A5031914826- Advanced Electron Microscopy Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- Ammonia Synthesis and Nitrogen Reduction
- Advanced Photocatalysis Techniques
- Gold and Silver Nanoparticles Synthesis and Applications
- nanoparticles nucleation surface interactions
- Copper-based nanomaterials and applications
- Laser-Matter Interactions and Applications
- Force Microscopy Techniques and Applications
- MXene and MAX Phase Materials
- Electronic and Structural Properties of Oxides
- Quantum, superfluid, helium dynamics
- Laser-Plasma Interactions and Diagnostics
- Advanced battery technologies research
- Green IT and Sustainability
- Chalcogenide Semiconductor Thin Films
- Semiconductor Quantum Structures and Devices
- Laser-Ablation Synthesis of Nanoparticles
- Electrochemical Analysis and Applications
- Quantum Dots Synthesis And Properties
- Electrocatalysts for Energy Conversion
- Gas Sensing Nanomaterials and Sensors
- Advancements in Battery Materials
- CO2 Reduction Techniques and Catalysts
- Advanced Battery Materials and Technologies
Material Physics Center
2025
Sandia National Laboratories
2025
Sandia National Laboratories California
2024
University of Illinois Urbana-Champaign
2020-2024
University of North Carolina at Chapel Hill
2016-2018
Applied Physical Sciences (United States)
2016
Ammonia is a promising liquid-phase carrier for the storage, transport, and deployment of carbon-free energy. However, realization an ammonia economy predicated on availability green methods production powered by electricity from renewable sources or solar Here, we demonstrate synthesis ammonium nitrate synergistic combination light. We use electrocatalyst composed gold nanoparticles, which have dual attributes electrochemical reduction activity visible-light-harvesting ability due to their...
Because of their loosely bound electrons, electrides offer physical properties useful in chemical synthesis and electronics. For these applications others, nanosized advantages, but to-date no electride has been synthesized as a nanomaterial. We demonstrate experimentally that Ca2N, layered which layers atoms are separated by 2D electron gas (2DEG), can be exfoliated into two-dimensional (2D) nanosheets using liquid exfoliation. The flakes stable nitrogen atmosphere or select organic...
Understanding the limits of spatiotemporal carrier dynamics, especially in III-V semiconductors, is key to designing ultrafast and ultrasmall optoelectronic components. However, identifying such properties controlling them has been elusive. Here, using scanning electron microscopy, bulk n-GaAs p-InAs, we simultaneously measure picosecond dynamics along with three related quantities: subsurface band bending, above-surface vacuum potentials, surface trap densities. We make two unexpected...
BiVO4 photoanodes are promising for solar water splitting, with photogenerated electrons and holes preferentially reacting at top {010} lateral {110} facets, respectively. However, the mechanisms driving this facet-dependent reactivity remain unclear. Here, we investigate photocurrent material heterogeneity using correlative scanning photoelectrochemical microscopy (SPCM), electron beam induced current (EBIC) mapping, mid-IR scattering near-field optical (s-SNOM). SPCM measurements of 62...
Abstract Understanding and controlling ultrafast charge carrier dynamics is of fundamental importance in diverse fields (quantum) science technology. Here, we create a three-dimensional hot electron gas through two-photon photoemission from copper surface vacuum. We employ an microscope to record movies the subsequent on picosecond-nanosecond time scale. After prompt Coulomb explosion, characterized by rapid oblate-to-prolate shape transformation gas, periodic long-lived cyclotron...
Metal nanoparticles are attracting interest for their light-absorption properties, but such materials known to dynamically evolve under the action of chemical and physical perturbations, resulting in changes structure composition. Using a transmission electron microscope equipped optical excitation specimen, structural evolution Cu-based simultaneous beam irradiation plasmonic was investigated with high spatiotemporal resolution. These initially have Cu core-Cu2O oxide shell structure, over...
Light-absorbing plasmonic nanostructures are used in a variety of applications, including photocatalysis and sensing. Because structure is intricately linked to function performance, it essential understand how the structures these materials might evolve under light excitation what types atomic natures structural transformations. Using transmission electron microscope equipped with capability laser specimen, we monitored Au–Cu alloy nanoparticles excitation. Plasmonic was found induce...
Electrochemical reactivity is known to be dictated by the structure and composition of electrocatalyst-electrolyte interface. Here, we show that optically generated electric fields at this interface can influence electrochemical insofar as completely switch reaction selectivity. We study an electrocatalyst composed gold-copper alloy nanoparticles active toward reduction CO
Graphite has been extensively studied as a battery electrode, but few investigations have explored its behavior in water at neutral pH. Here, we investigate graphite intercalation an aqueous ammonium sulfate electrolyte with pH of 6. We identified potentials which bisulfate and deintercalation compete oxidation. In situ X-ray diffraction revealed that the interlayer space expands during intercalation, reaching stage-two compound. Irreversible changes to occurred demonstrated by appearance...
Alloying on the nanoscale is a powerful chemical handle for tuning structural, electronic, and optical properties through continuous composition variation. Here, we explore impact of alloying structural optoelectronic copper chalcogenide nanocrystals. Cuprous selenide–sulfide alloy nanocrystals were made by cation exchange reaction. The upon oxidation exhibit localized surface plasmon resonances. resonance frequency follows an anomalous trend as function composition. Similar behavior seen...
Scanning electron microscopy (SEM), a century-old technique, is today ubiquitous method of imaging the surface nanostructures. However, most SEM detectors simply count number secondary electrons from material interest, and thereby overlook rich information contained within them. Here, by simple modifications to standard tool, we resolve momentum energy on directly plume generated beam SEM. Leveraging these spectroscopic capabilities, our technique able image lateral electric fields across...
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