Efficient Conversion of CO2 to CO using Tin and Other Inexpensive and Easily Prepared Post-Transition Metal Catalysts
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catalysis (heterogeneous)↗
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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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A Streamline Splitting Pore-Network Approach for Computationally Inexpensive and Accurate Simulation of Species Transport in Porous Media
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nuclear (including radiation effects), carbon sequ↗
Hybrid Solar Converters for Maximum Exergy and Inexpensive Dispatchable Electricity
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14 SOLAR ENERGY↗
A fast and reliable method for daily quality assurance in spot scanning proton therapy with a compact and inexpensive phantom
In a radiotherapy center, daily quality assurance (QA) measurements are performed to ensure that the equipment can be safely used for patient treatment on that day. In a pencil beam scanning (PBS) proton therapy center, spot positioning, spot size, range, and dose output are usually verified every day before treatments. We designed, built, and tested a new, reliable, sensitive, and inexpensive phantom, coupled with an array of ionization chambers, for daily QA that reduces the execution times while preserving the reliability of the test. The phantom is provided with 2 pairs of wedges to sample the Bragg peak at different depths to have a transposition on the transverse plane of the depth dose. Three “boxes” are used to check spot positioning and delivered dose. The box thickness helps spread the single spot and to fit a Gaussian profile on a low resolution detector. We tested whether our new QA solution could detect errors larger than our action levels: 1 mm in spot positioning, 2 mm in range, and 10% in spot size. Execution time was also investigated. Our method is able to correctly detect 98% of spots that are actually in tolerance for spot positioning and 99% of spots out of 1 mm tolerance. All range variations greater than the threshold (2 mm) were correctly detected. The analysis performed over 1 month showed a very good repeatability of spot characteristics. The time taken to perform the daily quality assurance is 20 minutes, a half of the execution time of the former multidevice procedure. This “in-house build” phantom substitutes 2 very expensive detectors (a multilayer ionization chamber [MLIC] and a strip chamber, reducing by 5 times the cost of the equipment. We designed, built, and validated a phantom that allows for accurate, sensitive, fast, and inexpensive daily QA procedures in proton therapy with PBS.
61 RADIATION PROTECTION AND DOSIMETRY↗
Below-Room-Temperature C–H Bond Breaking on an Inexpensive Metal Oxide: Methanol to Formaldehyde on CeO 2 (111)
C-H bond breaking is important for industrial commodity and specialty chemical transformations, including the upgrading of alcohols. Small primary alcohols – methanol and ethanol – are used industrially as precursors for the corresponding aldehydes at industrial scales. However, upgrading these primary alcohols involves C-H bond breaking and the processes are run at elevated temperatures (> 200 °C). In this work, new understanding from temperature programmed reaction (TPR) studies with methanol over a CeO 2 (111) surface show the C-H bond breaking and the subsequent desorption of formaldehyde, even below room temperature. This is of particular interests because CeO 2 is a naturally abundant, inexpensive metal oxide. We combine density functional theory (DFT) and kinetic Monte Carlo (KMC) to simulate the TPR of methanol on CeO 2 . Our simulations show that the low temperature C H bond breaking occurs via disproportionation of adjacent methoxy species to form methanol and formaldehyde which each then desorb. We further show from DFT calculations that the same transition state with comparably low activation energies should be possible for other sustainable primary alcohols, with ethanol, 1-propanol, and 1-butanol having been explicitly calculated. In conclusion, these findings point out a new class of transition states to search for in seeking low temperature C-H bond breaking over inexpensive metal oxides.
36 MATERIALS SCIENCE↗
Synergistic Effects of Inexpensive Mixed Metal Oxides for Catalytic Hydrothermal Liquefaction of Food Wastes
Industrial wastes and natural mixed oxide materials were evaluated as inexpensive heterogeneous catalysts for catalytic hydrothermal liquefaction (CHTL) of food wastes. Red mud and red clay achieved biocrude carbon yields of 47.0 and 39.5% with higher heating values (HHVs) of 40.2 and 37.7 MJ kg –1 , respectively, which were much greater than those without the catalyst (biocrude carbon yield of 19.7% and HHV of 36.1 MJ kg –1 ). Biocrude characterization revealed that similar families of molecules were formed in the presence and absence of catalysts, implying that the main role of the catalyst is to promote rates of thermal reactions, leading to biocrude production without opening new pathways. The crystalline structures of inexpensive mixed oxides were stable under hydrothermal conditions, with modest calcium leaching (7.5%) and trace leaching of other metals. Using red clay or red mud resulted in >40% recovery of the energy in food waste as biocrude, greater than that obtained under noncatalytic conditions (18%) or from any individual constituent oxide (19–27%). The improved CHTL performance of the mixed metal oxides compared with single-metal oxides was attributed to the synergistic effects of base and acid sites present on catalyst surfaces; mixed oxides presented balanced densities of acids and bases, whereas the constituent oxides were either primarily acidic or primarily basic. Lastly, the percent of energy recovered as biocrude oil was strongly correlated with the base-to-acid site density ratio, providing an important performance predictor for CHTL conversion of food waste to bioenergy.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition
We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ∼10{sup 7 }cm{sup −2}. Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm{sup 2}/V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Innovative, Inexpensive Etching Technique Developed for Polymer Electro- Optical Structures
Electro-optic, polymer-based integrated optic devices for high-speed communication and computing applications offer potentially significant advantages over conventional inorganic electro-optic crystals. One key area of integrated optical technology--primary processing and fabrication--may particularly benefit from the use of polymer materials. However, as efforts concentrate on the miniaturization of electro-integrated circuit pattern geometries, the ability to etch fine features and smoothly sloped sidewalls is essential to make polymers useful for electro-integrated circuit applications. There are many existing processes available to etch polymer materials, but they all yield nearly vertical sidewalls. Vertical sidewalls are too difficult to reliably cover with a metal layer, and incomplete metalization degrades microwave performance, particularly at high frequency. However, obtaining a very sloped sidewall greatly improves the deposition of metal on the sidewall, leading to low-loss characteristics, which are essential to integrating these devices in highspeed electro-optic modulators. The NASA Lewis Research Center has developed in-house an inexpensive etching technique that uses a photolithography method followed by a simple, wet chemical etching process to etch through polymer layers. In addition to being simpler and inexpensive, this process can be used to fabricate smoothly sloped sidewalls by using a commercial none rodible mask: Spin-On-Glass. A commercial transparent material, Spin-On-Glass, uses processes and equipment similar to that for photoresist techniques.
Nguyen, Hung D.↗
Achieving zT > 1 in Inexpensive Zintl Phase Ca 9 Zn 4+ x Sb 9 by Phase Boundary Mapping
Complex multinary compounds (ternary, quaternary, and higher) offer countless opportunities for discovering new semiconductors for applications such as photovoltaics and thermoelectrics. However, controlling doping has been a major challenge in complex semiconductors as there are many possibilities for charged intrinsic defects (e.g., vacancies, interstitials, antisite defects) whose energy depends on competing impurity phases. Even with compounds with no apparent deviation from a stoichiometric nominal composition, such defects commonly lead to free carrier concentrations in excess of 1020 cm -3 . Nevertheless, by slightly altering the nominal composition, these defect concentrations can be tuned with small variation of the chemical potentials (composition) of each element. While the variation of chemical composition is undetectable, it is shown that the changes can be inferred by mapping (in nominal composition space) the boundaries where different competing impurity phases form. In the inexpensive Zintl compound Ca 9 Zn 4+x Sb 9 , the carrier concentrations can be finely tuned within three different three-phase regions by altering the nominal composition (x = 0.2–0.8), enabling the doubling of thermoelectric performance (zT). Because of the low thermal conductivity, the zT can reach as high as 1.1 at 875 K, which is one of the highest among the earth abundant p-type thermoelectrics with no ion conducting.
36 MATERIALS SCIENCE↗
Metal–Nitrogen–Carbon Cluster–Decorated Titanium Carbide is a Durable and Inexpensive Oxygen Reduction Reaction Electrocatalyst
Clusters of nitrogen- and carbon-coordinated transition metals dispersed in a carbon matrix (e. g., Fe-N-C) have emerged as an inexpensive class of electrocatalysts for the oxygen reduction reaction (ORR). In this work, it was shown that optimizing the interaction between the nitrogen-coordinated transition metal clusters embedded in a more stable and corrosion-resistant carbide matrix yielded an ORR electrocatalyst with enhanced activity and stability compared to Fe-N-C catalysts. Utilizing first-principles calculations, an electrostatics-based descriptor of catalytic activity was identified, and nitrogen-coordinated iron (FeN 4 ) clusters embedded in a TiC matrix were predicted to be an efficient platinum-group metal (PGM)-free ORR electrocatalyst. Guided by theory, selected catalyst formulations were synthesized, and it was demonstrated that the experimentally observed trends in activity fell exactly in line with the descriptor-derived theoretical predictions. The Fe-N-TiC catalyst exhibited enhanced activity (20 %) and durability (3.5-fold improvement) compared to a traditional Fe-N-C catalyst. It was posited that the electrostatics-based descriptor provides a powerful platform for the design of active and stable PGM-free electrocatalysts and heterogenous single-atom catalysts for other electrochemical reactions.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Computationally inexpensive part-scale thermal history of additive friction-stir deposition
This study presents an analytical model for steady-state power generation and tool heat loss in additive friction-stir deposition (AFSD), developed to enable part-scale thermal simulation while remaining computationally inexpensive. The model predicts total generated power, yielding 3.7–4.7 kW across deposition temperature setpoints of 400–460 °C for the deposition of AA6061 with a Be-Cu tool. This corresponds to 90–95% of the reported spindle power. Tool heat loss is experimentally determined by calibrating a steady-state energy balance between the generated power, the substrate-deposition thermal gradient, and a temperature dependent tool heat loss term: q tool (T) = a + b (T - 400°C) with a = 2.7 x 10 6 Wm -2 and b = 9.5 x 10 3 Wm -2 K -1 . The calibration indicates that about 69% of the generated heat is conducted into the tool for this configuration, which is much higher than previously reported. The calibrated heat-source is implemented in finite element software (Adamantine) to simulate the transient thermal history of a 100 cm 3 representative build in 8 min on a standard desktop (at 0.635 mm build-height resolution). For the first three layers, the substrate temperatures between simulation and experiment are within 10% mean absolute percentage error. Sensitivity analysis indicates that uncertainties in average deposition temperature and deformation localization (stir-zone geometry, depth, and spatial dependance of strain-rate and flow stress) dominate model variance, motivating additional experimental verification.
Additive Friction-Stir Deposition↗
Preparation of Porous Nanofibers from Electrospun Polyacrylonitrile/Polyvinylidene Fluoride Composite Nanofibers by Inexpensive Salt Using for Dye Adsorption
The high surface area of porous nanofibers enhances their performance for many applications. The present study investigated electrospinning and dye adsorption properties of polymeric nanofibers which were porous by various types of salts. The salt/polyacrylonitrile/polyvinylidene fluoride composite nanofibers were electrospun, and the inexpensive salts such as sodium chloride (NaCl), sodium bicarbonate (NaHCO{sub 3}), or calcium chloride (CaCl{sub 2}) was used to manufacture the porous fibers. Subsequently, the salt was removed by a selective dissolution, and salt extraction of nanofibers was performed with the solution of hydrochloric acid (10 wt%). Salt/PVDF/PAN and porous PVDF/PAN composite nanofibers have been applied to dye adsorption of solution. The characteristics of nanofibers were studied by Fourier transform infrared microscopy (FTIR) and scanning electron microscopy (SEM) analysis. FTIR showed that the salt was extracted from PVDF/PAN nanofibers successfully, and SEM indicated that many pores were aligned with the nanofibers. The adsorption capacity of salt nanofibers webs and porous nanofibers webs for Basic Blue 41 were compared with each other, and porous fibers were obtained from NaHCO{sub 3} having the highest dye adsorption value. Adsorption of dyes follows the Langmuir isotherm and pseudo-second order kinetics.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Chapter 12 - Addressing Groundwater Fluoride Contamination Using Inexpensively Processed Bauxite
Globally, 200 million people are at risk of adverse health effects from drinking groundwater contaminated with high fluoride concentrations that exceed the World Health Organization's maximum contaminant limit (WHO MCL=1.5ppmF-). Although many defluoridation technologies have been demonstrated to work in lab, most have proven inappropriate for impoverished rural regions of developing countries because they are cost-prohibitive, require skilled labor, or are difficult to scale. The authors submit evidence for the use of bauxite, an aluminum-rich ore, as a potentially inexpensive, effective, and scalable defluoridation technology. Specifically, we present results from experimental studies that characterize globally diverse bauxite ores, elucidate fluoride removal mechanisms, and establish proof of concept that mildly processed bauxite can cost-effectively remediate field-relevant fluoride concentrations in synthetic and real groundwater matrices at field-relevant kinetics. We discuss practical implications of these research findings and highlight remaining challenges and unknowns that need to be further studied before implementing the proposed defluoridation process in the field.
Gadgil, AJ↗
Mixed rare earth oxides derived from monazite sand as an inexpensive precursor material for room temperature magnetic refrigeration applications
Highlights: • Compound is synthesized using mixed rare earth oxide derived from monazite sand. • Rietveld refinement confirms the compound is a mixture of rare earth manganites and CeO{sub 2}. • The compound exhibits a magnetic entropy change of 3.28 J kg{sup −1} K{sup −1} under 50 kOe magnetic field at 310 K. • The compound exhibit a RCP of 120 J kg{sup −1} and ΔT{sub ad} of 2.11 K at 310 K under 50 kOe field. - Abstract: An inexpensive perovskite type (RE{sub MIX}){sub 0.67}Sr{sub 0.33}MnO{sub 3} compound is synthesized via solid state method using mixed rare earth oxide precursor derived from monazite sand. Rietveld refinement of X-ray powder diffraction patterns confirms the compound is a mixture of rare earth manganites which is the major phase and CeO{sub 2} as the secondary phase. The compound shows a second order ferromagnetic to paramagnetic transition near room temperature and exhibits a magnetic entropy change (-ΔS{sub M}) of 3.28 J kg{sup −1} K{sup −1} with a relative cooling power (RCP) of 120 J kg{sup −1} and an adiabatic temperature change (ΔT{sub ad}) of 2.11 K at 310 K under 50 kOe magnetic field. The Debye temperature of the compound is found to be 543 K and room temperature thermal conductivity is 4.26 W m{sup −1} K{sup −1}. The temperature variation of electrical resistivity shows a metal to insulator transition around 180 K, which gets shifted towards higher temperature upon the application of magnetic field. The compound shows a large value of −ΔS{sub M} and this work makes an endeavor to develop low–cost materials for the magnetic refrigeration applications near the room temperature.
36 MATERIALS SCIENCE↗
Intrinsically sodiophilic, mesoporous metal-free wetting layers based on inexpensive carbon black for sodium-metal batteries
In this article, elevated temperature molten Na batteries are seeing a resurgence of interest for low-cost electrochemical energy storage for the grid. Of the many recent innovations in this battery concept, new methods focused on intermediate temperature operation (e.g. 110–190 °C) have gained prominence as a way to enable comparable performance with less thermal energy loss and lower-cost materials of construction. However, the poor wettability of molten Na on suitable solid-electrolyte separators such as sodium Beta Alumina Solid-Electrolyte (Na-β”-Al 2 O 3 , ‘BASE’) requires continued innovation in interface engineering to promote full utilization of the solid-electrolyte surface area and minimize cell resistance. There have been many successful approaches to improve Na-wettability to-date including heat treatment in an inert atmosphere to remove adsorbed surface species, deposition of alloying metals such as Pb, Sn, or Bi, and use of carbon-based interfacial layers. However, these approaches either lack the ability to provide good wetting at very low temperatures (near the melting point of Na) or rely on non-scalable processes and/or toxic/expensive metals. To solve these issues, a new carbon-based sodiophilic treatment is demonstrated, which utilizes inexpensive components to form a meso/macroporous sodiophilic layer, is easily applied via drop-casting or spray-coating, provides excellent wetting as low as 110 °C, and is completely metal-free. It is found that the good sodium wetting can be attributed to the wider range of pore sizes in the carbon layers demonstrated in this study. Na wetting may occur as surface tension is initially broken by larger pores, followed by the intrusion of molten Na into smaller pores due to the apparent intrinsic affinity of Na-metal for carbon surfaces, in conjunction with the capillarity effect. Low cell-level area specific resistances of 20–30 and 13–15 Ω·cm 2 are demonstrated at 110 and 140 °C respectively. Finally, the utility of this metal-free wetting layer for solid-Na anodes is explored, showing that the metal-free wetting layer can reach a critical current density of 1.88 mA·cm -2 at 30 °C.
25 ENERGY STORAGE↗
Feedstocks to Pharmacophores: Cu-Catalyzed Oxidative Arylation of Inexpensive Alkylarenes Enabling Direct Access to Diarylalkanes
A Cu-catalyzed method has been identified for selective oxidative arylation of benzylic C–H bonds with arylboronic esters. The resulting 1,1-diarylalkanes are accessed directly from inexpensive alkylarenes containing primary and secondary benzylic C–H bonds, such as toluene or ethylbenzene. All catalyst components are commercially available at low cost, and the arylboronic esters are either commercially available or easily accessible from the commercially available boronic acids. In conclusion, the potential utility of these methods in medicinal chemistry applications is highlighted.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
An inexpensive technique for the time resolved laser induced plasma spectroscopy
We present an efficient and inexpensive method for calculating the time resolved emission spectrum from the time integrated spectrum by monitoring the time evolution of neutral and singly ionized species in the laser produced plasma. To validate our assertion of extracting time resolved information from the time integrated spectrum, the time evolution data of the Cu II line at 481.29 nm and the molecular bands of AlO in the wavelength region (450–550 nm) have been studied. The plasma parameters were also estimated from the time resolved and time integrated spectra. A comparison of the results clearly reveals that the time resolved information about the plasma parameters can be extracted from the spectra registered with a time integrated spectrograph. Our proposed method will make the laser induced plasma spectroscopy robust and a low cost technique which is attractive for industry and environmental monitoring.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗