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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Synthesis, Luminescence and Thermal Properties of PVA–ZnO–Al{sub 2}O{sub 3} Composite Films: Towards Fabrication of Sunlight-Induced Catalyst for Organic Dye Removal

Poly(vinyl alcohol) (PVA)–ZnO–Al{sub 2}O{sub 3} composite films have been prepared by the addition of different compositions of ZnO and Al{sub 2}O{sub 3} through solvent casting method. Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–Vis) and photoluminescence spectroscopy (PL) spectra revealed the successful incorporation of ZnO and Al{sub 2}O{sub 3} onto PVA and interactions among ZnO, Al{sub 2}O{sub 3} and PVA molecules. PL data indeed showed the enhanced luminescence property of composite films compared with the PVA. Thermogravimetric analysis (TGA) data showed that thermal stability of PVA–ZnO–Al{sub 2}O{sub 3} composite films could be greatly improved by the incorporation of ZnO and Al{sub 2}O{sub 3} into the system. The glass transition temperature (T{sub g}) were increased for the composite samples using ZnO and Al{sub 2}O{sub 3}. Differential scanning calorimetry (DSC) measurements revealed that the melting temperature (T{sub m}) of PVA–ZnO–Al{sub 2}O{sub 3 }composite films are significantly higher (~ 12 to 25 °C) than PVA. The photocatalytic measurements exhibited better photocatalytic degradation ability of PVA–ZnO–Al{sub 2}O{sub 3} composites over PVA. Such photocatalytic capacity makes the PVA–ZnO–Al{sub 2}O{sub 3} composite films promising candidates for the removal of organic dyes for water purification.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Generation of high-value products by photosynthetic microorganisms: From sunlight to biofuels

In this paper, oxygenic photosynthesis is the singular important chemical process providing the energy source for almost all life on earth. It harnesses and stores sun energy in forms of high-energy intermediates, such as low potential electrons and ATP, used as energy sources primarily for the fixation of carbon from atmosphere into carbohydrates. The latter compounds supply carbon and energy to multiple anabolic processes associated with cell growth and division.

09 BIOMASS FUELS↗
DOE OSTI2016

Synthesis of α-MoO{sub 3} nanoplates using organic aliphatic acids and investigation of sunlight enhanced photodegradation of organic dyes

Graphical abstract: Thermodynamically stable α-MoO{sub 3} nanoplates and nanorods were synthesized using organic structure controlling agents and demonstrated sun light enhanced photocatalytic degradation of methylene blue (MB) and rhodamine blue (Rh-B) dyes in aqueous solution. - Highlights: • α-MoO{sub 3} hexagonal nanoplates using organic structure controlling agents. • Tunable optical band gap of MoO{sub 3}. • Demonstrated strong sun light mediated enhanced photodegradation of methylene blue and rhodamine blue. • Photodegradation did not use any other external oxidizing agents. - Abstract: Thermodynamically stable α-MoO{sub 3} nanoplates were synthesized using organic aliphatic acids as structure controlling agents and investigated photocatalytic degradation of methylene blue (MB) and rhodamine blue (Rh-B) in presence of sun light. Three different organic aliphatic acids, citric acid (CA), tartaric acid (TA) and ethylene diamine tetra-acetic acid (EDTA), were employed to control morphologies. CA and TA predominantly produced extended hexagonal plates where EDTA gave nanorods as well as nanoplates. PXRD studies confirmed the formation of α-MoO{sub 3} nanoparticles. HR-TEM and FE-SEM reveal the formation of plate morphologies with 20–40 nm thickness, 50–100 nm diameter and 600 nm lengths. The different morphologies of α-MoO{sub 3} nanoparticles lead to the tunable optical band gap between 2.80 and 2.98 eV which was obtained from diffused reflectance spectra (DRS). Interestingly, the synthesized α-MoO{sub 3} nanoplates exhibited strong photocatalytic degradation of MB and Rh-B up to 99% in presence of sun light without using any oxidizing agents.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Fluorescent cooling of objects exposed to sunlight – The ruby example

Various pigments are used to formulate desirable non-white colors that stay cooler in the sun than alternatives, which is particularly useful for hot climate areas. These cool pigments provide a high near-infrared (NIR) reflectance in the solar infrared range of 700-2500 nm, and also a color specified by a reflectance spectrum in the 400-700 nm visible range. Still cooler materials can be formulated by also utilizing the phenomenon of fluorescence (photoluminescence). Ruby, Al 2 O 3 :Cr, is a prime example, with efficient emission in the deep red (~694 nm) and near infrared (700-800 nm). A layer of synthetic ruby crystals on a white surface having an attractive red color can remain cooler in the sun than conventional red materials. Ruby particles can also be used as a red/pink pigment. Increasing the Cr:Al ratio produces a stronger (darker) pigment but doping above ~3 wt% Cr 2 O 3 causes concentration quenching of the fluorescence. The system quantum efficiency for lightly doped ruby-pigmented coatings over white is high, 0.83 ± 0.10.

14 SOLAR ENERGY↗
DOE OSTI2023

Correction to “Ruthenium Dye Excitations and Relaxations in Natural Sunlight”

An error in computing the optical rate coefficients for dye RuP was discovered in Table S4 of the Supporting Information Section S8 Model S? for this article, published in J. Phys. Chem. A, 2021, 125, 4365-4372, 10.1021/acs.jpca.1c02386. The optical rate coefficients include absorption, stimulated emission, and ground-state bleach associated with the ground state and the singlet and triplet excited states as well as for the excited-state absorption between the excited states and implicit higher-energy excited states. The optical rate coefficients for continuous solar irradiance were computed using eq 3 of the main text in which the product of the individual signal components and the solar spectrum are integrated and multiplied by the fundamental optical rate coefficient. We determined the incorrect signal components were used for RuP in the published Supporting Information Table S4. The corrected Table S4 column for RuP is presented with the reported values from the original paper in the corrected Supporting Information. New simulations have been performed using the corrected values, and the results were used to update Figures 5 and 6 and also Figure S9 in the corrected Supporting Information. The published conclusions are unchanged. The populations of RuP excited states, Figure 5, are only marginally smaller, which should be expected with minor changes to the optical rate coefficients. There is not a significant change in the results for the number of radiative and nonradiative interactions per dye per second (the optical transitions and nonradiative transitions increased, respectively, by approximately 2% and 10%, Figure 6A). The occurrence of excited-state absorption (ESA) and excited-state emission (ESE) events, Figure 6C, both decreased from the original simulation results by 20% and 33%. The most notable difference is exhibited in Figure 6B; the fraction of population moving from the lowest-energy singlet state (i.e., intersystem crossing or ultrafast nonradiative relaxation) and nonradiative relaxation from the triplet state have decreased from ~0.45 to ~0.4 and increased from ~0.35 to ~0.4, respectively..

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Sunlight can turn smoldering pine wood smoke into a glass

Wildfires inject biomass burning organic aerosols (BBOA) into the atmosphere. During their lifetimes of weeks to months, they are exposed to ultraviolet (UV) irradiation. Viscosity and phase behaviour are essential properties for understanding their chemical and climate impacts. Here, we quantify changes in viscosity and phase behavior after UV exposure. After an atmospheric equivalent of 8.7 days of boundary layer UV exposure, BBOA develop a highly viscous (glassy) outer phase with a viscosity at least five orders of magnitude higher than unaged BBOA, which persists up to at least 58% relative humidity. High-resolution mass spectrometry indicates that UV-aging increases oxidation and molecular weight. Using our viscosity results, we predict that UV-aged BBOA are frequently glassy above ~2.5 km and can have viscosities up to eight orders of magnitude higher than unaged particles in some atmospheric regions, which may influence lifetimes of pollutants and brown carbon, and impact stratospheric ozone chemistry.

Golay, Zoe↗