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DOE OSTI2019

Mass Transfer and Reaction Kinetic Enhanced Electrode for High‐Performance Aqueous Flow Batteries

Abstract A scalable and efficient process to modify electrodes with enhanced mass transfer and reaction kinetics is critical for redox flow batteries (RFBs). For the first time, this work introduces electrochemical exfoliation as a surface modification method of graphite felt (GF) to enhance the mass transfer and reaction kinetics in RFBs. Anion intercalation and subsequent gas evolutions at room temperature for one minute expand the graphite layers that increase the electrode surface area. Meanwhile, sufficient oxygen functional groups are introduced to the electrode, resulting in enhanced reaction kinetics and improved hydrophilicity. Further, spin‐polarized density functional theory is employed to reveal the role of oxygen functional groups in accelerating the vanadium redox reaction. Benefitting from sufficient oxygen groups, larger surface area, and superior wettability, the as‐prepared exfoliated GF (E‐GF) shows exceptional electrocatalytic activity with minimized overpotential, higher volumetric capacity, and improved energy efficiency. The redox flow battery assembled with the E‐GF electrode delivers voltage and energy efficiencies of 89.72% and 86.41% at the current density of 100 mA cm −2 , respectively. Remarkably, compared to the traditional GF treatment method, the elimination of the high temperature and long‐time treatment processes make this approach much more energy and time efficient, scalable, and affordable for large‐scale manufacturing.

Mukhopadhyay, Alolika↗

DOE OSTI2020

Chitin- and cellulose-based sustainable barrier materials: a review

Abstract The accumulation of synthetic plastics used in packaging applications in landfills and the environment is a serious problem. This challenge is driving research efforts to develop biodegradable, compostable, or recyclable barrier materials derived from renewable sources. Cellulose, chitin/chitosan, and their combinations are versatile biobased packaging materials because of their diverse biological properties (biocompatibility, biodegradability, antimicrobial properties, antioxidant activity, non-toxicity, and less immunogenic compared to protein), superior physical properties (high surface area, good barrier properties, and mechanical properties), and they can be assembled into different forms and shapes (powders, fibers, films, beads, sponges, gels, and solutions). They can be either assembled into packaging films or used as fillers to improve the properties of other biobased polymers. Methods such as preparation of composites, multilayer coating, and alignment control are used to further improve their barrier, mechanical properties, and ameliorate their moisture sensitivity. With the growing application of cellulose and chitin-based packaging materials, their biodegradability and recyclability are also discussed in this review paper. The future trends of these biobased materials in packaging applications and the possibility of gradually replacing petroleum-based plastics are analyzed in the “Conclusions” section.

36 MATERIALS SCIENCE↗

DOE OSTI2017

La and Al co-doped CaMnO 3 perovskite oxides: From interplay of surface properties to anion exchange membrane fuel cell performance

This work reports the first account of perovskite oxide and carbon composite oxygen reduction reaction (ORR) catalysts integrated into anion exchange membrane fuel cells (AEMFCs). Perovskite oxides with a theoretical stoichiometry of Ca 0.9 La 0.1 Al 0.1 Mn 0.9 O 3-δ are synthesized by an aerogel method and calcined at various temperatures, resulting in a set of materials with varied surface chemistry and surface area. Material composition is evaluated by X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The perovskite oxide calcined at 800 degrees C shows the importance of balance between surface area, purity of the perovskite phase, and surface composition, resulting in the highest ORR mass activity when evaluated in rotating disk electrodes. Integration of this catalyst into AEMFCs reveals that the best AEMFC performance is obtained when using composites with 30:70 perovskite oxide:carbon composition. Doubling the loading leads to an increase in the power density from 30 to 76 mW cm -2 . The AEMFC prepared with a composite based on perovskite oxide and N-carbon achieves a power density of 44 mW cm -2 , demonstrating an ~50% increase when compared to the highest performing composite with undoped carbon at the same loading.

36 MATERIALS SCIENCE↗

DOE OSTI2014

Ultrasonic spray pyrolysis growth of ZnO and ZnO:Al nanostructured films: Application to photocatalysis

Highlights: • Al–ZnO thin films and nanostructures were obtained by ultrasonic spray pyrolysis. • The texture and morphology of the samples depend on the deposition parameters. • The photocatalytic degradation of stearic acid was studied upon UV-A irradiation. - Abstract: Pure and Al-doped ZnO (Al = 1, 3, 5%) nanostructured thin films were grown at 400 °C on glass substrates by ultrasonic spray pyrolysis, a simple, environmental-friendly and inexpensive method, using aqueous solutions as precursors. The structural and morphological characteristics of the samples depend drastically on deposition parameters; ZnO nanostructured films, nanopetals and nanorods were systematically obtained by simply varying the precursor solution and/or the spraying time. Transmittance measurements have shown that all samples are transparent in the visible wavelength region. Finally, the photocatalytic properties of the samples were investigated against the degradation of stearic acid under UV-A light illumination (365 nm); both pure and Al-doped ZnO nanostructured thin films show good photocatalytic activity regarding the degradation of stearic acid, due to their good crystallinity and large surface area.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Enhanced CO 2 Adsorption Capacity in Highly Porous Carbon Materials Derived from Melamine-Formaldehyde Resin

Here, the present study explores the synthesis of N-doped carbon materials with large surface porosity using commercial melamine-formaldehyde resin as the precursor and KOH as the activator. The resin was carbonized first and then activated by KOH with varying KOH amount and activation temperature. Notably, the as-obtained sorbents display advanced porosity with the highest surface area and pore volume of 1591 m 2 /g and 0.74 cm 3 /g, respectively, along with high N content ranging from 6.43 to 18.34 wt %. Remarkably, maximum CO 2 capture amounts of 5.42 and 3.52 mmol/g were accomplished at 0 and 25 degrees C, 1 bar for as-synthesized carbons. Systematic studies point out that narrow microporosity is the major factor determining the CO 2 uptake of these carbons under ambient pressure. Furthermore, these sorbents display notable CO 2 selectivity, rapid adsorption kinetics, moderate heat of adsorption, substantial dynamic CO 2 capture capacity, and stable recyclability. These results underscore the potential of melamine-formaldehyde resin-derived N-doped porous carbon as an efficient and versatile adsorbent for CO 2 capture.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2019

Using a 3D Porous Flow-Through Electrode Geometry for High-Rate Electrochemical Reduction of CO 2 to CO in Ionic Liquid

Three-dimensional porous flow-through electrodes promise the realization of higher current densities in the electrochemical carbon dioxide reduction reaction (CO 2 RR) by overcoming mass-transport limitations associated with the diffusion of dissolved CO 2 in the bulk electrolyte. Using an ionic-liquid-based electrolyte, [EMIM]BF 4 , offers the additional benefit of higher CO 2 solubility compared to water-based electrolytes. Here, we quantitatively evaluated the effects of flow-driven reactant transport on electrode activity and selectivity for the electrochemical CO 2 RR in [EMIM]BF4. High-surface-area porous flow-through electrodes were fabricated by wet-chemical deposition of Ag nanoflowers on commercial macroporous Al foams. At the highest electrolyte flow-through rate of 100 mL min –1 , we observed a 70-fold increase in partial CO current density, and a 7-fold increase in the Faradaic efficiency toward CO, from 10% without flow to 75% with flow. At the same time, the selectivity changed from oxalate as the main product without flow to CO in the electrolyte flow-through configuration. These results demonstrate that the flow-through approach provides a promising path forward to control selectivity and to overcome mass-transport limitations of the electrochemical CO 2 RR.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

Architecting the Third Dimension of Electrochemical Energy Storage

Three-dimensional (3D) architectural design has emerged as a powerful strategy to push electrochemical energy storage (EES) devices beyond the intrinsic limitations of conventional two-dimensional (2D) electrodes. While planar architectures enable high packing density and mature manufacturing, they suffer from limited ion transport and low active-material loading. In contrast, 3D architectures introduce low-tortuosity networks and high surface area that enhance charge and mass transport while supporting thick, high mass-loading electrodes. However, their practicality remains hindered by challenges in volumetric density, mechanical stability, and large-scale manufacturability. Here, this Perspective examines the key evaluation and design principles that govern 3D device performance. We discuss the fundamental trade-offs between porosity, volumetric density, and mechanical stability that shape 3D design and highlight emerging strategies for integrating materials engineering, structural optimization, device integration, computational modeling, and scalable manufacturing. By aligning structural functionality with manufacturability, 3D architectures can evolve from laboratory prototypes to commercially viable energy storage systems.

25 ENERGY STORAGE↗

DOE OSTI2019

Pt–Ni Seed-Core-Frame Hierarchical Nanostructures and Their Conversion to Nanoframes for Enhanced Methanol Electro-Oxidation

Pt–Ni nanostructures are a class of important electrocatalysts for polymer electrolyte membrane fuel cells. This work reports a systematic study on the reaction mechanism of the formation of Pt–Ni seed-core-frame nanostructures via the seeded co-reduction method involving the Pt seeds and selective co-reduced deposition of Pt and Ni. The resultant structure consists of a branched Pt ultrafine seed coated with a pure Ni as rhombic dodecahedral core and selective deposition of Pt on the edges of the cores. Both the type of Pt precursor and the precursor ratio of Pt/Ni are critical factors to form the resulting shape of the seeds and eventually the morphology of the nanostructures. These complex hierarchical structures can be further graved into hollow Pt–Ni alloy nanoframes using acetic acid etching method. The larger surface area and higher number of low coordinate sites of the nanoframes facilitate the electrocatalytic activity and stability of Pt–Ni alloy for methanol oxidation as compared to their solid counterparts. This study elucidates the structural and compositional evolution of the complex nanoarchitectures and their effects on the electrocatalytic properties of the nanostructures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

NASA NTRS1995

Full resolution hologram-like autostereoscopic display

Under this program, Dimension Technologies Inc. (DTI) developed a prototype display that uses a proprietary illumination technique to create autostereoscopic hologram-like full resolution images on an LCD operating at 180 fps. The resulting 3D image possesses a resolution equal to that of the LCD along with properties normally associated with holograms, including change of perspective with observer position and lack of viewing position restrictions. Furthermore, this autostereoscopic technique eliminates the need to wear special glasses to achieve the parallax effect. Under the program a prototype display was developed which demonstrates the hologram-like full resolution concept. To implement such a system, DTI explored various concept designs and enabling technologies required to support those designs. Specifically required were: a parallax illumination system with sufficient brightness and control; an LCD with rapid address and pixel response; and an interface to an image generation system for creation of computer graphics. Of the possible parallax illumination system designs, we chose a design which utilizes an array of fluorescent lamps. This system creates six sets of illumination areas to be imaged behind an LCD. This controlled illumination array is interfaced to a lenticular lens assembly which images the light segments into thin vertical light lines to achieve the parallax effect. This light line formation is the foundation of DTI's autostereoscopic technique. The David Sarnoff Research Center (Sarnoff) was subcontracted to develop an LCD that would operate with a fast scan rate and pixel response. Sarnoff chose a surface mode cell technique and produced the world's first large area pi-cell active matrix TFT LCD. The device provided adequate performance to evaluate five different perspective stereo viewing zones. A Silicon Graphics' Iris Indigo system was used for image generation which allowed for static and dynamic multiple perspective image rendering. During the development of the prototype display, we identified many critical issues associated with implementing such a technology. Testing and evaluation enabled us to prove that this illumination technique provides autostereoscopic 3D multi perspective images with a wide range of view, smooth transition, and flickerless operation given suitable enabling technologies.

Eichenlaub, Jesse B.↗

NASA NTRS1996

The Pathfinder Microrover

An exciting scientific component of the Pathfinder mission is the rover, which will act as a mini-field geologist by providing us with access to samples for chemical analyses and close-up images of the Martian surface, performing active experiments to modify the surface and study the results, and exploring the landing site area.

Mars Mars Pathfinder rover microrover imager for p↗

NASA NTRS2019

Statistical Analysis of Aquarius Radiometer Radio Frequency Interference (RFI) and Implications on RFI Detection and Mitigation

The Aquarius/SAC-D mission operated between August 2011 and June 2015 with the main goal of providing global estimates of sea surface salinity (SSS). It comprised both active and passive microwave sensors operating at L-band to observe the same surface area almost simultaneously. Measurements from both instruments underwent subsequent filtering to mitigate the effect of Radio Frequency Interference (RFI). This report describes the analysis of statistics of RFI in samples acquired by the Aquarius radiometers, and its results could be used to improve the performance of the interference detection algorithm.

De Matthaeis, Paolo↗

DOE OSTI2022

Electrocatalyst comprising a crumpled transition metal dichalcogenide support loaded with monodispersed metal nanoparticles

An electrocatalyst comprises a crumpled transition metal dichalcogenide support loaded with catalytic metal nanoparticles through spontaneous reduction reactions. The support can be prepared by hydrothermal conversion of 2D nanosheets to 3D hierarchically crumpled sheets. As an example, using crumpled MoS 2 as a support, highly tunable Ru loadings were obtained using the electrostatic interaction between MoS 2 and RuCl 3 in solution. Control over Ru loading was leveraged to produce Ru—MoS 2 electrocatalysts that demonstrate different nitrogen reduction reaction activities, and which show varying resistance to electrochemical sintering and deactivation. Further, these high surface area materials can be utilized for many applications, including electrocatalysts, supercapacitors, and batteries.

Percival, Stephen↗

DOE OSTI2021

Precise Identification and Characterization of Catalytically Active Sites on the Surface of γ‐Alumina**

Abstract γ‐alumina is one of the oldest and most important commercial catalytic materials with high surface area and stability. These attributes enabled its use as the first commercial large‐scale heterogeneous catalyst for ethanol dehydration. Despite progress in materials characterization the nature of the specific sites on the surface of γ‐alumina that are responsible for its unique catalytic properties has remained obscure and controversial. By using combined infrared spectroscopy, electron microscopy and solid‐state nuclear magnetic resonance measurements we identify the octahedral, amphoteric (O) 5 Al(VI)‐OH sites on the (100) segments of massively restructured (110) facets on typical rhombus‐platelet γ‐alumina as well as the (100) segments of irrational surfaces (invariably always present in all γ‐alumina samples) responsible for its unique catalytic activity. Such (O) 5 Al(VI)‐OH sites are also present on the macroscopically defined (100) facets of γ‐alumina with elongated/rod‐like geometry. The mechanism by which these sites lose ‐OH groups upon thermal dehydroxylation resulting in coordinatively unsaturated penta‐coordinate Al +3 O 5 sites is clarified. These coordinatively unsaturated penta‐coordinate Al sites produce well‐defined thermally stable Al‐carbonyl complexes. Our findings contribute to the understanding of the nature of coordinatively unsaturated Al sites on the surface of γ‐alumina and their role as catalytically active sites.

Khivantsev, Konstantin↗

DOE OSTI2016

Regional quantitative play fairway analysis: methodology global examples and application for the East African Rift system

Most volcanic arcs and active rifts around the world host producing geothermal systems. Many undiscovered and/or undeveloped systems remain in each of these areas, including magmatic-heated systems, amagmatic extension-related systems, and blind resources lacking active surface manifestations in both types of settings. However, not all volcanic centers or extensional terranes have the same geothermal potential. For example, even when high heat flow is present, permeability is commonly a limiting factor to resource development. A tool recently adapted for the geothermal industry is play fairway analysis, which calculates the regional probability of power-capable resources based on the spatial coincidence of key geologic conditions. In a geothermal setting, these key geologic conditions are heat, permeability, and fluids. Higher enthalpy systems also benefit from suitable cap rock. These parameters can be assessed through multiple geologic, geochemical, and geophysical data sets and integrated quantitatively to produce a single geothermal play fairway map. Potential input data sets include but are not limited to: 1) tectonic setting; 2) structural setting; 3) faults attributed by recency of rupture and slip rate; 3) geodetic crustal stain models; 5) gravity; 6) earthquake distribution; 7) thermal models; 8) geochemistry from springs, wells, and fumaroles; 9) temperature from springs, wells, and fumaroles; 10) fumarole size and type; and 11) age of volcanism. Recent play fairway studies have been completed for volcanic arcs and the dominantly amagmatic, extensional Great Basin region, USA, but have yet to be applied to the East African Rift System (EARS). Previous estimates of total geothermal resource capacity in the EARS is ~20 GWe, but only three areas are currently in production as of 2015: Olkaria and Eburru in Kenya, and Aluto-Langano in Ethiopia for a total installed capacity of <0.7 GWe. Many more volcanic centers host potential resources. In addition, amagmatic and/or blind systems also have potential in the EARS. Play fairway analysis can highlight regions most prospective for geothermal resource development, help identify locations prospective for undiscovered resources, prioritize overall exploration and development efforts, and refine estimates for total undeveloped resource potential.

15 GEOTHERMAL ENERGY↗

DOE OSTI2020

Deep Understanding of Strong Metal Interface Confinement: A Journey of Pd/FeO x Catalysts

Tuning the atomic interface configuration of noble metals (NMs) and transition-metal oxides is an effective straightforward yet challenging strategy to modulate the activity and stability of heterogeneous catalysts. Herein, Pd supported on mesoporous Fe 2 O 3 with a high specific surface area was rationally designed and chosen to construct the Pd/iron oxide interface. As a versatile model, the physicochemical environments of Pd nanoparticles (NPs) could be precisely controlled by taming the reduction temperature. The experimental and density functional theory calculation results unveiled that the catalyst in the support–metal interface confinement (SMIC) state showed significantly enhanced catalytic activity and sintering resistance for CO oxidation. The constructed Fe sites at the interfaces between FeO x overlayers and Pd NPs not only provided additional coordinative unsaturated ferrous sites for the adsorption and activation of O 2 , thereby facilitating the activation efficiency of O 2 , but also impressively changed the reaction pathway of CO oxidation. As a result, the catalyst followed the Pd/Fe dual-site mechanism instead of the classical Mars–van Krevelen mechanism. For the catalyst in the strong metal–support interaction (SMSI) state, its catalytic activity was seriously suppressed because of the excessive encapsulation of the active Pd sites by FeO x overlayers. Thus, the present study therefore provides detailed insights into the SMIC and SMSI in ferric oxide-supported Pd catalysts, which could guide the preparation of highly efficient supported catalysts for practical applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1984

Rotational modulation of the chromospheric activity in Chi(1) Orionis (G0 V)

The age and rotation period of the solar type star Chi(1) Ori recommend it for a rotational modulation study of its strong UV emission lines. IUE observations have accordingly been made at four different phases during each of three separate rotation cycles, over a time span of 325 days. C IV, He II, and Mg II observations are consistent with a uniform spatial distribution and brightness for the Mg II emission network, and a more complex distribution of the regions producing the UV transmission region emission. Alternatively, if the area coverage of the chromospheric and transition region emission is nearly identical, the surface brightness contrast between stellar active regions and normal ones must increase by almost an order of magnitude in the higher temperature lines.

Simon, T.↗

DOE OSTI2018

Supercapacitance and oxygen reduction characteristics of sulfur self-doped micro/mesoporous bio-carbon derived from lignin

The growing global concerns about the increased fossil fuel consumption and related environmental issues have motived scientists to find new, green and sustainable energy resources and technologies. In this work, byproduct lignin biomass was successfully converted into sulfur self-doped carbon via in-situ hydrothermal carbonization followed by thermal annealing. The sulfur surface content in the as-prepared porous carbon is up to 3.2 wt % as indicated by the XPS measurements. Beyond the traditional synthesis methods which employ KOH or ZnCl 2 treatment to activate the carbon surface, the developed synthesis strategy doesn't include such separate activation step. Activation of the as-prepared porous carbons has been conducted in-situ via a calcium ions during the synthesis process. The resulting materials displayed high BET surface areas up to 660 m 2 g -1 along with micro/meso porosity and graphitic/amorphous carbon structure. The as-prepared sulfur self-doped electrode materials displayed high electrochemical activity for supercapacitor applications. The sulfur-doped carbon SC-850 electrode exhibited capacitance of 225 F/g at a current density of 0.5 A/g, and high durability where the electrode capacitance did not change over 10,000 cycles at harsh conditions. Additionally, the as-prepared sulfur-doped carbons are promising catalysts for oxygen reduction reaction with 3.4 electrons transferred per molecule at 0.8 V, which approaches the optimum 4-electron pathway.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2014

Solvent polarity and nanoscale morphology in bulk heterojunction organic solar cells: A case study

Organic bulk heterojunction solar cells were fabricated under identical experimental conditions, except by varying the solvent polarity used for spin coating the active layer components and their performance was evaluated systematically. Results showed that presence of nitrobenzene-chlorobenzene composition governs the morphology of active layer formed, which is due to the tuning of solvent polarity as well as the resulting solubility of the P3HT:PCBM blend. Trace amount of nitrobenzene favoured the formation of better organised P3HT domains, as evident from conductive AFM, tapping mode AFM and surface, and cross-sectional SEM analysis. The higher interfacial surface area thus generated produced cells with high efficiency. But, an increase in the nitrobenzene composition leads to a decrease in cell performance, which is due to the formation of an active layer with larger size polymer domain networks with poor charge separation possibility.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗