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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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Here we summarize the progress of developing crystalline porous framework materials with supramolecular macrocycles for their applications in the solid state, guiding the readers through their future chemistry, applications and commercialization.
Correction for ‘Porous bipolar polymers as organic cathodes for sustainable sodium/potassium-ion batteries’ by Motahareh Mohammadiroudbari et al. , J. Mater. Chem. A , 2023, https://doi.org/10.1039/D3TA02445H.
By controlling the ratio of end groups in a series of porous organic polymers, we maximized their cobalt adsorption capacity.
A new stable three-dimensional (3D) porous and metallic boron nitride anode material is proposed, exhibiting good ductility for sodium-ion batteries (SIBs).
The incorporation of different functional fillers into the DIW composite resin can expand the functionality of 3D printed porous materials for different applications.
The magnesiothermic reduction is an important reaction as it is a bulk method that produces porous Si for a wide range of applications directly from SiO 2 .
Controlled growth of porous, optically transparent thin films reveals structure- and thickness-dependent effects and enablesin situstudy of post-synthetic metalation kinetics.
Flow and motility type determine bacterial transport in porous media. Peritrichous bacteria outperform piliated and monotrichous types in maintaining motility (cross-streamline movement) under high-flow conditions.
Practical catalysts with a porous framework, such as zeolites, host catalytic reactions at active sites engrained in the pores and channels of the scaffold. The mechanism of interaction at these active sites, defining catalyst performance, remains elusive, in large part, due to the lack of surface characterization methods available for thick films or powders. Here, we present thin film analogs of practical catalysts that allow for the implementation of surface characterization tools, including advanced microscopy and operando spectroscopy methodologies. Specifically, we investigated bilayer silica, MFI nanosheets, and UiO-66 thin films using a multi-modal approach addressing film growth, characterization, and gas adsorption aimed at understanding catalytic activity, reactivity, and selectivity properties, as defined by molecular-level changes in the reaction mechanism.
We report deflagration-to-detonation transition phenomena in cylindrical columns of porous explosives based on octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). The HMX powder and LX-14 (95.5 wt. % HMX and 4.5 wt. % estane polyurethane) prills were observed with high-speed cameras and flash x rays under conditions that allow for precise scaling and registration of the recorded images. These experimental results test the conventional assumption of axisymmetric, effective one-dimensional burning. Polycarbonate confinement tubes allowed this direct imaging with steel spheres employed as radio-opaque fiducials. Spheres embedded in the explosive column revealed the displacement of the explosive prior to deflagration. X-ray and fast camera images show that a dense plug of compact explosive develops ahead of the deflagration front. The internal fiducials register both internal changes in the plug and changes in the position between successive x-ray images. Tantalum witness strips placed on the inner wall of the explosive channel revealed radial expansion of the tube bore at successive x-ray exposures, indicating the internal pressure of about 100 MPa just before detonation. Images indicate that the deflagration is not only asymmetric but also involves newly observed transient phenomena just before detonation. Furthermore, we typically see a brief but continuous increase in deflagration speed and the formation of a deflagration channel that bypasses the plug just prior to detonation. We hypothesize that these phenomena play an important role in the deflagration-to-detonation transition itself.
Slippery liquid-infused porous surfaces (SLIPSs) have been explored for many applications, taking advantage of their highly non-wetting property. In this work, we explore the SLIPS as a cladding material for waveguiding. SLIPSs are prepared by infusing perfluoropolyether oil to hydrophobized nanoporous surfaces of silicon. Power loss and transmission efficiency of an HeNe laser (1.82 mW and 632.8 nm) with varying incident angles were measured through microchannels consisting of the SLIPSs as cladding layers (noil = 1.30) and water (nwater = 1.33) as a core, compared to other cladding types including a planar silicon surface and the nanoporous surfaces in hydrophilic (Wenzel state) and hydrophobic (Cassie–Baxter state) conditions with no oil infused. Agreeing with Snell's law, a total internal reflection occurs at the incident angle as high as 14° for the SLIPSs. The waveguide loss at 14° is only 1.8 dB/cm for the SLIPSs, while those for planar silicon, hydrophilic nanoporous, and hydrophobic nanoporous surfaces are 5.9, 7.4, and 4.9 dB/cm, respectively. The power transmission efficiency of the SLIPSs is independent of the porosity because the surfaces are fully covered with the oil layer, whereas those of hydrophilic and hydrophobic nanoporous surfaces, whose pores are filled with water and air, respectively, depend on the porosity. The significantly lower power loss and the insensitivity to the surface porosity are advantages of the SLIPSs over the other surfaces and can benefit in waveguiding applications such as optofluidics.
Significance Electronic waste, also called e-waste, is rapidly becoming a major industrial hazard because of the increased use of circuits and screens. With the right technology, however, this waste could become a sustainable source for precious metals. Such a solution requires selectivity toward the precious metals, as this characteristic is even more important than capacity. A porphyrin-based porous polymer with selective binding shows remarkable selectivity and a reductive mechanism, a combination which makes for record-high recycling of precious metals––particularly gold––from e-waste.
The conversion of CO 2 into fuels and chemicals is an attractive option for mitigating CO 2 emissions. Controlling the selectivity of this process is beneficial to produce desirable liquid fuels, but C–C coupling is a limiting step in the reaction that requires high pressures. Here, we propose a strategy to favor C–C coupling on a supported Ru/TiO 2 catalyst by encapsulating it within the polymer layers of an imine-based porous organic polymer that controls its selectivity. Such polymer confinement modifies the CO 2 hydrogenation behavior of the Ru surface, significantly enhancing the C 2+ production turnover frequency by 10-fold. We demonstrate that the polymer layers affect the adsorption of reactants and intermediates while being stable under the demanding reaction conditions. Our findings highlight the promising opportunity of using polymer/metal interfaces for the rational engineering of active sites and as a general tool for controlling selective transformations in supported catalyst systems.
A method is presented for synthesizing core–shell nanoparticles with a magnetic core and a porous shell suitable for drug delivery and other medical applications. The core contains multiple γ -Fe 2 O 3 nanoparticles (~15 nm) enclosed in a SiO 2 (~100–200 nm) matrix using either methyl (denoted TMOS- γ -Fe 2 O 3 ) or ethyl (TEOS- γ -Fe 2 O 3 ) template groups. Low-temperature Mössbauer spectroscopy showed that the magnetic nanoparticles have the maghemite structure, γ -Fe 2 O 3 , with all the vacancies in the octahedral sites. Saturation magnetization measurements revealed that the density of γ -Fe 2 O 3 was greater in the TMOS- γ -Fe 2 O 3 nanoparticles than TEOS- γ -Fe 2 O 3 nanoparticles, presumably because of the smaller methyl group. Magnetization measurements showed that the blocking temperature is around room temperature for the TMOS- γ -Fe 2 O 3 and around 250 K for the TEOS- γ -Fe 2 O 3 . Three dimensional topography analysis shows clearly that the magnetic nanoparticles are not only at the surface but have penetrated deep in the silica to form the core–shell structure.
Abstract The tungsten fuzz growth under non-erosive and erosive helium plasmas in the linear plasma device PISCES-A has been investigated by experiments and simulations. The simulation results benchmarked against the experimental measurements indicate a decayed net physical sputtering yield during fuzz growth under the erosive helium plasma. Further, a nonlinear dependence of the net tungsten erosion on the ‘effective’ porous nanostructure that can be sputtered by incident helium particles has been found.
SUMMARY This paper presents a novel thermodynamically consistent constitutive model for partially saturated porous rocks across a wide range of conditions. The material states generated behind the shock wave from an explosive source can vary significantly, ranging from crushed and melted rock near the source to a poroelastic medium in the far field. In the model, rock strength is determined by the effective pressure, which is calculated using two independent equations of state: one for the solid rock and another for the pore fluid. The model accounts for shock-induced liquefaction resulting from fluid pressure buildup in the pore spaces near the explosive source. Simultaneously, it describes the increase in wave propagation speed due to elastic pore contraction in both dry and partially saturated rocks. This model is applied to investigate how fluid saturation affects the amplitude and shape of the generated waves, as well as the residual stress surrounding the cavity formed by spherical explosions.
A simple and effective way to enhance PCM thermal conductivity is by embedding porous materials with high thermal conductivities. In this work, CFD was used to evaluate the melting of PCM embedded in metal foam supplied with constant heat flux. Good agreement between experimental and numerical results has been found with a mean PCM local temperature deviation of 1.62K and 2.97K in two locations. The CFD simulation time was 56 hours for 6.5 hours of flow time. A computationally efficient resistance capacitance-based model (RCM) was developed to improve simulation speed. The proposed RCM exhibited mean local temperature deviations of 1.86K and 2.96K when compared against the experimental data for two thermocouple positions, however, it was approximately 2.5x10 5 times faster than CFD. The charging time deviation was less than 1% compared to CFD, and no significant change in thermal energy stored was observed since the temperature differences were small enough to result in insignificant sensible heat deviation. A simulation cost-effectiveness index (CEI) considering accuracy and computational affordability was introduced; the CEI of the RCM solver is 10 3 times better compared to CFD for the prediction of local PCM temperature.
Abstract Metal‐supported solid oxide fuel cells (MS‐SOFCs) have been fabricated by applying phase‐inversion tape‐casting and atmospheric plasma spraying (APS). The effect of the binder amount of the phase‐inversion slurries on the microstructure development of the 430L stainless steel metal support was investigated. The pore structures, the viscosity of the slurry, porosity and permeability of the as‐prepared metal supports are significantly influenced by the amount of the binder. NiO–scandia‐stabilized zirconia (ScSZ) anode, ScSZ electrolyte and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ (LSCF) cathode layers were consecutively deposited on the metal support with an ideal microstructure by APS process. The effect of plasma power of the APS on the microstructure of the electrolyte and cathode was investigated. A dense electrolyte layer and a porous cathode layer were successfully obtained at 40 and 6 kW of the APS plasma power, respectively. MS‐SOFCs, with a cell configuration of 430L/Ni‐ScSZ/ScSZ/LSCF, achieved a maximum cell power density of 1079 mW cm −2 at 700°C using humidified H 2 as fuel and ambient air as oxidant. The corresponding ohmic resistance and total resistance of MS‐SOFCs was 0.14 and 0.32 Ω cm 2 , respectively. This work demonstrates the feasibility of fabricating high‐performance MS‐SOFCs with economical and scalable techniques.