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At least 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

CO 2 Capture with Capsules of Ionic Liquid/Amines

Carbon capture remains an urgent issue that has gained a great deal of attention over the past few decades. Aqueous amines have excellent selectivity, but present corrosion and volatility issues, whereas ionic liquids (ILs) have negligible volatility and tunable physical properties, but high viscosities. One approach to improve the practical performance of these liquids is encapsulating them in a CO 2 permeable polymer shell to enhance the accessibility of the liquid and the CO 2 absorption rate. In this work, we report the encapsulation of a mixture of amine and IL (i.e., monoethanolamine (MEA) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF 4 ])) and demonstrate enhanced carbon capture performance. A soft-template approach and interfacial polymerization are used to give capsules with liquid core (64 wt %) and polyurea shell. Compared to the bulk liquid, the encapsulated liquid shows improved thermal stability over cycles of absorption at 25 °C, and desorption at 75 °C. The capsules with core of [BMIM][BF 4 ]-MEA show 0.2 mol CO 2 /kg of capsules at 1 bar CO 2 , compared to the bulk liquid, which has 0.05 mol CO 2 /kg of sorbent. This is attributed to the limited evaporation of the amines. Alternatively, the same capsules but with 5 wt % of piperazine (Pz) in the core have doubled gravimetric CO 2 capacity of the capsules (0.4 mol CO 2 /kg of capsules); performance is evaluated over 10 capture–release cycles showing minimal mass loss. Characterization of the CO 2 uptake of the polymer shell itself reveals that the shell contributes only ~10% of the observed capacity, likely attributed to amine functionalities of the polymer. Here, this facile approach to encapsulating such “active” liquids can be applied to other CO 2 selective solvents that are volatile, viscous, and corrosive.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Revolutionizing Porous Liquids: Stabilization and Structural Engineering Achieved by a Surface Deposition Strategy

Facile approaches capable of constructing stable and structurally diverse porous liquids (PLs) that can deliver high-performance applications are a long-standing, captivating, and challenging research area that requires significant attention. Here, in this work, a facile surface deposition strategy is demonstrated to afford diverse type III-PLs possessing ultra-stable dispersion, external structure modification, and enhanced performance in gas storage and transformation by leveraging the expeditious and uniform precipitation of selected metal salts. The Ag(I) species-modified zeolite nanosheets are deployed as the porous host to construct type III-PLs with ionic liquids (ILs) containing bromide anion , leading to stable dispersion driven by the formation of AgBr nanoparticles. The as-afforded type-III PLs display promising performance in CO 2 capture/conversion and ethylene/ethane separation. Property and performance of the as-produced PLs can be tuned by the cation structure of the ILs, which can be harnessed to achieve polarity reversal of the porous host via ionic exchange. The surface deposition procedure can be further extended to produce PLs from Ba(II)-functionalized zeolite and ILs containing [SO 4 ] 2– anion driven by the formation of BaSO 4 salts. The as-produced PLs are featured by well-maintained crystallinity of the porous host, good fluidity and stability, enhanced gas uptake capacity, and attractive performance in small gas molecule utilization.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Manipulate the Electronic and Magnetic States in NiCo 2 O 4 Films through Electric-Field-Induced Protonation at Elevated Temperature

Ionic-liquid-gating- (ILG-) induced proton evolution has emerged as a novel strategy to realize electron doping and manipulate the electronic and magnetic ground states in complex oxides. While the study of a wide range of systems (e.g., SrCoO 2.5 , VO 2 , WO 3 , etc.) has demonstrated important opportunities to incorporate protons through ILG, protonation remains a big challenge for many others. Furthermore, the mechanism of proton intercalation from the ionic liquid/solid interface to whole film has not yet been revealed. Here, with a model system of inverse spinel NiCo 2 O 4 , an increase in system temperature during ILG forms a single but effective method to efficiently achieve protonation. Moreover, the ILG induces a novel phase transformation in NiCo 2 O 4 from ferrimagnetic metallic into antiferromagnetic insulating with protonation at elevated temperatures. Finally, this study shows that environmental temperature is an efficient tuning knob to manipulate ILG-induced ionic evolution.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Recent Advances in the Chemistry of Hydrometallurgical Methods

Producing pure substances has been the obsession of scientists for centuries and has defined chemistry as we know it. Nowadays, most of our economy still relies on the chemist ability to extract and purify metallic elements from raw or recycled materials, which, in most cases, is done partly or entirely via hydrometallurgical methods. In this work, the authors present the critical aspects of this relatively overlooked, yet critical, chemistry discipline. This review article highlights the importance of hydrometallurgical processes for strategic industrial sectors, put in perspective traditional separation methods with emerging ones (new metal-binding chelators, ionic liquids, deep eutectic solvents, microfluidic devices, biomaterials, etc.), critically reviews progress made on separation methods over the past two decades, and highlights the challenges lying ahead for the hydrometallurgists in academia and the industry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

In situ polymerized succinonitrile-based solid polymer electrolytes for lithium ion batteries

Novel solid polymer electrolytes based on succinonitrile (SN) plastic crystal electrolyte (SN-PCE) and polymerized ionic liquid (PIL) has been successfully synthesized via an in-situ method. The fabricated electrolyte (PIL-SN-PCE) is uniformly inlayed into the supporting matrix of polyimide, which effectively ameliorates the mechanical properties of the electrolyte. PIL can effectively enhance the thermal stability of electrolytes up to 300 °C and mitigate the parasitic reactions between the electrolytes and the electrodes. PIL-SN-PCE exhibits a remarkable oxidation ability up to 5.4 V vs Li/Li + and a high room temperature ionic conductivity of 6.54 × 10 -4 S cm -1 . Furthermore, in-situ formed interface in PIL-SN-PCE guarantee an excellent compatibility with different electrodes, which can effectively improve the cycle stability and rate performances of both half-cells and full cells. Finally, PIL-SN-PCE is considered as a promising electrolyte for high energy density lithium-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2025

Fast lithium ion diffusion in brownmillerite Li x Sr 2 Co 2 O 5

Transition metal oxides not only exhibits novel magnetic properties but also provides outstanding ionic transports. Ionic conductors have great potential for interesting tunable physical properties via ionic liquid gating and novel energy storage applications such as all-solid-state lithium batteries. In particular, low migration barriers and high hopping attempt frequency are the keys to achieve fast ion diffusion in solids. Taking advantage of the oxygen-vacancy channel in Li x Sr 2 Co 2 O 5 , we show that migration barriers of lithium ion are as small as 0.28–0.17 eV depending on the lithium concentration rates. Our first-principles calculation also investigated hopping attempt frequency and concluded the room temperature ionic diffusivity and ion conductivity are high as 10 −7 –10 −6 cm 2 s −1 and 10 −3 –10 −2 Scm −1 , respectively, which outperform most of perovskite-type, garnet-type, and sulfide Li-ion solid-state electrolytes. This work proves Li x Sr 2 Co 2 O 5 as a promising super-ionic conductor.

Crystallographic defects↗
DOE OSTI2025

Sorbent Regeneration via Radiofrequency-Assisted Dielectric Heating for Direct Air Capture of CO 2

Direct air capture (DAC) of CO 2 is a negative emission technology that utilizes sorbents requiring a regeneration step for repeated ab(/d)sorption–desorption cycles. Here we report an unconventional approach to desorb captured CO 2 from a porous sorbent using radiofrequency (RF) irradiation for dielectric heating and targeted energy transfer, thus enabling modularity and promoting renewable energy input. Regeneration of composites of functional ionic liquid and metal–organic framework with high CO 2 capacity and enhanced transport is demonstrated under conditions relevant to DAC. RF-assisted dielectric heating at the megahertz frequency range shows effective absorption of electromagnetic energy and consequently rapid release of the captured CO 2 .

Ionic liquids↗
DOE OSTI2024

CONVENTIONAL SUPERCAPACITOR ELECTROLYTES: AQUEOUS, ORGANIC, AND IONIC

This chapter thoroughly covers the most recent developments of aqueous and non-aqueous electrolytes for electrochemical supercapacitors (ESs). In more detail, the overview of different types of electrolytes and their featured properties are initially introduced. Thereafter, the conventional aqueous electrolyte was first discussed, summarized, and opened the perspectives of some new salts that can be used to enhance the ionic conductivity and the performance of supercapacitor. The organic electrolytes, including the organic solvents/salt, ionic liquids, and deep eutectic, are the main parts to explore different trends and cutting-edge advances in optimizing electrolyte formulations customized for different electrode materials. Furthermore, the discussion on the current obstacles and prospects of these electrolytes is also underlined.

electrochemical capacitors, aqueous electrolyte, o↗
DOE OSTI2018

Dynamic Field Modulation of the Octahedral Framework in Metal Oxide Heterostructures

Control over the oxygen octahedral framework is widely recognized as key to the design of functional properties in perovskite oxide heterostructures. Although the oxygen octahedral framework can be manipulated during synthesis, the as-grown oxygen octahedra generally remain fixed, preventing the development of adaptive behavior in electronic and ionotronic systems. Here, it is demonstrated that the oxygen octahedral framework can be dynamically and reversibly manipulated by an electric field through the coupling with oxygen vacancies. Studying model WO 3 heterostructures during ionic liquid gating with a combination of in situ X-ray scattering and spectroscopy, it is shown that large changes in electronic properties can arise due to the increased flexibility of the octahedral network at high vacancy concentrations. Furthermore, the results describe a generic framework for the construction of dynamic systems and devices with an array of field-tunable properties.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Quantification of [MTBD][beti] loading and its effects on Pt/HSC electrode performance in hydrogen fuel cells

High surface area carbon-supported platinum catalysts (Pt/HSC) are widely used in polymer electrolyte membrane fuel cells but often suffer from limited proton and oxygen transport within porous domains. To address these challenges, we integrate the ionic liquid [MTBD][beti] into Pt/HSC catalyst layers using two deposition methods-one-pot and sequential deposition-to tune IL distribution within micropores and mesopores. A combination of ex situ and in operando techniques were employed to elucidate electrode structure-performance relationships across a range of IL loadings. Sequential deposition achieved more efficient pore filling and higher IL retention at lower IL:C ratios, enabling enhanced proton conductivity and protection of active sites. Compared to the IL-free Pt/HSC, IL-modified electrodes demonstrated up to 28% improvement in mass activity and enhanced high-current-density performance under low relative humidity, while maintaining comparable performance under humidified conditions. Electrochemical impedance spectroscopy and CO displacement experiments reveal that improvements are linked to reduced ionic resistance and lower sulfonate adsorption on Pt sites, rather than changes in electrochemical surface area. However, excessive IL loading leads to mass transport losses. These results highlight the importance of selective pore filling and efficient IL distribution in achieving kinetic gains without compromising ionic and gas transport.

08 HYDROGEN↗
DOE OSTI2026

Higher Wood Density Lowers Feedstock Cost and Has Minimal Impact on Biomass Conversion to Biofuels

Poplar and other woody feedstocks have the potential to provide up to 200 million tons of biomass per year that can be converted to liquid fuels. Most forestry strategies that aim to increase biomass productivity per hectare rely on short rotation plantations of fast-growing varieties. The improvement of the wood density as a key trait itself has largely been overlooked. We evaluated natural variation in wood density across a population of genetically diverse Populus trichocarpa trees grown in a common garden. Wood density varies greatly within this population but is heritable; higher wood density was not systematically associated with reduced growth, challenging assumptions of a trade-off between wood density and biomass accumulation. Furthermore, denser wood led to significant improvements throughout the supply chain including lowering biomass production and transportation costs. Higher density did not correlate with changes in biomass composition. Density did not impact bioconversion in the two feedstock-to-fuel pipelines tested (pretreatment by ionic liquids and fermentation to bisabolene or soaking in aqueous ammonia and fermentation to ethanol) on a representative subset of poplars. These findings highlight wood density as a promising breeding target for accelerating the development of high-yielding, conversion-efficient bioenergy crops and as an avenue for increasing landuse efficiency and reducing biomass transportation cost.

09 BIOMASS FUELS↗
DOE OSTI2014

Length scale selects directionality of droplets on vibrating pillar ratchet

Directional control of droplet motion at room temperature is of interest for applications such as microfluidic devices, self-cleaning coatings, and directional adhesives. Here, arrays of tilted pillars ranging in height from the nanoscale to the microscale are used as structural ratchets to directionally transport water at room temperature. Water droplets deposited on vibrating chips with a nanostructured ratchet move preferentially in the direction of the feature tilt while the opposite directionality is observed in the case of microstructured ratchets. This remarkable switch in directionality is consistent with changes in the contact angle hysteresis. To glean further insights into the length scale dependent asymmetric contact angle hysteresis, the contact lines formed by a nonvolatile room temperature ionic liquid placed onto the tilted pillar arrays were visualized and analyzed in situ in a scanning electron microscope. As a result, the ability to tune droplet directionality by merely changing the length scale of surface features all etched at the same tilt angle would be a versatile tool for manipulating multiphase flows and for selecting droplet directionality in other lap-on-chip applications.

42 ENGINEERING↗
DOE OSTI2023

Applications of biomass-derived solvents in biomass pretreatment – Strategies, challenges, and prospects

We report biomass pretreatment is considered a key step in the 2nd generation biofuel production from lignocellulosic biomass. Research on conventional biomass pretreatment solvents has mainly been focused on carbohydrate conversion efficiency, while their hazardousness and/or carbon intensity were not comprehensively considered. Recent sustainability issues request further consideration for eco-friendly and sustainable alternatives like biomass-derived solvents. Carbohydrate and lignin-derived solvents have been proposed and investigated as green alternatives in many biomass processes. In this review, the applications of different types of biomass pretreatment solvents, including organic, ionic liquid, and deep eutectic solvents, are thoroughly discussed. The role of water as a co-solvent in these pretreatment processes is also reviewed. Finally, current research challenges and prospects of utilizing biomass-derived pretreatment solvents for pretreatment are discussed. Given bioethanol's market potential and increasing public awareness about environmental concerns, it will be a priority adopting sustainable and green biomass pretreatment solvents in biorefinery.

09 BIOMASS FUELS↗
DOE OSTI2023

Ionothermally Synthesized Nanoporous Ti 0.95 W 0.05 Nb 2 O 7 : a Novel Anode Material for High-Performance Lithium-Ion Batteries

Although TiNb 2 O 7 is regarded as a fast-rechargeable lithium-ion battery (LIB) anode material, the intrinsic poor electrochemical kinetics of TiNb 2 O 7 still dramatically impedes its development. Herein, an ionothermal synthesis-assisted doping strategy is proposed for the preparation of a new W 6+ -doped TiNb 2 O 7 material (Ti 0.95 W 0.05 Nb 2 O 7 ) with nanoporous structure (denoted as NPTWNO). The improved Li + diffusion coefficient of NPTWNO suggests that the ionic-liquid-templated nanoporous architecture improves the Li+ diffusion kinetics. The density functional theory computational study reveals that the doped W 6+ successfully boosts the electronic conductivity due to the narrowed conduction-valance bandgap resulted from charge redistribution, which is reflected by the electrochemical impedance spectroscopy data. With the simultaneously enhanced Li+ diffusivity and electronic conductivity, NPTWNO achieves fast-rechargeability in LIBs. So this work indicates the potential of ionothermal synthesis-assisted doping strategy on energy storage materials and offers NPTWNO material with promising electrochemical performance.

25 ENERGY STORAGE↗
DOE OSTI2019

Recent Advances in the Design of Ionenes: Toward Convergence with High–Performance Polymers

Ionenes, condensation polymers wherein the charge (typically cationic) lies directly within the polymer backbone, have been known for over 85 years. Historically, ionenes have been synthesized from 3° diamines and α,ω-dihaloalkanes, forming chains of ammonium cations tethered by flexible hydrocarbon linkages with “free” halide anions. However, the requisite building blocks of ionenes are by no means limited only to such molecules. In recent years, ionenes with more sophisticated backbone chemistries have been produced, with a trend toward the use of functionalities associated with classical “high-performance” condensation polymers such as polyimides and polyarylamides. The expansion of ionenes is also catalyzed by the rapid growth of research in imidazolium-based ionic liquids (ILs), wherein the combination of ionenes with ILs can yield unexpected behaviors. Furthermore, when considering the largely unexplored experimental space in anionic ionenes, the opportunities for new materials are virtually endless. Furthermore, this review primarily focuses on developments in ionenes published in the scientific literature since 2010, but also includes some older examples that may not have received sufficient attention at the time of their original publication yet can provide some key lessons for the future of ionene design.

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

Wear penalty for steel rubbing against hard coatings in reactive lubricants due to tribochemical interactions

Hard coatings and surface adsorptive/reactive lubricants are two common strategies for improving wear protection, but what if they are used together? In this study, steel-steel and steel-coating sliding was investigated in boundary lubrication of polar and non-polar oils containing a ZDDP or an ionic liquid. Two hard coatings, diamond-like-carbon (DLC) and chromium nitride (CrN), were used. Furthermore, for a steel-steel contact, wear was effectively reduced by using a more surface reactive lubricant, as expected. However, the steel ball wear was increased against a hard coating and further worsened with a more polar oil and/or a more surface reactive additive. The wear mechanism is proposed as a combined effect of physicochemical interactions with the lubricant, mechanical polishing by the counterface, and material adhesion.

36 MATERIALS SCIENCE↗