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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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This work provides new insight into the backbone configurations of A-D-A-type acceptors. Two isomers have significant difference in optical and electric properties, resulting in a major impact on the current density and fill factor of the devices.
In this work, the P2-type layered material Na 2/3 [Ni 1/3 Ti 2/3 ]O 2 was studied as a promising bi-functional electrode material for sodium-ion batteries. To assess the electrochemical performance of this material, we investigated the diffusion mechanism as well as ionic and electronic conductivity with a combination of experimental and computational techniques. The quasi-elastic neutron scattering (QENS) experiments and first-principles molecular dynamics (FPMD) simulations were performed to identify the diffusion mechanism. The QENS data showed that Na ion diffusion can be well described by the Singwi–Sjölander jump diffusion model, where the obtained mean jump length matched the distances between the neighboring edge-share and face-share Na sites. FPMD predicted diffusivity values similar to those from QENS. The computed composition dependence of ionic and electronic conductivity of Na x [Ni 1/3 Ti 2/3 ]O 2 suggested that electronic conductivity changes significantly when x deviates from 2/3 as the redox couple of Ni and Ti is activated, while the change of ionic conductivity with x is relatively small.
Control H- and J-aggregation of non-fullerene acceptor and research their different influence on photovoltaic performance.
The photophysical and photochemical properties of two Pt(IV)Re(I) conjugates were studied via both experimental and computational methods. Additionally, both conjugates exhibit modest photocytotoxicity against ovarian cancer cells. X-ray fluorescence microscopy showed that Pt and Re colocalize in cells whether they had been irradiated or not. This work demonstrates the potential of photoactivated multilimetallic agents for combating cancer.
From X-ray absorption spectroscopy (XAS) and X-ray photoemission spectroscopy (XPS) it is evident that the spin state transition behavior of Fe( ii ) spin crossover coordination polymer crystallites at the surface differs from the bulk.
Anions cannot have Rydberg states, but anions with polar neutral cores can support highly diffuse dipole-bound states (DBSs) as a class of interesting electronically excited states below the electron detachment threshold. The binding energies of DBSs are extremely small, ranging from a few to few hundred wavenumbers and generally cannot support bound vibrational levels below the detachment threshold. Thus, vibrational excitations in the DBS are usually above the electron detachment threshold and they have been used to conduct resonant photoelectron spectroscopy, which is dominated by state-specific autodetachment. Here we report an investigation of a cryogenically-cooled complex anion, the enantiopure (R)-(–)-1-(9-anthryl)-2,2,2-trifluoroethanolate (R-TFAE–). The neutral R-TFAE radical is relatively complex and highly polar with a non-planar structure (C 1 symmetry). Photodetachment spectroscopy reveals a DBS 209 cm–1 below the detachment threshold of R-TFAE– and seven bound and eight above-threshold vibrational levels of the DBS. Resonant two-photon detachment (R2PD) via the bound vibrational levels of the DBS exhibits strictly adiabatic photodetachment behaviors by the second photon, in which the vibrational energies in the DBS are carried to the neutral final states, because of the parallel potential energy surfaces of the DBS and the corresponding neutral ground electronic state. Relaxation processes from the bound DBS levels to the ground and low-lying electronically excited states of R-TFAE– are also observed in the R2PD photoelectron spectra. Finally, the combination of photodetachment and resonant photoelectron spectroscopy yields frequencies for eight vibrational modes of the R-TFAE radical.
Recently, diimine Re( I ) tricarbonyl complexes have attracted great interest due to their promising cytotoxic effects. Here, we compare the cytotoxicity and cellular uptake of two Re( I ) compounds fac -[(Re(CO) 3 (bpy)(H 2 O)](CF 3 SO 3 ) ( 1 ) and Na( fac -[(Re(CO) 3 (bpy)(S 2 O 3 )])·H 2 O (bpy = 2,2'-bipyridine) ( 2 ). The Re-thiosulfate complex in 2 was characterized in two solvated crystal structures {Na( fac -[Re(CO) 3 (bpy)(S 2 O 3 )])·1.75H 2 O·C 2 H 5 OH} 4 ( 2 + 0.75H 2 O + C 2 H 5 OH) 4 and ( fac -[Re(CO) 3 (bpy)(H 2 O)]) ( fac -[Re(CO) 3 (bpy)(S 2 O 3 )])·4H 2 O ( 3 ). The cytotoxicity of 1 and 2 was tested in the MDA-MB-231 breast cancer cell line and compared with that of cisplatin. The cellular localization of the Re( I ) complexes was investigated using synchrotron-based X-ray fluorescence microscopy (XFM). Overall, the results show that replacement of the aqua ligand with thiosulfate renders the complex less toxic most likely by distrupting its cellular entry. As a result, thiosulfate could potentially have a similar chemoprotective effect against diimine fac -Re(CO) 3 complexes as it has against cisplatin.
High-resolution photoelectron imaging and photodetachment spectroscopy of cryogenically cooled pyrrolide and imidazolide anions are used to probe the electronic structure and spectroscopy of pyrrolyl and imidazolyl radicals. The high-resolution data allow the ground state vibronic structures of the two radicals to be completely resolved, yielding accurate electron affinities of 2.1433 ± 0.0008 eV and 2.6046 ± 0.0006 eV for pyrrolyl and imidazolyl radicals, respectively. Fundamental frequencies for eight vibrational modes of pyrrolyl and ten vibrational modes of imidazolyl are measured, including several nonsymmetric Franck–Condon-forbidden modes. Two electronic excited states are also observed for the two radicals, displaying diffuse spectral features in both systems. The observations of nonsymmetric vibrational modes in the ground states and the diffuse excited state features provide strong evidence for vibronic couplings between the ground state and the two close-by excited states. The 2-pyrrolide isomer is also observed as a minor species from the electrospray ionization source and the electron affinity of 2-pyrrolyl is measured to be 1.6690 ± 0.0030 eV along with five vibrational frequencies. Even though the HOMOs of both pyrrolide and imidazolide anions are p orbitals, photodetachment spectroscopy reveals completely different threshold behaviors for the two anions: a d-wave-dominated spectrum for pyrrolide and an s-wave-dominated spectrum for imidazolide. Furthermore, the current study provides a wealth of electronic and spectroscopic information, which is ideal to compare with more accurate vibronic coupling calculations for these two important radicals, as well as interesting information about the photodetachment dynamics of the two anions.
The treatment of toluene solvent and DTT additive enables the PBQ6:PYF-T- o -based all-PSC devices with PCE up to 17.06%, which is one of the highest value in non-halogenated-processed all-PSCs to date.
A joint spectroscopy and ab initio study identifies electronic orbitals of valence tautomeric complexes on different semiconducting polymers, including a spin-polarized ligand-to-metal charge transfer state that spans the entire molecular plane.
The oxygen evolution reaction (OER) requires electrodes that are not only catalytically active, but also stable under harsh electrochemical environments to enable efficient, durable technologies. Our recent report of a stable amorphous Ni 0.5 Sb 0.5 O z OER photoanode established Ni–Sb–O as an important system for computational understanding of both the structural and catalytic behavior of these complex oxides. In the present work we show that Ni x Sb 1-x O z with x > 0.33 crystallizes into a previously unknown phase. Guided by experimental X-ray diffraction, here, we use density functional theory calculations to perform a prototype phase search to identify a broad family of stable and metastable mixed rutile and hexagonal-like phases for x = 0.33, 0.50, and 0.66 compositions. For the identified phases, we predict favorable oxygen vacancy formation energies for Ni-rich compositions under the reducing synthesis conditions which match measured Ni K-edge X-ray absorption spectra. The calculated overpotential for the most active site decreases with increasing Ni content, from 0.91 V (x = 0.33) to 0.49 V (x = 0.66), which captures the experimentally observed trend. We find the active site changes from the Ni–O–Sb bridge to a Ni–O–Ni bridge at increasing Ni concentrations, rather than the commonly studied singly under-coordinated sites. Finally, detailed Pourbaix analysis of the identified phases show excellent electrochemical stability, consistent with experimentally measured low metal ion concentrations in the electrolyte of photoelectrochemical cells. Collectively, our consideration of an ensemble of structures enables identification of the most catalytically prolific structural motifs, aiding the understanding of crystalline and amorphous catalysts and elucidating the co-optimization of activity and durability in nickel antimonates.
Human researchers multi-task, collaborate, and share resources. HELAO-async is a multi-workflow automation software that helps realize these attributes in materials acceleration platforms.
The sustainability potential of carbon capture, concentration, and utilization technologies motivates accelerated discovery of carbon dioxide sorbents, for which we present a high throughput screening instrument.
The utilization of sustainable lignin to synthesize wood adhesives has attracted increasing attention in recent years. However, the facile fabrication of strong and environmentally friendly lignin-based adhesives with a high lignin content remains a significant challenge. In this study, we developed a formaldehyde-free wood adhesive system by combining alkali lignin and poly(propylene glycol) bis(2-aminopropyl ether). The process of producing lignin-based adhesives involves a simple mixing of wood flour, lignin, and a commercially available crosslinker (polyetherimide), followed by direct hot-pressing into particleboards. The lignin-based adhesive showed a high biomass content of 75 wt% (crosslinker accounting for 25 wt%) and the internal bonding strength of the formaldehyde-free and non-toxic particleboards was 1.42 MPa, outperforming many other bio-based adhesives. In conclusion, the study demonstrates a new and facile strategy to synthesize a lignin-based thermoset that is readily and practically applicable as an adhesive to fabricate high-performance, high lignin content, and formaldehyde-free wood products.
As the richest aromatic renewable resource, lignin has attracted significant attention for fabricating various materials. However, due to lignin's structural complexity, an effective and facile structural modification strategy remains a substantial challenge. Herein, we have successfully applied photoinitiated reversible addition–fragmentation chain transfer (RAFT) as a versatile tool to synthesize amphiphilic lignin copolymers with lignin derivatives as the macroinitiator. The experimental and density functional theory analysis systematically investigated the photopolymerization kinetics, proving excellent control over molecular weights. Additionally, 1 H NMR and FT-IR analyses confirmed the well-designed structures. Moreover, the structures of copolymers were tunable by simple variations of monomer structures. Finally, the self-assembly of the synthesized copolymers into nanoparticles was explored, together with the potential applications as Pickering emulsion stabilizers. Finally, we believe that this work will offer a facile and green approach to synthesize lignin-based novel copolymers and further expand its applications.
Size-dependent diffusion of supported faceted nanoclusters is mediated by disassembly & reassembly of outer layers of facets. A mean-field picture (random independent motion of surface atoms) fails to capture behavior.
We present ionization as a novel method for improving perovskite solar cells performance. The ionic HTMs give higher efficiency than the non-ionic derivative due to improved interfacial properties, defect passivation, and ideal surface topographies.
We present an automated platform for studying electrode corrosion as a function of electrochemical history and electrolyte composition using Pt ORR as a proof-of-concept relevant to next-generation phosphoric acid fuel cells.