Search NASA⌕ Search

SEARCH · Search NASA

Results for “Organic electrode materials”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Characterizing Sustained Solar-to-Hydrogen Electrocatalysis at Low Cell Potentials Enabled by Crude Glycerol Oxidation

Unassisted solar-driven water electrolysis as a sustainable source for H 2 is limited by the high overpotential necessary to drive the oxygen evolution reaction (OER). Crude glycerol is an extremely alkaline byproduct of biodiesel synthesis that can be valorized or refined to produce more desirable chemicals. Glycerol can also be directly oxidized on an anode, replacing water oxidation, to reduce the applied cell potential requirements of electrolytic H 2 production or CO 2 reduction. An advantage of oxidizing glycerol in its crude form is the opportunity to valorize it without initial refinement. We describe an approach to replace the OER half-reaction with the sacrificial crude glycerol electrooxidation on a layered Au–Pt–Bi electrocatalyst on a Ni substrate. Compared to compositions with fewer components, the AuPtBi–Ni electrocatalyst improved the duration of performance and reduced the overall cell potential for glycerol electrooxidation in the extreme alkaline solutions representative of crude glycerol. These enhancements facilitated extended, unassisted hydrogen evolution from crude glycerol electrolysis, even under the power of a single-junction silicon solar cell at less than 1 sun illumination. We characterized the oxidation products of crude glycerol electrolysis and the subsequent products formed spontaneously in the electrolyte in the highly alkaline solution. This analysis helps to both identify the stoichiometric limits of glycerol oxidation at the low cell potentials of interest here and to understand the chemical control imparted by electrocatalysis on the ultimate compounds formed in the crude solution. Furthermore, the results for the AuPtBi electrocatalyst show that incorporating crude glycerol oxidation into integrated electrochemical systems can simultaneously simplify their design and significantly improve solar-to-hydrogen rates.

08 HYDROGEN↗
DOE OSTI2022

Analyzing Production Rate and Carbon Utilization Trade-offs in CO 2 RR Electrolyzers

Carbon utilization is a crucially important performance characteristic of CO 2 electrolyzers; however, applications of simple and accurate descriptive models to experimental data on this topic are currently lacking. Here, we apply a simple analytical reactor model to parameterize single-pass conversion as a function of feed-gas flow rate and show that it captures a wide body of experimental data in the literature exceptionally well. In doing so, we demonstrate that this simple conceptual approach can characterize progress and capture recent innovations in reactor design. To validate the extracted parameters, we employ a well-established comprehensive model to confirm that the results agree with physical expectations. Lastly, we explore the implications of the descriptive model by examining the inherent trade-off between single-pass conversion efficiency and reactor productivity. Understanding such trade-offs is crucially important for advancing this electrolyzer technology toward commercial applications.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Development of High-Capacity Cathodes and Robust Solid Electrolytes

In Phase 1, the University of Texas at Austin explored many methods of cathode design, synthesis, and modification, while also developing an understanding of the relationships among the cathode, anode, and electrolyte. Some of the major accomplishments are highlighted in this report.

25 ENERGY STORAGE↗
DOE OSTI2021

Non-Solvent Induced Phase Separation Enables Designer Redox Flow Battery Electrodes

Porous carbonaceous electrodes are performance-defining components in redox flow batteries (RFBs), where their properties impact the efficiency, cost, and durability of the system. The overarching challenge is to simultaneously fulfill multiple seemingly contradictory requirements—i.e., high surface area, low pressure drop, and facile mass transport—without sacrificing scalability or manufacturability. Here, non-solvent induced phase separation (NIPS) is proposed as a versatile method to synthesize tunable porous structures suitable for use as RFB electrodes. The variation of the relative concentration of scaffold-forming polyacrylonitrile to pore-forming poly(vinylpyrrolidone) is demonstrated to result in electrodes with distinct microstructure and porosity. Tomographic microscopy, porosimetry, and spectroscopy are used to characterize the 3D structure and surface chemistry. Flow cell studies with two common redox species (i.e., all-vanadium and Fe2+/3+) reveal that the novel electrodes can outperform traditional carbon fiber electrodes. It is posited that the bimodal porous structure, with interconnected large (>50 µm) macrovoids in the through-plane direction and smaller (<5 µm) pores throughout, provides a favorable balance between offsetting traits. Although nascent, the NIPS synthesis approach has the potential to serve as a technology platform for the development of porous electrodes specifically designed to enable electrochemical flow technologies.

36 MATERIALS SCIENCE↗
DOE OSTI2022

An SECM-Based Spot Analysis for Redoxmer-Electrode Kinetics: Identifying Redox Asymmetries on Model Graphitic Carbon Interfaces

The fundamental process in non-aqueous redox flow battery (NRFB) operation revolves around electron transfer (ET) between a current collector electrode and redox-active organic molecules (redoxmers) in solution. Here, we present an approach utilizing scanning electrochemical microscopy (SECM) to evaluate interfacial ET kinetics between redoxmers and various electrode materials of interest at desired locations. This spot-analysis method relies on the measurement of heterogeneous electron transfer rate constants (k f or k b ) as a function of applied potential (E-E 0 '). As demonstrated by COMSOL simulations, this method enables the quantification of Butler-Volmer kinetic parameters, the standard heterogeneous rate constant, k 0 , and the transfer coefficient, α. Our method enabled the identification of inherent asymmetries in the ET kinetics arising during the reduction of ferrocene-based redoxmers, compared to their oxidation which displayed faster rate constants. Similar behavior was observed on a wide variety of carbon electrodes such as multi-layer graphene, highly ordered pyrolytic graphite, glassy carbon, and chemical vapor deposition-grown graphite films. However, aqueous systems and Pt do not exhibit such kinetic effects. Our analysis suggests that differential adsorption of the redoxmers is insufficient to account for our observations. Displaying a greater versatility than conventional electroanalytical methods, we demonstrate the operation of our spot analysis at concentrations up to 100 mM of redoxmer over graphite films. Looking forward, our method can be used to assess non-idealities in a variety of redoxmer/electrode/solvent systems with quantitative evaluation of kinetics for applications in redox-flow battery research.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Enabling technologies for the continuous electrically driven conversion of CO 2 and water to multi-carbon products at high current densities

Here, we demonstrate greatly improved conversion of CO 2 using a gas diffusion electrode (GDE) with flowing electrolyte configuration for CO 2 gas delivery in combination with a high surface area nickel phosphide electrocatalyst. This configuration achieves 40–50% selectivity for total carbon products over H 2 formation (HER) at total current densities ranging from 50 to 300 mA cm -2 . We developed a soft-templating method using CTAB detergent micelles for synthesis of phase-pure Ni 2 P, achieving a 260-fold larger surface area (BET) and porous sponge-like morphology that produces stable currents. This catalyst produces mainly one C-product, methylglyoxal (MG, C 3 H 4 O 2 ) with 38–47% overall selectivity, the highest reported selectivity for a 12-electron reduction product. The versatile soft-templating method for electrocatalyst synthesis uses low-temperature (185 °C) that is permissive for incorporation of co-catalysts that are otherwise destroyed by the high temperatures used in traditional solid-state synthesis (SSS). The non-porous Ni 2 P-SSS catalyst produces mainly H 2 at these current densities. Achieving these high currents and C/H selectivity benefits from use of hydrophobic polymers as co-catalyst binders (cationic = Nafion, anionic = PFAEM and neutral = PTFE) to improve CO 2 conversion. PFAEM is the better ionomer for the CO 2 RR at high current density, postulated as due to suppressing CO 2 conversion to inactive bicarbonate. Precipitation of the carbon products as a polycarbonate polymer occurs at high currents.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Artificial photosynthetic devices utilizing polariton antennas

An organic photovoltaic device comprises a substrate, a reflector positioned over the substrate, a first electrode positioned over at least a first portion of the reflector, a polaritonic antenna layer positioned over a second portion of the reflector different from the first portion, electrically connected to the first electrode, and at least one unit reaction cell positioned over at least part of the first electrode, the at least one unit reaction cell comprising a heterojunction layer comprising a donor material and an acceptor material, positioned over the first electrode, and a second electrode positioned over the heterojunction, wherein the polaritonic antenna and the reflector are configured to convert incoming photonic energy to polaritons. A method of fabricating an organic photovoltaic device is also disclosed.

Hou, Shaocong↗
DOE OSTI2022

A Hybrid Quantum–Classical Study of Ion Adsorption at the Copper Electrode

Here, we present a set of computational studies that surveys the molecular structure and thermodynamics of simple ions at the electrode–electrolyte interface. A hybrid quantum–classical approach is used to obtain free energy profiles and solvent structure as a function of the ion’s position relative to the electrochemical liquid/solid interface and system potential. Model systems consist of a copper electrode and single halide or alkali metal ion in contact with an implicit solvent and reveal new insights into the interplay of forces that drive or resist ion absorption at the electrode/ electrolyte interface. We also expand on subtleties of absorption site preference and describe the complex relationship between the energetic barrier to absorption and the ion–electrode binding energy as a function of electrode potential.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Ion Gating in Nanopore Electrode Arrays with Hierarchically Organized pH-Responsive Block Copolymer Membranes

Inspired by biological ion channels, artificial nanopore-based architectures have been developed for smart ion/molecular transport control with potential applications to iontronics and energy conversion. Advances in nanofabrication technology enable simple, versatile construction methods, and post-fabrication functionalization delivers nanochannels with unique ion transport-control attributes. Here, we characterize a pH-responsive, charge-selective dual-gating block copolymer (BCP) membrane composed of polystyrene-b-poly(4-vinylpyridine) (PS 48400 -b-P4VP 21300 ), capable of self-organizing into highly ordered nanocylindrical domains. Because the PS-b-P4VP membrane exhibits pH-dependent structural transitions, it is suitable for designing intelligent pH-gated biomimetic channels, for example, exhibiting on–off transport switching at pH values near the pK a of P4VP with excellent anion permselectivity at pH < pK a . Introducing the BCP membrane onto nanopore electrode arrays (BCP@NEAs) allows the BCP to serve as a pH-responsive gate controlling ion transfer into the NEA nanopores. Such selectively transported and confined ions are detected by using a 100 nm gap dual-ring nanoelectrode structure capable of enhancing current output by efficient redox cycling with an amplification factor >10 2 . In addition, BCP@NEAs exhibit extraordinary pH-gated ion selectivity, resulting in a 3380-fold current difference between anion and cation probes at pH 3.0. Furthermore, this hierarchically organized BCP-gated NEA system can serve as a template for the development of other stimulus-responsive ion gates, for example, those based on temperature and ligand gating, thus exploiting the intrinsic advantages of NEAs, such as enhanced sensitivity based on redox cycling, which may lead to technological applications such as engineered biosensors and iontronic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Positive Role of Fluorine Impurity in Recovered LiNi 0.6 Co 0.2 Mn 0.2 O 2 Cathode Materials

Lithium-ion battery (LIB) recycling is considered as an important component to enable industry sustainability. A massive number of LIBs in portable electronics, electric vehicles, and grid storage will eventually end up as wastes, leading to serious economic and environmental problems. Hence, tremendous efforts have been made to improve the hydrometallurgical recycling process because it is the most promising option for handling end-of-life LIBs owing to its wide applicability, low cost, and high productivity. Despite these advantages, some extra elements (Al, Fe, C, F, and so forth) remain as impurities in the removal process and are retained in the solution, which is a great challenge to obtain high-quality cathode materials. In this work, the impacts caused by fluorine impurity on the LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) cathode are intensively investigated via hydrometallurgical coprecipitation for the first time. Our results show that up to 1 at. % fluorine impurity brings a positive influence on the recovered material due to a higher Ni 2+ ratio on the surface of cathode particles. In addition, the presence of fluoride ions during coprecipitation could lead to the formation of holes in cathode particles, which improves the rate capability and cyclability dramatically. Compared to the virgin material, the capacity of the NCM622 material with 0.2 at. % fluorine impurity is boosted by ~8% (167.7 mA h/g) with a remarkable capacity retention of 98.0% after 100 cycles at 0.33 C. Besides, the cathode with 0.2 at. % fluorine impurity shows a far better rate performance, especially at high rates (~7% increased at 5 C) than that of virgin. Furthermore, these results convince that a low concentration of fluorine impurity is desirable in the hydrometallurgical recycling process. More importantly, this study offers implications in the design of high-performance NCM622 cathode materials via coprecipitation production with ion doping in the near future.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Hydroxyl Radical Suppression during Photoelectrocatalytic Water Oxidation on WO 3 |FeOOH

Depositing the earth-abundant water oxidation electrocatalyst FeOOH onto WO 3 has been shown to increase the Faradaic efficiency of the tandem WO 3 |FeOOH photoanode to near 100% for the photoelectrocatalytic oxidation of water to oxygen. Here we begin to explore how this gain in Faradaic efficiency is imparted through hydroxyl radical trap and Tafel experiments. It was found that increasing the FeOOH deposition time of the WO 3 |FeOOH caused a decrease in the quantity of hydroxyl radical trapped during photoelectrocatalytic water oxidation. Finally, these results, along with the disparate Tafel slopes of bare WO 3 and WO 3 |FeOOH, suggest a change in the water oxidation mechanism between the two materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Electrochemical Synthesis of Zeolite Coatings with Controlled Crystal Polymorphism and Self-Regulating Growth

Zeolite coatings are studied as molecular sieves for membrane separation, membrane reactors, and chemical sensor applications. They are also studied as anticorrosive films for metals and alloys, antimicrobial and hydrophobic films for heating, ventilation, and air conditioning, and dielectrics for semiconductor applications. Zeolite coatings are synthesized by hydrothermal, ionothermal, and dry-gel conversion approaches, which require high process temperatures and lengthy times (ranging from hours to days). Here, we report the first zeolite coatings synthesized via electrochemical deposition on a cathodic electrode, with controlled crystal polymorphism achieved within subhourly duration. We demonstrate this approach by developing sodium zeolite (e.g., sodalite (SOD), NaA (LTA), and Linde Type N (LTN)) coatings on a titanium electrode and extending the synthesis method to porous stainless steel. The coating morphology and crystallinity depend on the temperature, time, and applied current. The coating thickness is independent of the applied current, showing the presence of a self-regulating mechanism to ensure a uniform coating thickness across the metal surface. The electrochemical zeolite growth mechanism was elucidated with high-resolution transmission electron microscopy, and applications of the resultant zeolite coatings for oil/water separation and ethanol/water pervaporation were exploited. Electrochemical synthesis represents a novel, simple, fast, and environmentally friendly approach to preparing zeolite coatings. It can potentially be generalized for developing zeolite materials with diverse framework structures, morphologies, and orientations for substrates with complicated geometries.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Highly Active and Durable Air Electrodes for Reversible Protonic Ceramic Electrochemical Cells Enabled by an Efficient Bifunctional Catalyst

The commercialization of reversible protonic ceramic electrochemical cells is hindered by the lack of highly active and durable air electrodes exposed to high concentration of steam under operating conditions. We report findings that dramatically enhance the electrocatalytic activity and stability of a conventional (La 0.6 Sr 0.4 ) 0.95 Co 0.2 Fe 0.8 O 3-δ (LSCF) air electrode by a multiphase catalyst coating composed of a conformal Pr 1-x Ba x CoO 3-δ thin film and exsolved BaCoO 3-δ nanoparticles, are reported. At 600 °C, the catalyst coating decreases the polarization resistance of the LSCF air electrode by a factor of 25 (from 1.09 to 0.043 Ω cm 2 ) in air and the degradation rate by two orders of magnitude (from 1.0 × 10 -2 to 1.8 × 10 -4 Ω cm2 h -1 in humidified air with 30 vol% H2O). Further, a single cell with the catalyst-coated LSCF air electrode at 600 °C demonstrates a high peak power density of 1.04 W cm -2 in the fuel cell mode and a high current density of 1.82 A cm -2 at 1.3 V in the electrolysis mode. The significantly enhanced performance of the LSCF air electrode is attributed mainly to the high rate of surface oxygen exchange, fast surface proton diffusion, and the rapid H 2 O and O 2 dissociation on the catalysts.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Stochasticity at Scales Leads to Lithium Intercalation Cascade

Porous intercalation electrodes are synonymous with the promise of lithium-ion batteries toward electromobility. These electrodes exhibit stochastic geometrical features spanning different length scales. The implication of microstructural inhomogeneity on the lithium intercalation dynamics is hitherto unknown. In this work, starting from three-dimensional (3D), X-ray tomograms of intercalation electrode microstructures, we characterize the microstructural variability in porous intercalation electrodes. Furthermore, a physics-based analysis of electrochemical response reveals that the stochastic features can cause preferential lithiation fronts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Defect-free-induced Na + disordering in electrode materials

For reaching high-performance of electrode materials, it is generally believed that understanding the structure evolution and heterogeneous alignment effect is the key. Presently, a very simple and universally applicable self-healing method is investigated to prepare defect-free Prussian blue analogs (PBAs) that reach their theoretical capacity as cathode materials for sodium-ion batteries (SIBs). For direct imaging of the local structure and the dynamic process at the atomic scale, we deliver a fast ion-conductive nickel-based PBA that enables rapid Na + extraction/insertion within 3 minutes and a capacity retention of nearly 100% over 4000 cycles. This guest-ion disordered and quasi-zero-strain nonequilibrium solid–solution reaction mechanism provides an effective guarantee for realizing long-cycle life and high-rate capability electrode materials that operate via reversible two-phase transition reaction. Unconventional materials and mechanisms that enable reversible insertion/extraction of ions in low-cost metal–organic frameworks (MOFs) within minutes have implications for fast-charging devices, grid-scale energy storage applications, material discovery, and tailored modification.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Hydrogen evolution reaction catalyst

Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

08 HYDROGEN↗
DOE OSTI2020

Graphene macro-assembly-fullerene composite for electrical energy storage

Disclosed here is a method for producing a graphene macro-assembly (GMA)-fullerene composite, comprising providing a GMA comprising a three-dimensional network of graphene sheets crosslinked by covalent carbon bonds, and incorporating at least 20 wt. % of at least one fullerene compound into the GMA based on the initial weight of the GMA to obtain a GMA-fullerene composite. Also described are a GMA-fullerene composite produced, an electrode comprising the GMA-fullerene composite, and a supercapacitor comprising the electrode and optionally an organic or ionic liquid electrolyte in contact with the electrode.

25 ENERGY STORAGE↗