A5076186349- Synthesis and properties of polymers
- Silicone and Siloxane Chemistry
- Epoxy Resin Curing Processes
- Advancements in Battery Materials
- Advanced Battery Materials and Technologies
- Laser Material Processing Techniques
- Supercapacitor Materials and Fabrication
- Fiber-reinforced polymer composites
- Advanced Battery Technologies Research
- Laser-induced spectroscopy and plasma
- Graphene research and applications
- Advanced battery technologies research
- Synthetic Organic Chemistry Methods
- Mechanical Behavior of Composites
- Surface Modification and Superhydrophobicity
- Tribology and Wear Analysis
- Surface Roughness and Optical Measurements
- Polymer Nanocomposite Synthesis and Irradiation
- Flame retardant materials and properties
- Adhesion, Friction, and Surface Interactions
- Polymer Nanocomposites and Properties
- Space Exploration and Technology
- Planetary Science and Exploration
- Spacecraft Design and Technology
- Thermodynamic and Exergetic Analyses of Power and Cooling Systems
Langley Research Center
2014-2023
Hampton University
2018
National Aeronautics and Space Administration
2002-2005
Virginia Commonwealth University
1987-1989
University of Massachusetts Amherst
1974-1975
University of California, Berkeley
1966
Carl Zeiss (Germany)
1966
Optica
1966
Metal-air batteries, especially Li-air have attracted significant research attention in the past decade. However, electrochemical reactions between CO2 (0.04 % ambient air) with Li anode may lead to irreversible formation of insulating Li2 CO3 , making battery less rechargeable. To make Li-CO2 batteries usable under conditions, it is critical develop highly efficient catalysts for reduction and evolution investigate behavior batteries. Here, we demonstrate a rechargeable high reversibility...
A highly porous 2D nanomaterial, holey graphene oxide (hGO), is synthesized directly from powder and employed to create an aqueous 3D printable ink without the use of additives or binders. Stable dispersions hydrophilic hGO sheets in water (≈100 mg mL-1 ) can be readily achieved. The shear-thinning behavior enables extrusion-based printing fine filaments into complex architectures, such as stacked mesh structures, on arbitrary substrates. freestanding printed meshes exhibit trimodal...
Graphene has attracted a lot of attention for ultracapacitor electrodes because its high electrical conductivity, surface area, and superb chemical stability. However, poor volumetric capacitive performance typical graphene-based hindered their practical applications the extremely low density. Herein we report scalable synthesis method holey graphene (h-Graphene) in single step without using any catalysts or special chemicals. The film made as-synthesized h-Graphene exhibited relatively...
A highly efficient cathode catalyst for rechargeable Li-CO2 batteries is successfully synthesized by implanting single iron atoms into 3D porous carbon architectures, consisting of interconnected N,S-codoped holey graphene (HG) sheets. The unique hierarchical architecture the with a large surface area and sufficient space within HG framework can not only facilitate electron transport CO2 /Li+ diffusion, but also allow high uptake Li2 CO3 to ensure capacity. Consequently, resultant exhibit...
Topology is critical for properties and function of 2D nanomaterials. Membranes films from nanomaterials usually suffer large tortuosity as a result dense restacking the nanosheets thus have limited utility in applications such electrodes supercapacitor batteries, which require ion transport through nanosheet thickness. In comparison with conventional porous nanomaterials, introducing holes to create holey retention 2D‐related more viable approach improve molecular transport. Here, graphene...
Abstract Li‐CO 2 batteries have attracted ever increasing attention due to their high energy and power densities. However, Li CO 3 formed during the discharge process is difficult decompose, leading a large charge overpotential poor cyclability. Thus, high‐performance low‐cost catalysts that can be integrated into electrode architecture are urgently needed for development of practical with low long Herein, composite catalyst reported based on carbon quantum dots supported by holey graphene...
Lithium–oxygen (Li–O2) batteries have the highest theoretical energy density of all Li-based storage systems, but many challenges prevent them from practical use. A major obstacle is sluggish performance air cathode, where both oxygen reduction (discharge) and evolution (charge) reactions occur. Recently, there been significant advances in development graphene-based cathode materials with a large surface area catalytically active for reactions, especially additional catalysts or dopants....
A flexible high-performance lithium–CO<sub>2</sub> battery is developed using wood-based cathode as a novel platform for combining CO<sub>2</sub> utilization and energy storage.
Li–air batteries represent cutting edge electrochemical energy storage devices, but their practical applications have been precluded by the high cathode cost, low discharge/charge efficiency, and/or short battery lifetime. Here, we developed a low-cost, very efficient, air electrode from porous nitrogen-doped holey graphene for rechargeable nonaqueous Li–O2 cells. The resultant cell can deliver round-trip efficiency (85%) and long cycling life (>100 cycles) under controlled depths or...
Nitrogen-doped holey graphene (N-hG) as an anode material for lithium-ion batteries has delivered a maximum volumetric capacity of 384 mAh cm−3 with excellent long-term cycling life up to 6000 cycles, and electrochemical capacitor energy density 171.2 Wh L−1 capacitance 201.6 F cm−3. As service our authors readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed may be re-organized online delivery, but not copy-edited or typeset....
Holey graphene (hG), also called nanomesh, is a structural derivative of graphene. hG formed by removing large number atoms from the graphitic plane to produce holes distributed on and through atomic thickness sheets. These holes, sometimes with abundant functional groups around their edges, impart properties that are uncommon intact but advantageous toward various applications. In this review, strategies prepare related applications take advantage unique motif these materials discussed....
For commercial applications, the need for smaller footprint energy storage devices requires more to be stored per unit area. Carbon nanomaterials, especially graphene, have been studied as supercapacitor electrodes and can achieve high gravimetric capacities affording densities. However, most nanocarbon-based exhibit a significant decrease in their areal capacitances when scaled mass loadings typically used commercially available cells (∼10 mg/cm2). One of reasons this behavior is that...
To address the multitude of issues that accompany wet electrode fabrication techniques, composite lithium-ion battery (LIB) electrodes composed solely active components (active material and conductive additive) are fabricated using a scalable eco-friendly dry processing method known as pressing. accomplish this, nanoporous carbon allotrope (i.e., holey graphene or hG) acts compressible matrix to accommodate incompressible cathode anode powders. The inherent nanoporosity facilitates escape...
Polyimides with a combination of properties including low solar absorptivity (α) in thin films, atomic oxygen (AO), and ultraviolet (UV) radiation resistance, solubility organic solvents the imide form, high glass transition (Tg) temperatures, thermal stability have been prepared characterized. The polymers were by reacting novel aromatic diamine, [2,4-bis(3-aminophenoxy)phenyl]diphenylphosphine oxide (2), dianhydrides polar aprotic solvent. diamine was from commercially available starting...
By creating holes in 2D nanosheets, tortuosity and porosity can be greatly tunable, which enables a fast manufacturing process (i.e., removal of gas solvent) toward various nanostructures. We demonstrated outstanding compressibility holey graphene is impossible for pristine graphene. Holey powder easily compressed into dense strong monoliths with different shapes at room temperature without using any solvents or binders. The remarkable graphene, sharp contrast not only the fabrication...
ConspectusHoley graphene (hG) is a structural derivative of with arrays through-thickness holes few to tens nanometers in diameter, randomly distributed across the nanosheet surfaces. In most bulk preparation methods, on hG sheets are preferentially generated from pre-existing defects graphene. Therefore, contrary intuitive belief, not necessarily more defective than intact Instead, it retains essential parent properties, including high electrical conductivity, surface area, mechanical...
Practical approaches are needed to take advantage of the nanometer-scale mechanical properties carbon nanotubes (CNTs) at macroscopic scale. This study was conducted elucidate salient factors that can maximize nanocomposites fabricated from commercially available CNT sheets. The sheets were modified by stretching improve alignment and in situ polymerization using polyaniline (PANI), a π-conjugated conductive polymer, as binder. resulting subsequently postprocessed hot pressing and/or high...