that the dAgNPs are spherical in shape with a size range between 10–25 nm. XRD pattern confirmed that the dAgNPs are arranged in the face-centred cubic structure. The catalytic activity of the dAgNPs was proved by sodium borohydride mediated reduction of nitro aromatic compounds and degradation hazardous organic dyes. The reaction kinetics was analysed by pseudo-first order equation. Regardless of the efficacy of degrading organic dyes, we showed by zebrafish mortality assay that the toxicity of the dye degraded water reduced drastically. Besides catalysis, the dAgNPs has the potential to selective colorimetric sensing of hazardous mercury ion in aqueous solution.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

3D Photocatalytic media for decontamination of water from pesticides

Highlights: • Development of new photocatalytic media for decontamination of water from pollutants. • Deposition of TiO{sub 2} on alveolar macroporous media using the sol-gel method. • Use of aluminum foam as photocatalyst support. • A complete degradation of pyrimethanil was observed using the developed media. - Abstract: This work focuses on the development of innovative photocatalytic material, for decontamination of water from pollutants, by functionalization of reticulated metallic foam with TiO{sub 2}. The composition and texture of the prepared photocatalyst support were characterized using scanning electron microscope. The results showed a good deposition of the catalyst on the surface of the tested media with a recovery rate of 40 ± 3% which was interesting comparing to the coating rate obtained with industrial media (<20%). To prove the efficiency of the developed materiel, the photodegradation of pyrimethanil, at room temperature using the developed support under UV radiation was tested. A complete degradation of pyrimethanil was observed. The time required for total elimination of the pesticide varies depending on the initial concentration and in general, it was observed that a higher pesticide concentration required a longer time to be eliminated, however, for all tested concentrations, 5 h were sufficient for total elimination.

36 MATERIALS SCIENCE↗