Laser-Induced Graphene Composites for Printed, Stretchable, and Wearable Electronics
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Materials Science↗
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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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Advancing Photo(Electro)Chemical Water Splitting: The Promise of Atomically Dispersed Single‐, Dual‐, and Alloy‐Site Catalysts
Single-atom catalysts (SACs) have rapidly gained prominence as an emerging class of electrocatalysts for water splitting, owing to their uniform and precisely defined active sites. By maintaining uniform reaction pathways, SACs minimize the formation of unwanted byproducts, thus exhibiting extremely high selectivity and atomic efficiency. A key determinant of SAC performance lies in the interfacial interaction between the isolated metal atoms and the supporting material under strong metal–support coordination, which is vital for maintaining long-term activity. However, despite these benefits, reproducibly synthesizing SACs with high metal loadings while retaining uniform dispersion remains a significant challenge. To address the intrinsic challenges of SACs, recent research has expanded into dual-atom catalysts (DACs) and single-atom alloy catalysts (SAACs), providing synergistic active sites and combining the benefits of SACs with bimetallic systems. Furthermore, this review systematically explores the latest advancements in synthesis methods and innovations for SACs for electrochemical water splitting. Additionally, it examines the evolution of catalyst design, emphasizing the unique structural and electronic characteristics of single-site, dual-site, and alloyed SAC systems and highlighting their critical roles in accelerating water-splitting reaction kinetics as well as the prevailing challenges and outlining promising directions for advancing hydrogen production via water electrolysis.
08 HYDROGEN↗
Panchromatic All‐Polymer Photodetector with Tunable Polarization Sensitivity
Abstract In this report, a high‐performance all‐polymer organic photodetector that is sensitive to linearly polarized light throughout the visible spectrum is demonstrated. The active layer is a bulk heterojunction composed of an electron donor polymer PBnDT‐FTAZ and acceptor polymer P(NDI2OD‐T2) that have complementary spectral absorption resulting in efficient detection from 350 to 800 nm. The blend film exhibits good ductility with the ability to accommodate large strains of over 60% without fracture. This allows the film to undergo large uniaxial strain resulting in in‐plane alignment of both polymers making the film optically anisotropic and intrinsically polarization sensitive. The films are characterized by UV–vis spectroscopy and grazing incidence wide‐angle X‐ray scattering showing that both polymers have similar in‐plane backbone alignment and maintain packing order after being strained. The films are integrated into devices and characterized under linear polarized light. The strain‐oriented detectors have maximum photocurrent anisotropies of 1.4 under transverse polarized light while maintaining peak responsivities of 0.21 A W −1 and a 3 dB cutoff frequency of ≈1 kHz. The demonstrated performance is comparable to the current state of the art all‐polymer photodetectors with the added capability of polarization sensitivity enabling new application opportunities.
Sen, Pratik↗
Nonlocal Metasurfaces and Their High Q‐Factors in Fano Resonances
Herein nonlocal metasurfaces of parallel bars stitched to cubic rectangles containing structural and symmetry perturbations with a coupling of localized Mie resonance in meta‐atoms and Bragg modes in photonic crystals are reported. Two Fano resonances have been identified that maintain ultrahigh Q‐factors at incident angles of light up to 5°. Increasing the symmetry of the meta‐atoms results in Fano resonances with Q‐factors increased by a factor of 26, compared with the metasurfaces with a single bar stitched to a cubic rectangle at the incident angle of 5°. Due to nonlocal coupling of Bragg scattering and Mie resonance, the Q‐factor maintains almost a constant at 5° of incidence, while it varies with structural or symmetrical perturbations at 0°.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Cesium Lead Halide Perovskite Nanocrystals Assembled in Metal–Organic Frameworks for Stable Blue Light Emitting Diodes
All inorganic cesium lead trihalide nanocrystals are promising light emitters for bright light emitting diodes (LEDs). Here we demonstrate CsPb(BrCl) 1.5 nanocrystals in metal-organic frameworks (MOF) thin films to achieve bright and stable blue LEDs. The lead metal nodes in the MOF thin film react with Cs-halide salts, resulting in 10~20 nm nanocrystals. This is revealed by X-ray scattering and transmission electron microscopy. Employing the CsPbX 3 - MOF thin films as emission layers, bright deep blue and sky-blue LEDs are demonstrated that emit at 452 nm and 476 nm respectively. The maximum external quantum efficiencies of these devices are 0.72% for deep blue LEDs and 5.6% for sky blue LEDs. More importantly, the device can maintain 50% of its original electroluminescence (T 50 ) for 2.23 hours when driving at 4.2V. Detailed optical spectroscopy and time-of-flight secondary ion mass spectroscopy suggest that the ion migration can be suppressed that maintains the emission brightness and spectra. Our study provides a new route for fabricating stable blue light emitting diodes with all-inorganic perovskite nanocrystals.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Reconfigurable Magnetic Liquid Building Blocks for Constructing Artificial Spinal Column Tissues
All-liquid molding can be used to transform a liquid into free-form solid constructs, while maintaining internal fluidity. Traditional biological scaffolds, such as cured pre-gels, are normally processed in solid state, sacrificing flowability and permeability. However, it is essential to maintain the fluidity of the scaffold to truly mimic the complexity and heterogeneity of natural human tissues. Here, this work molds an aqueous biomaterial ink into liquid building blocks with rigid shapes while preserving internal fluidity. The molded ink blocks for bone-like vertebrae and cartilaginous-intervertebral-disc shapes, are magnetically manipulated to assemble into hierarchical structures as a scaffold for subsequent spinal column tissue growth. It is also possible to join separate ink blocks by interfacial coalescence, different from bridging solid blocks by interfacial fixation. Generally, aqueous biomaterial inks are molded into shapes with high fidelity by the interfacial jamming of alginate surfactants. The molded liquid blocks can be reconfigured using induced magnetic dipoles, that dictated the magnetic assembly behavior of liquid blocks. The implanted spinal column tissue exhibits a biocompatibility based on in vitro seeding and in vivo cultivating results, showing potential physiological function such as bending of the spinal column.
60 APPLIED LIFE SCIENCES↗
Durable Thin‐Film Porous Transport Electrodes for High Current Density PEM Water Electrolysis
Proton exchange membrane water electrolyzers rely on relatively expensive Ir-based catalysts for efficient and durable hydrogen production. To reduce system costs, Ir loadings can be reduced if performance and durability are maintained. Sputter deposition is a readily scalable method to synthesize uniform, low-loading catalyst layers with controlled composition. A catalyst applied directly to the porous transport layer can have advantages for performance, manufacturing simplicity, and catalyst recovery. Suitable porous transport layer porosity can minimize activity losses when reducing loadings. Here, methods are presented to deposit metallic Ir as well as amorphous and rutile Ir oxides. The activity and durability of these materials in the porous transport electrode architecture is evaluated. The metallic and amorphous forms have better initial activity, however, operation at 3 A cm −2 with 0.1 mg Ir cm −2 shows that only rutile IrO 2 maintains performance beyond 100 h with a 50 mV improvement after 700 h. A >10x reduced dissolution rate is shown for rutile IrO 2 . With a low-porosity transport layer and 0.4 mg Ir cm −2 , a steady-state voltage decay rate of 6 µV h −1 is achieved. The results demonstrate that sputter-deposited rutile IrO 2 porous transport electrodes with low Ir loading can be operated at high current density to reduce hydrogen production costs.
08 HYDROGEN↗
High-performance silicon anodes enabled by nonflammable localized high-concentration electrolytes
Silicon (Si) anode is regarded as one of the most promising alternatives to graphite for high energy density lithium ion batteries (LIBs), but their practical applications have been hindered by high volume change, limited cycle life and safety concerns. In this work we developed nonflammable localized high concentration electrolytes (LHCEs) for Si-based anodes. The LHCEs enabled the Si anodes with significantly enhanced electrochemical performances comparing to the conventional carbonate electrolytes with high content of fluoroethylene carbonate (FEC). The LHCE with only 1.2 wt% FEC can further improve the long-term cycling stability of Si-based anodes. When coupled with a LiNi0.3Mn0.3Co0.3O2 cathode, the full cells using this nonflammable LHCE could maintain >90% capacity after 600 cycles at C/2 rate, demonstrate excellent rate capability and cycling stability at elevated temperatures and high loadings. This work casts new insights in electrolyte development from the perspective of in-situ Si/electrolyte interphase protection for high energy density LIBs with Si anodes.
Silicon anode, electrolyte, nonflammable, localize↗
High Thermoelectric Performance in PbSe–NaSbSe 2 Alloys from Valence Band Convergence and Low Thermal Conductivity
PbSe is an attractive thermoelectric material due to its favorable electronic structure, high melting point, and lower cost compared to PbTe. Herein, the hitherto unexplored alloys of PbSe with NaSbSe 2 (NaPb m SbSe m+2 ) are described and the most promising p-type PbSe-based thermoelectrics are found among them. Surprisingly, it is observed that below 500 K, NaPb m SbSe m+2 exhibits unorthodox semiconducting-like electrical conductivity, despite possessing degenerate carrier densities of ≈10 20 cm -3 . Here, it is shown that the peculiar behavior derives from carrier scattering by the grain boundaries. It is further demonstrated that the high solubility of NaSbSe 2 in PbSe augments both the thermoelectric properties while maintaining a rock salt structure. Namely, density functional theory calculations and photoemission spectroscopy demonstrate that introduction of NaSbSe 2 lowers the energy separation between the L- and Σ-valence bands and enhances the power factors under 700 K. The crystallographic disorder of Na + , Pb 2+ , and Sb 3+ moreover provides exceptionally strong point defect phonon scattering yielding low lattice thermal conductivities of 1–0.55 W m -1 K -1 between 400 and 873 K without nanostructures. As a consequence, NaPb 10 SbSe 12 achieves maximum ZT ≈1.4 near 900 K when optimally doped. More importantly, NaPb 10 SbSe 12 maintains high ZT across a broad temperature range, giving an estimated record ZT avg of ≈0.64 between 400 and 873 K, a significant improvement over existing p-type PbSe thermoelectrics.
36 MATERIALS SCIENCE↗
A Low-Cost Durable Na-FeCl2 Battery with Ultrahigh Rate Capability
Na-based batteries have long been regarded as an inexpensive, sustainable candidate for large-scale stationary energy storage applications. Unfortunately, the market penetration of conventional Na-NiCl2 batteries is approaching its limit for several reasons, including limited rate capability and high Ni cost. Herein, a Na-FeCl2 battery operating at 190 °C is reported that allows a capacity output of 116 mAh g-1 at an extremely high current density of 33.3 mA cm-2 (˜0.6C). The superior rate performance is rooted in the intrinsically fast kinetics of the Fe/Fe2+ redox reaction. Furthermore, it is demonstrated that a small amount of Ni additive (10 mol%) effectively mitigates capacity fading of the Fe/NaCl cathode caused by Fe particle pulverization during long-term cycling. The modified Fe/Ni cathode exhibits excellent cycling stability, maintaining a discharge energy density of over 295 Wh kg-1 for 200 cycles at 10 mA cm-2 (˜C/5).
Zhan, Xiaowen↗
A High-Performance Na-Al Battery Based on Reversible NaAlCl4 Catholyte
This work demonstrates a high-capacity and safe Na-Al battery pairing sodium metal anode and reversible NaAlCl4 catholyte for grid scale energy storage applications. The energy-rich sodium anode allows the full play of the aluminum cathode, resulting in a full-cell capacity of 308 mAh/g at a discharge voltage of 1.6 V. Benefiting from the use of ??-alumina solid electrolyte (BASE), molten sodium anode and reversible Al deposition/stripping from NaAlCl4 catholyte, the battery presents a stable Coulombic efficiency of 100% and energy efficiency of ~95%. At a rate of C/3 (6.77 mA/cm2), the cell maintains 282 mAh/g (447 Wh/kg) after 200 cycles with an excellent capacity retention of 97.6%. Moreover, we elucidate pathways to build sodium-anode-free cells from the discharged state under dry air, which further extends the feasibility of this battery for stationary storage applications. These findings are expected to provide a new platform for the development of practical Al batteries.
Zhan, Xiaowen↗
In–Depth Analysis of the Degradation Mechanisms of High–Nickel, Low/No–Cobalt Layered Oxide Cathodes for Lithium–Ion Batteries
A rational compositional design of high-nickel, cobalt-free layered oxide materials for high-energy and low-cost lithium-ion batteries would be expected to further propel the widespread adoption of electric vehicles (EVs), yet a composition with satisfactory electrochemical properties has yet to emerge. The previous work has demonstrated a promising LiNi 0.883 Mn 0.056 Al 0.061 O 2 (NMA-89) composition that outperformed high-nickel, cobalt-containing analogs in cycling stability and maintained a comparable rate performance and thermal stability. Herein, the capacity fading mechanism of NMA-89 in a pouch full cell with a 4.2 V cutoff is compared to that of its cobalt-containing analogs. The results reveal that particle cracking in LiNi 0.89 Mn 0.055 Co 0.055 O 2 (NMC-89) and LiNi 0.883 Co 0.053 Al 0.064 O 2 (NCA-89) leads to a loss of active material and an increase in surface area, thereby exacerbating structural and surface instabilities, accelerating impedance and polarization growth, and ultimately reducing their capacity retentions. LiNi 0.89 Mn 0.044 Co 0.042 Al 0.013 Mg 0.011 O 2 (NMCAM-89) and NMA-89 experience subdued surface reactions and maintain spherical particle structures, both of which are conducive to their capacity retentions during long-term cycling. Furthermore, this investigation offers insights into how specific transition-metal ions dictate the electrochemical stability of high-Ni layered oxide cathode materials, highlights the benefit of Mn-Al combination in NMA-89, and presents potential strategies to further enhance the performance of this novel class of cathode materials.
degradation mechanisms↗
Transparent, High‐Charge Capacity Metal Mesh Electrode for Reversible Metal Electrodeposition Dynamic Windows with Dark‐State Transmission <0.1%
Abstract Dynamic windows allow user control over light and heat flow to save energy and maximize comfort. Reversible metal electrodeposition (RME) dynamic windows can uniquely tint to a color‐neutral privacy state (0.1% visible light transmission). The design parameters of transparent metal mesh counter electrodes for high‐contrast RME dynamic windows: high transparency, charge capacity and surface area with low haze, sheet resistance and cost are discussed, concluding that woven metal meshes meet these design parameters. Electroplated current is measured on an indium tin oxide electrode and two meshes with different wire spacings, showing the meshes’ cylindrical geometry enable them to draw more current per square area. The mesh material composition is analyzed to ensure cycling durability in a CuBi electrolyte by developing a transparent mesh with an inert core (stainless steel, SS), a thin Au coating, and a high charge‐capacity (1.5 C cm −2 ) CuBi outer coating. The study demonstrates that the films maintain a consistent Cu:Bi ratio and optical properties after 250 privacy cycles or 1500 cycles to 10% transmission, showing that the Cu and Bi coating is effective in keeping the films from becoming Cu rich with cycling. Finally, a 100 cm 2 device with excellent uniformity and color neutrality is demonstrated.
Yeang, Andrew L.↗
A machine learning approach for clinker quality prediction and nonlinear model predictive control design for a rotary cement kiln
Abstract Cement manufacturing is energy‐intensive (5Gj/t) and comprises a significant portion of the energy footprint of concrete systems. Incorporating modern monitoring, simulation and control systems will allow lower energy use, lower environmental impact, and lower costs of this widely used construction material. One of the goals of the CESMII roadmap project on the Smart Manufacturing of Cement included developing an analytical process model for clinker quality that includes the chemistry of the kiln feed and accounts for critical process variables. This predictive model will be used in nonlinear model predictive control system designed to significantly reduce process energy use while maintaining or improving product quality. In the cement manufacturing plant used in this study, the kiln feed (meal) is tested every 12 h and used to estimate the mineral composition of the cement kiln output (clinker) using the stoichiometry‐based Bogue's model and the expertise of the plant operators. During kiln operation, kiln output (clinker) is sampled and tested every 2 h to measure its chemical and mineral composition. The predicted and measured values of the clinker composition are used by the plant operators to adjust the kiln input stream and the production process characteristics to maintain stable operation and uniform product quality. However, the time delay between prediction and testing, along with inaccuracies inherent in the Bogue's model have made any process changes designed to minimize energy use problematic, especially in‐light of potential clinker quality issues that process changes often pose. A new analytical model that integrates quality information and process operation information has been developed from data collected from 2 years of production from an operating cement facility. To make the model fuel‐type‐independent, consumed heat energy was computed in the model instead of fuel type and amount. A Feedforward Network was trained and tailored from collected data. Many data‐based simulations were conducted to quantitatively evaluate the proposed model and the 5‐fold cross‐validation procedure was used to test the models. The resulting predictive model was shown to have a low root mean square error (MSE) with respect to the estimated clinker mineral composition compared to that using the industry standard “Bogue’ model”. The end goal of this work was to develop a single machine learning tool that allows the use of quality control data and process control variables to improve energy efficiency of the process in a continuous fashion. The proposed nonlinear model predictive control system (NMPC) can generate predicted kiln production characteristics based on manipulated variables in manner that accurately follows the target product quality values. Simulation results also show that the proposed model produced accurate predictions of kiln outputs that fell within the required constraints, while manipulating control variables within typical operational ranges.
Ali, Asem M.↗
Ending Aging in Super Glassy Polymer Membranes
Aging in super glassy polymers such as poly(trimethylsilylpropyne) (PTMSP), poly(4-methyl-2-pentyne) (PMP), and polymers with intrinsic microporosity (PIM-1) reduces gas permeabilities and limits their application as gas-separation membranes. While super glassy polymers are initially very porous, and ultra-permeable, they quickly pack into a denser phase becoming less porous and permeable. This age-old problem has been solved by adding an ultraporous additive that maintains the low density, porous, initial stage of super glassy polymers through absorbing a portion of the polymer chains within its pores thereby holding the chains in their open position. This result is the first time that aging in super glassy polymers is inhibited whilst maintaining enhanced CO2 permeability for one year and improving CO2/N-2 selectivity. This approach could allow super glassy polymers to be revisited for commercial application in gas separations.
Lau, CH↗
Direct Catalytic Conversion of Ethanol to C[subscript 5+] Ketones: Role of Pd-Zn Alloy on Catalytic Activity and Stability
Abstract not provided
Subramaniam, Senthil↗
Simulating and evaluating best management practices for integrated landscape management scenarios in biofuel feedstock production: Evaluating Best Management Practices for Biofuel Feedstock Production
Sound crop and land management strategies can maintain land productivity and improve the environmental sustainability of agricultural crop and feedstock production. This study evaluates the improvement of water sustainability through an integrated landscaping management strategy, where landscaping design, land management operations, crop systems, and agricultural best management practices (BMPs) play equal roles. The strategy was applied to the watershed of the South Fork Iowa River in Iowa, with a focus on implementing riparian buffers and converting low productivity land to provide cellulosic biomass while benefiting soil and water quality. The Soil and Water Assessment Tool (SWAT) was employed to simulate the impact of integrated landscape design on nutrients, suspended sediments, and flow on the watershed and subbasin scales. First, the study evaluated the representation of buffer strip as a vegetative barrier and as a riparian buffer using trapping efficiency and area ratio methods in SWAT. For the riparian buffer, the area ratio method tends to be more conservative, especially in nitrate loadings, while the trapping efficiency method generates more optimistic results. The differences between the two methods increase with buffer width. The two methods may not be comparable for the field-scale vegetative barrier simulation because of limitations in model spatial resolution. Landscape scenarios were developed to quantify water quality under (1) current land use, (2) partial land conversion to switchgrass, and (3) riparian buffer implementation. Results show that when low productivity land (15.2% of total watershed land area) is converted to grow switchgrass, suspended sediment, total nitrogen, total phosphorus, and nitrate loadings are reduced by 69.3%, 55.5%, 46.1%, and 13.4%, respectively, in the watershed surface streams. The reduction was less extensive when riparian buffer strips (30 m or 50 m) were applied to the stream network at 1.4% of total land area in the watershed. At the subbasin level, the degree of nutrient and suspended sediment reduction varies extensively, ranging from a few percent up to 55%. Results indicate that effective landscape design on current agricultural land can potentially bring marked improvements in water quality and soil erosion control while producing food and fuel feedstock in the South Fork Iowa River watershed. The concept can be integrated with other watershed management programs to improve sustainability of land, water, and the ecosystem.
bioenergy production↗
Material selection and manufacturing for high‐temperature heat exchangers: Review of state‐of‐the‐art development, opportunities, and challenges
Abstract Many energy systems demand heat transfer at high temperatures to keep up with high demand for power, so high‐temperature material that can perform and last under these harsh conditions is needed for heat exchangers. The engineering requirements for these high‐temperature heat exchanger material call for high thermal conductivity, high resistance to fracture, high resistance to creep deformation, environmental stability in environments associated with the application, and high modulus of elasticity while maintaining low cost to make and maintain. Naturally, ceramics are a good solution for this endeavor. In the past, high‐temperature heat exchangers made from ceramics have been used. We provide examples of ceramics in relevant heat exchange applications and provide motivation where additive manufacturing (AM) can improve efficiency. AM for the relevant material is under development, and we provide insight on the AM of ceramic materials and examples of AM heat exchangers keeping cost in mind. The motivation of the review paper is to provide a framework for material and manufacturing selection for high‐temperature heat exchangers for AM to keep up with the demand for better efficiency, better material, better manufacturing, and cost moving forward with AM technology in high‐temperature ceramic heat exchangers.
36 MATERIALS SCIENCE↗