A5024130743- Carbon Nanotubes in Composites
- Advanced Photocatalysis Techniques
- Quantum Dots Synthesis And Properties
- 2D Materials and Applications
- Graphene research and applications
- Catalytic Processes in Materials Science
- Chalcogenide Semiconductor Thin Films
- Electron and X-Ray Spectroscopy Techniques
- Nanowire Synthesis and Applications
- Copper-based nanomaterials and applications
- Advanced Nanomaterials in Catalysis
- Molecular Junctions and Nanostructures
- MXene and MAX Phase Materials
- Advanced biosensing and bioanalysis techniques
- TiO2 Photocatalysis and Solar Cells
- Catalysis and Oxidation Reactions
- CO2 Reduction Techniques and Catalysts
- Advanced Electron Microscopy Techniques and Applications
- Force Microscopy Techniques and Applications
- Electromagnetic Launch and Propulsion Technology
- Nanotechnology research and applications
- Perovskite Materials and Applications
- Electrochemical Analysis and Applications
- Energetic Materials and Combustion
- Advanced Condensed Matter Physics
United States Naval Research Laboratory
2016-2025
Sensors (United States)
2013-2023
United States Navy
2015-2020
Naval Research Laboratory Materials Science and Technology Division
2016
Physical Sciences (United States)
2008
Supercon (United States)
2008
University of Maryland, College Park
2002-2008
Stanford University
2008
DEVCOM Army Research Laboratory
2005-2006
A high-mobility (9000 cm2/V·s) semiconducting single-walled nanotube transistor is used to construct a nonvolatile charge-storage memory element operating at room temperature. Charges are stored by application of few volts across the silicon dioxide dielectric between and substrate, detected threshold shift field-effect transistor. The high mobility allows observation discrete configurations charge corresponding rearrangement single or electrons. These states may be reversibly written, read,...
Activities of Cu nanoparticles supported on carbon black (VC), single-wall nanotubes (SWNTs), and Ketjen Black (KB) toward CO2 electroreduction to hydrocarbons (CH4, C2H2, C2H4, C2H6) are evaluated using a sealed rotating disk electrode (RDE) setup coupled gas chromatograph (GC). Thin films catalysts deposited RDE tips following procedure well-established in the fuel cell community. Lead (Pb) underpotential deposition (UPD) is used determine electrochemical surface area (ECSA) thin 40 wt %...
Recently, significant interest has emerged in fabricated systems that mimic the behavior of geometrically frustrated materials. We present full realization such an artificial spin ice system on a two-dimensional kagome lattice and we demonstrate rigid adherence to local rule by directly counting individual pseudospins. The resulting configurations show not only rules long-range disorder, but also correlations consistent with Monte Carlo calculations. Our results suggest dipolar corrections...
We report direct observation of controlled and reversible switching magnetic domains using static (dc) electric fields applied in situ during Lorentz microscopy. The is realized through electromechanical coupling thin film Fe0.7Ga0.3/BaTiO3 bilayer structures mechanically released from the growth substrate. domain wall motion observed dynamically, allowing association local ordering throughout a range fields. During application ∼7−11 MV/m to piezoelectric BaTiO3 film, rearrange ferromagnetic...
We demonstrate plasmonic enhancement of visible-light-driven splitting water at three-dimensionally (3D) networked gold–titania (Au–TiO2) aerogels. The sol–gel-derived ultraporous composite nanoarchitecture, which contains 1 to 8.5 wt% Au nanoparticles and titania in the anatase form, retains high surface area mesoporosity unmodified TiO2 aerogels maintains stable dispersion ∼5 nm guests. A broad plasmon resonance (SPR) feature centered ∼550 is present for Au–TiO2 aerogels, but not Au-free...
We report on preparation dependent properties observed in monolayer WS2 samples synthesized via chemical vapor deposition (CVD) a variety of common substrates (Si/SiO2, sapphire, fused silica) as well that were transferred from the growth substrate onto new substrate. The as-grown CVD materials (as-WS2) exhibit distinctly different optical than (x-WS2). In case Si/SiO2, following transfer to fresh Si/SiO2 there is ~50 meV shift ground state exciton higher emission energy both...
The extended interface between Cu nanoparticles and TiO<sub>2</sub> aerogel supports stabilizes against oxidation enough to preserve its plasmonic behavior, even after exposure air.
Thermal transport in carbon nanotubes is explored using different laser powers to heat suspended single-walled ∼5μm length. The temperature change along the length of a nanotube determined from temperature-induced shifts G band Raman frequency. spatial profile reveals ratio contact thermal resistance intrinsic nanotube. Moreover, obtained profiles allow differentiation between diffusive and ballistic phonon transport. Diffusive observed all measured found range 0.02 17.
The fabrication of well‐separated, narrow, and relatively smooth silicon nanowires with good periodicity is demonstrated, using non‐close‐packed arrays nanospheres precisely controlled diameters, pitch, roughness. Controlled reactive ion etching in an inductively coupled plasma reduces the self‐assembled to approximately a tenth their original diameter, while retaining surface smoothness periodic placement. A titanium adhesion layer between substrate gold film allows much thinner catalyst...
We demonstrate the use of field-emission scanning electron microscopy for rapid imaging small-diameter carbon nanotubes on insulating SiO2 substrates. The image contrast stems from local potential differences between nanotube and substrate is insensitive to surface roughness defects. This technique may also be used as a probe electrical connectivity small structures without external leads.
Abstract Compelling evidence suggests distinct correlated electron behavior may exist only in clean 2D materials such as 1T-TaS 2 . Unfortunately, experiment and theory suggest that extrinsic disorder free standing layers disrupts correlation-driven quantum behavior. Here we demonstrate a route to realizing fragile states through endotaxial polytype engineering of van der Waals materials. The true isolation charge density waves (CDWs) between metallic stabilizes commensurate long-range order...
Bismuth has been investigated as a potential n-type dopant in hybrid lead halide perovskites, but its behavior all-inorganic perovskites such CsPbBr3 not thoroughly characterized. We show that Bi behaves deep defect and gives rise to broad near-infrared emission, similar phenomenon previously reported CsPbBr3. Using inverse temperature crystallization, we synthesized series of Bi-doped crystals quantified their concentrations by inductively coupled plasma optical emission spectroscopy....
Individual carbon nanotubes (CNTs) often occur in randomly dispersed two-dimensional as well three-dimensional configurations that make device fabrication difficult. Making electrical contact to such CNTs is of practical interest. To this end, we individual metallic single-walled (SWNTs) using the focused electron-beam-induced deposition (FEBID) pure gold. The SWNTs are grown by chemical vapor on a flat substrate, and gold leads made through FEBID inorganic precursor gas,...
Single-walled carbon nanotubes (SWNTs) have been grown via chemical vapor deposition on high-kappa dielectric SrTiO3/Si substrates, and high-performance semiconducting SWNT field-effect transistors fabricated using the thin SrTiO3 as gate Si electrode. The transconductance per channel width is 8900 S/m. high cannot be explained by increased capacitance; it proposed that electric field at nanotube-electrode interface due to decreases or eliminates Schottky barrier.
Comparison of methanol photochemistry at three-dimensionally (3D) networked aerogels TiO2 or Au–TiO2 reveals that incorporated Au nanoparticles strongly sensitize the oxide nanoarchitecture to visible light. Methanol dissociatively adsorbs surfaces and under dark, high-vacuum conditions. Upon irradiation either ultraporous material with broadband UV light anaerobic conditions, adsorbed methoxy groups act as hole-traps extend conduction-band shallow-trapped electron lifetimes. A higher...
We use intensity-modulated photovoltage spectroscopy (IMVS) and photocurrent (IMPS) to characterize carrier dynamics in titania (TiO2) aerogels under photocatalytic conditions. By systematically increasing the weight fraction of sol–gel precursor during TiO2 synthesis, we are able impart drastic changes transport/trapping improve activity for two mechanistically divergent photochemical reactions: reductive water splitting (H2 generation) oxidative degradation dichloroacetate (DCA). The...
Bismuth oxide is an important bismuth compound having applications in electronics, photo-catalysis and medicine. At the nanoscale, experiences a variety of new physico-chemical properties because its increased surface to volume ratio leading potentially applications. In this manuscript, we report for very first time synthesis (Bi2O3) nano-flakes by pulsed laser ablation liquids without any external assistance (no acoustic, electric field, or magnetic field). The was performed irradiating,...
The progress of semiconductor electronics toward ever-smaller length scales and associated higher power densities brings a need for new high-resolution thermal microscopy techniques. Traditional is performed by detecting infrared radiation with far-field optics, where the resolution limited wavelength light. By adopting serial, local-probe approach, near-field scanned-probe microscopies can surpass this limit but sacrifice imaging speed. In same way that electron was invented to overcome...
We use plasmonic Au–TiO2 aerogels as a platform in which to marry synthetically thickened particle–particle junctions TiO2 aerogel networks Au∥TiO2 interfaces and then investigate their cooperative influence on photocatalytic hydrogen (H2) generation under both broadband (i.e., UV + visible light) visible-only excitation. In doing so, we elucidate the dual functions that incorporated Au can play water reduction cocatalyst sensitizer. also photodeposit non-plasmonic Pt nanoparticles into our...
The interaction between two-dimensional crystals (2DCs) and metals is ubiquitous in 2D material research. Here we report how 2DC overlayers influence the recrystallization of relatively thick metal films subsequent synergetic benefits this provides for coupling surface plasmon-polaritons (SPPs) to photon emission semiconductors. We show that annealing 2DC/Au on SiO2 results a 'reverse epitaxial' process where initially nanocrystalline Au become highly textured close crystallographic registry...
We determine the activity of catalytic carbon monoxide (CO) oxidation as a function size gold nanoparticles (Au NP), their weight loading, and interfacial intimacy with similarly sized TiO2 NPs covalently bonded in an aerogel support. use this Au+TiO2 series to correlate mechanisms that influence including hot electron injection production, electron–hole pair formation, oxygen vacancy content, electronic metal–support interaction (EMSI) stemming from photoinduced charge transfer Au. The Au...
Purifying hydrogen feedstocks necessitates preferential oxidation of carbon monoxide (COPROX), but traditional precious metal catalysts are poorly selective, while transition suffer from insufficient activity and stability. We report that Cu nanoparticles supported on CeO2 or Gd(III)-substituted (GCO) aerogels deliver a rare combination high activity, selectivity, stability for COPROX. The reducing oxide disperses stabilizes its more active low-valent state. Aerogel-supported oxidizes CO at...