A simple and environmentally benign technology for synthesizing ultrasmall CuInanoparticles (NPs) on the surface of the food additive hydroxypropyl methylcellulose (HPMC) and their application in completely organic solvent‐free tandem alkyne‐azide cycloaddition reactions were reported. The NP catalyst was thoroughly characterized by high‐angle annular dark‐field scanning transmission electron microscopy, high‐resolution transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy analysis for its morphology, particle size distribution, chemical composition, and oxidation state analyses. The NP catalyst was highly efficient, affording products in 10–45 min. All products were obtained in high purity by simple filtration, obviating organic solvents from the reaction set‐up to product isolation. The methodology is general and scalable as validated by a broad substrate scope.
Plasmonic photocatalysis uses the light-induced resonant oscillation of free electrons in a metal nanoparticle to concentrate optical energy for driving chemical reactions. By altering the joint electronic structure of the catalyst and reactants, plasmonic catalysis enables reaction pathways with improved selectivity, activity, and catalyst stability. However, designing an optimal catalyst still requires a fundamental understanding of the underlying plasmonic mechanisms at the spatial scales of single particles, at the temporal scales of electron transfer, and in conditions analogous to those under which real reactions will operate. Thus, in this review, we provide an overview of several of the available and developing nanoscale and ultrafast experimental approaches, emphasizing those that can be performed in situ. Specifically, we discuss high spatial resolution optical, tip-based, and electron microscopy techniques; high temporal resolution optical and x-ray techniques; and emerging ultrafast optical, x-ray, tip-based, and electron microscopy techniques that simultaneously achieve high spatial and temporal resolution. Ab initio and classical continuum theoretical models play an essential role in guiding and interpreting experimental exploration, and thus, these are also reviewed and several notable theoretical insights are discussed.
more » « less- Award ID(s):
- 2413590
- PAR ID:
- 10532651
- Publisher / Repository:
- AIP Publishing
- Date Published:
- Journal Name:
- Chemical Physics Reviews
- Volume:
- 4
- Issue:
- 4
- ISSN:
- 2688-4070
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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We report a transient plasmonic spin skyrmion topological quasiparticle within surface plasmon polariton vortices, which is described by analytical modeling and imaging of its formation by ultrafast interferometric time-resolved photoemission electron microscopy. Our model finds a twisted skyrmion spin texture on the vacuum side of a metal/vacuum interface and its integral opposite counterpart in the metal side. The skyrmion pair forming a hedgehog texture is associated with co-gyrating anti-parallel electric and magnetic fields, which form intense pseudoscalar E·B focus that breaks the local time-reversal symmetry and can drive magnetoelectric responses of interest to the axion physics. Through nonlinear two-photon photoemission, we record attosecond precision images of the plasmonic vectorial vortex field evolution with nanometer spatial and femtosecond temporal (nanofemto) resolution, from which we derive the twisted plasmonic spin skyrmion topological textures, their boundary, and topological charges; the modeling and experimental measurements establish a quantized integer photonic topological charge that is stable over the optical generation pulse envelope.
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Interfacial reactions drive all elemental cycling on Earth and play pivotal roles in human activities such as agriculture, water purification, energy production and storage, environmental contaminant remediation, and nuclear waste repository management. The onset of the 21st century marked the beginning of a more detailed understanding of mineral aqueous interfaces enabled by advances in techniques that use tunable high-flux focused ultrafast laser and X-ray sources to provide near-atomic measurement resolution, as well as by nano-fabrication approaches that enable transmission electron microscopy in a liquid cell. This leap into atomic- and nm-scale measurements has uncovered scale-dependent phenomena whose reaction thermodynamics, kinetics, and pathways deviate from previous observations made on larger systems. A second key advance is new experimental evidence for what scientists hypothesized but could not test previously: Namely, interfacial chemical reactions are frequently driven by “anomalies” or “non-idealities”, such as defects, nanoconfinement, and other non-typical chemical structures. Third, progress in computational chemistry have yielded new insights that allow a move beyond simple schematics leading to a molecular model of these complex interfaces. In combination with surface-sensitive measurements, we have gained knowledge of the interfacial structure and dynamics, including the underlying solid surface and the immediately adjacent water and aqueous ions, enabling a better definition of what constitutes the oxide- and silicate-water interfaces. This critical review discusses how science progresses from understanding ideal solid-water interfaces to more realistic systems, focusing on accomplishments in the last 20 years and identifying challenges and future opportunities for the community to address. We anticipate that the next 20 years will focus on understanding and predicting dynamic transient and reactive structures over greater spatial and temporal ranges, as well as systems of greater structural and chemical complexity. Closer collaborations of theoretical and experimental experts across disciplines will continue to be critical to achieving this great aspiration.more » « less
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Nickel-palladium bimetallic nanoparticles supported on multi-walled carbon nanotubes (Ni-Pd/MWCNTs) were prepared by dry mixing of the nickel and palladium salts using the mechanical energy of a ball-mill. These nanoparticles demonstrated remarkable catalytic activity in Sonogashira cross-coupling reactions with a wide range of functionalized aryl halides and terminal alkynes under ligand and copper free conditions using Monowave 50 heating reactor. The catalyst is air-stable and can be easily removed from the reaction mixture by centrifugation and reused several times with minimal loss of catalytic activity. Furthermore, the concentration of catalyst in Sonogashira reactions can be lowered to a minimum amount of 0.01 mol%while still providing a high conversion of the Sonogashira product with an excellent turnover number (TON) of 7200 and turnover frequency (TOF) of 21600 h. The Ni-Pd/MWCNTs nanoparticles were fully characterized by a variety of spectroscopic techniques including X-ray diffraction (XRD), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy (XPS). The remarkable reactivity of the Ni-Pd/MWCNTs catalyst toward Sonogashira cross-coupling reactions is attributed to the high degree of the dispersion of Ni-Pdnanoparticles with small particle size of 5-10 nm due to an efficient grinding method. This work provides a facile, solventless and inexpensive method for large-scale preparation of Ni-Pd/MWCNTs to accomplish often-challenging Sonogashira cross-coupling reactions.more » « less
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Nickel-palladium bimetallic nanoparticles supported on multi-walled carbon nanotubes (Ni-Pd/MWCNTs) were prepared by dry mixing of the nickel and palladium salts using the mechanical energy of a ball-mill. These nanoparticles demonstrated remarkable catalytic activity in Sonogashira cross-coupling reactions with a wide range of functionalized aryl halides and terminal alkynes under ligand and copper free conditions using Monowave 50 heating reactor. The catalyst is air-stable and can be easily removed from the reaction mixture by centrifugation and reused several times with minimal loss of catalytic activity. Furthermore, the concentration of catalyst in Sonogashira reactions can be lowered to a minimum amount of 0.01 mol%while still providing a high conversion of the Sonogashira product with an excellent turnover number (TON) of 7200 and turnover frequency (TOF) of 21600 h. The Ni-Pd/MWCNTs nanoparticles were fully characterized by a variety of spectroscopic techniques including X-ray diffraction (XRD), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy (XPS). The remarkable reactivity of the Ni-Pd/MWCNTs catalyst toward Sonogashira cross-coupling reactions is attributed to the high degree of the dispersion of Ni-Pdnanoparticles with small particle size of 5-10 nm due to an efficient grinding method. This work provides a facile, solventless and inexpensive method for large-scale preparation of Ni-Pd/MWCNTs to accomplish often-challenging Sonogashira cross coupling reactions.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1063/5.0163354
