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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Polymer‐Based Ruthenium(II) Polypyridyl Chromophores on TiO 2 for Solar Energy Conversion

Abstract A polychromophoric light‐harvesting assembly featuring a polystyrene (PS) backbone with ionic carboxylate‐functionalized Ru II polypyridyl complexes as pendant groups (PS‐Ru‐A) was synthesized and successfully anchored onto mesoporous structured TiO 2 films (TiO 2 //PS‐Ru‐A). Studies of the resulting TiO 2 //PS‐Ru‐A films carried out by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) confirmed that the ionic carboxylated Ru II complexes from PS‐Ru‐A led to the surface immobilization on the TiO 2 film. Monochromatic light photocurrent spectroscopy (IPCE) and white light (AM1.5G) current–voltage studies of dye‐sensitized solar cells using the TiO 2 //PS‐Ru‐A photoanode give rise to modest photocurrent and white light efficiency (24 % peak IPCE and 0.33 % PCE, respectively). The photostability of surface‐bound TiO 2 //PS‐Ru‐A films was tested and compared to a monomeric Ru II complex (TiO 2 //Ru‐A), showing an enhancement of ∼14 % in the photostability of PS‐Ru‐A. Transient absorption measurements reveal that electron injection from surface‐bound pendants occurs on the picosecond time scale, similar to TiO 2 //Ru‐A, while time‐resolved emission measurements reveal delayed electron injection occurring in TiO 2 //PS‐Ru‐A on the nanosecond time scale, underscoring energy transport from unbound to surface‐bound complexes. Additionally, charge recombination is delayed in PS‐Ru‐A, pointing towards intra‐assembly hole transport to complexes away from the surface. Molecular dynamics simulations of PS‐Ru‐A in fluid solution indicate that a majority of the pendant Ru II complexes lie within 10–20 Å of each other, facilitating efficient energy‐ and charge transport among the pendant complexes.

Leem, Gyu↗
DOE OSTI2012

Soft Magnetic Materials in High-Frequency, High-Power Conversion Applications

Advanced soft magnetic materials are needed to match high-power density and switching frequencies made possible by advances in wide band-gap semiconductors. Magnetics capable of operating at higher operating frequencies have the potential to greatly reduce the size of megawatt level power electronics. In this article, we examine the role of soft magnetic materials in high-frequency power applications and we discuss current material's limitations and highlight emerging trends in soft magnetic material design for high-frequency and power applications using the materials paradigm of synthesis -> structure -> property -> performance relationships.

Leary, AM↗
DOE OSTI2015

Optimization of renewable pinene production from the conversion of macroalgae Saccharina latissima

The enzymatic hydrolysis of Saccharina latissima with laminarinase was compared to hydrolysis with different combinations of cellulase and hemicellulase enzyme mixtures. The hemicellulase mixture resulted in similar release of glucose, while the cellulase mixture released 40% more glucose than laminarinase alone. The combination of a laminarinase augmented with a cellulase mixture resulted in a 53% increase of glucose release from S. latissima than laminarinase. Increasing biomass loading above 4% (w/v) reduced the sugar yield. Resulting macroalgae hydrolysates were used as a carbon source for the production of pinene, making use of a novel two plasmid Escherichia coli system. The macroalgal hydrolysates were suitable for the novel microbial production of pinene with no further treatment and/or purification.

59 BASIC BIOLOGICAL SCIENCES↗