SEARCH · Engineering Papers
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Removing labile protons via acetylation of the structural nodes in a metal–organic framework enhances catalysis at the heme linkers.
Two isomeric perylene diimide acceptors with through-space conjugated [2.2]paracyclophane as a central core show dramatic differences in device performances.
A PtCo alloy catalyst was prepared by thermal diffusion of Co encapsulated with thin N-doped carbon layers on graphitic carbon into a Pt lattice (PtCo/NGC). The Co diffused up to the near-Pt surface and resulted in an intermetallic PtCo structure without the leaching process. The intermetallic PtCo structure thermally treated under optimized conditions showed 3-fold higher mass activity than the commercial Pt/C. The potential and maximum power density loss of PtCo/NGC after 30 000 potential cycles were 34 mV and 11%, respectively, which indicated that the PtCo/NGC was remarkably stable when compared to commercial Pt/C and commercial PtCo/GC catalysts. The enhanced catalytic performance and stability of the PtCo/NGC catalyst were attributed to the formation of an intermetallic structure that alleviated the Pt oxidation and Co dissolution. The outstanding performance and stability qualify the ordered intermetallic PtCo/NGC to be a promising cathode catalyst for the commercialization of fuel cells.
The effect of metal-cluster redox identity on the thermal decarboxylation of a series of isostructural metal–organic frameworks (MOFs) with tetracarboxylate-based ligands and trinuclear μ 3 -oxo clusters was investigated.
Altering the CaO to ZnO ratio of alkali borosilicate glass, in favour of ZnO, causes phase separation with hardystonite-like (Ca 2 ZnSi 2 O 7 ) and willemite-like (ZnSi 2 O 4 ) structures identified. This is concurrent with increased glass durability.
Explore the source record for details and available documents.
Precise polyamide ionomer produces well-defined nanoscale layers.
Copper(I) iodide-based inorganic–organic hybrid semiconductors are considered promising materials for various optoelectronic applications. Here, using imidazolium bridged benzotriazoles as multidentate ligands, we designed and synthesized a series of all-in-one (AIO)-type CuI hybrid materials that hold both ionic and coordinate bonds at the interface of organic and inorganic modules. Their structures range from 0D clusters to 2D extended networks built on various molecular (0D) and chain-like (1D) anionic inorganic motifs that are interconnected through cationic ligands via multiple Cu–N bonds. Benefiting from their unique bonding nature, these compounds exhibit high stability towards heat and moisture and can be well dissolved in polar aprotic solvents. They emit low-energy light spanning from yellow to red color (550–625 nm). Finally, the electronic structure, emission mechanism, and effect of different coordination modes on their photophysical properties were studied using both experimental and theoretical methods, which has provided insight into the structure–property relationship of these inorganic–organic semiconductors.
RNA self-copying using an activated adenosine substrate is challenging. Our structure studies reveal the binding motifs of adenosine substrates. The obtained structures explain the disfavorable conformations for nucleophilic reactions.
Complementary characterization results show that chemical dissolution of transition metal in LiMn 2 O 4 is caused by solvolysis-generated HF, which can be suppresed by rational design of a group of nonsolvolytic electrolytes.
Block copolymers exhibiting an enhanced segregation strength due to an underlying high Flory–Huggins interaction parameter (high χ) have attracted considerable attention because of their potential of forming microphase-separated domains with very small feature sizes (<10 nm) useful for next-generation lithography. Here, we report the synthesis, characterization, and self-assembly of poly(styrene)- block -poly(2-vinylpyridine N -oxide) (PS- b -P2VPNO) and poly(styrene)- block -poly(4-vinylpyridine N -oxide) (PS- b -P4VPNO) block copolymers. These PS- b -PVPNOs were obtained from the oxidation of their precursors, poly(styrene)- block -poly(2-vinylpyridine) (PS- b -P2VP) and poly(styrene)- block -poly(4-vinylpyridine) (PS- b -P4VP), respectively. The PS- b -PVPNOs exhibit an enhanced segregation as revealed by ordered cylindrical and lamellar structures in the sub-10 nm scale from copolymers with relatively low molecular weight. The morphologies and periodicities of the ordered structures were determined by small-angle X-ray scattering, while atomic-force microscopy was used to image the self-assembly in thin films. Estimates of the changes in disorder–order transition temperature and domain spacing are derived from a theory based on the effects of dipolar interactions. All the experimentally observed morphological changes resulting from the oxidation of P2VP and P4VP precursors can be qualitatively explained in terms of an increased dipole moment of vinylpyridine N -oxide segments. Therefore, our results demonstrate that PVPNO based block copolymers are versatile candidates toward nanopatterned structures with small feature sizes critical for the future microelectronics industry and beyond.
Low temperature sintering enables dense composites of ceramic active materials and conductive agents. Conductivity and microstructure of composites is characterized.
Leveraging microgram-level techniques, we here present the first transplutonium bis-pentatungstate complex: NaCs 8 Cm(W 5 O 18 ) 2 ·14H 2 O (CmW 5 ).
This work summarizes various degradation mechanisms relevant for perovskite photovoltaics on different levels from the single layers over (tandem) solar cells to solar modules hereof and their mitigation strategies to enable reliable solar modules.
A fast gold nanoparticle synthesis without stabilizer in plasma–microdroplet interaction is identified.
Transition metal nitrides are promising catalysts for a variety of reactions. This work outlines their use for C 1 molecule upgrading, biomass valorization, and hydrogen evolution, and presents challenges and future opportunities for these catalysts.
Herein, we have synthesized high-performance, low-cost ionomer biocomposites comprised of sulfonated poly(ether ether ketone) (SPEEK) and softwood Kraft lignin with proton selectivities three- to ten-fold higher than that of neat SPEEK.
Aqueous Zn/MnO 2 batteries are a promising, safe alternative for grid-scale energy storage, owing to their environmentally safe and low-cost nature. The dissolution–deposition reaction mechanism in a mild aqueous pH regime has recently gained significance due to its relevance in battery design. Comprehending both the specific locations and the way reaction progresses is crucial for efficient batteries. This study demonstrates that Zinc Hydroxy Sulfate (ZHS) formed during discharge primarily near the dissolved MnO2 particles. Acting as a host for charge reactants in subsequent cycles, the charge product morphology was visualized using operando X-ray fluorescence microscopy. After ∼400 hours of cycling, capacity fade was linked to the formation of a Zn–Mn core–shell phase which is attributed to an irreversible core phase in the electrode, visualized through three-dimensional chemical mapping. Altogether, this research underscores the importance of understanding local morphological evolution in designing electrodes and chemistries for advanced grid-scale energy storage technologies.