73 results found
Besteiro LV, Movsesyan A, Ávalos-Ovando O, et al., 2021, Local Growth Mediated by Plasmonic Hot Carriers: Chirality from Achiral Nanocrystals Using Circularly Polarized Light., Nano Lett, Vol: 21, Pages: 10315-10324
Plasmonic nanocrystals and their assemblies are excellent tools to create functional systems, including systems with strong chiral optical responses. Here we study the possibility of growing chiral plasmonic nanocrystals from strictly nonchiral seeds of different types by using circularly polarized light as the chirality-inducing mechanism. We present a novel theoretical methodology that simulates realistic nonlinear and inhomogeneous photogrowth processes in plasmonic nanocrystals, mediated by the excitation of hot carriers that can drive surface chemistry. We show the strongly anisotropic and chiral growth of oriented nanocrystals with lowered symmetry, with the striking feature that such chiral growth can appear even for nanocrystals with subwavelength sizes. Furthermore, we show that the chiral growth of nanocrystals in solution is fundamentally challenging. This work explores new ways of growing monolithic chiral plasmonic nanostructures and can be useful for the development of plasmonic photocatalysis and fabrication technologies.
Glass D, Quesada-Cabrera R, Bardey S, et al., 2021, Probing the Role of Atomic Defects in Photocatalytic Systems through Photoinduced Enhanced Raman Scattering, ACS ENERGY LETTERS, Vol: 6, Pages: 4273-4281, ISSN: 2380-8195
Moretti GQ, Cortes E, Maier SA, et al., 2021, Engineering gallium phosphide nanostructures for efficient nonlinear photonics and enhanced spectroscopies, NANOPHOTONICS, Vol: 10, Pages: 4261-4271, ISSN: 2192-8606
Cai C, Liu K, Zhu Y, et al., 2021, Optimizing Hydrogen Binding on Ru Sites with RuCo Alloy Nanosheets for Efficient Alkaline Hydrogen Evolution., Angew Chem Int Ed Engl
Ruthenium (Ru)-based catalysts, with considerable performance and desirable cost, are becoming highly interesting candidates to replace platinum (Pt) in the alkaline hydrogen evolution reaction (HER). The hydrogen binding at Ru sites (Ru-H) is an important factor limiting the HER activity. Herein, density functional theory (DFT) simulations show that the essence of Ru-H binding energy is the strong interaction between the 4 d z 2 orbital of Ru and the 1s orbital of H. The charge transfer between Ru sites and substrates (Co and Ni) causes the appropriate downward shift of the 4 d z 2 -band center of Ru, which results in a Gibbs free energy of 0.022 eV for H* in the RuCo system, much lower than the 0.133 eV in the pure Ru system. This theoretical prediction has been experimentally confirmed using RuCo alloy-nanosheets (RuCo ANSs). They were prepared via a fast co-precipitation method followed with a mild electrochemical reduction. Structure characterizations reveal that the Ru atoms are embedded into the Co substrate as isolated active sites with a planar symmetric and Z-direction asymmetric coordination structure, obtaining an optimal 4 d z 2 modulated electronic structure. Hydrogen sensor and temperature program desorption (TPD) tests demonstrate the enhanced Ru-H interactions in RuCo ANSs compared to those in pure Ru nanoparticles. As a result, the RuCo ANSs reach an ultra-low overpotential of 10 mV at 10 mA cm-2 and a Tafel slope of 20.6 mV dec-1 in 1 M KOH, outperforming that of the commercial Pt/C. This holistic work provides a new insight to promote alkaline HER by optimizing the metal-H binding energy of active sites.
Huettenhofer L, Golibrzuch M, Bienek O, et al., 2021, Metasurface Photoelectrodes for Enhanced Solar Fuel Generation, ADVANCED ENERGY MATERIALS, Vol: 11, ISSN: 1614-6832
Poblet M, Berte R, Boggiano HD, et al., 2021, Acoustic coupling between plasmonic nanoantennas: detection and directionality of surface acoustic waves, ACS Photonics, Vol: 8, Pages: 2846-2852, ISSN: 2330-4022
Hypersound waves can be efficient mediators between optical signals at the nanoscale. Having phase velocities several orders of magnitude lower than the speed of light, they propagate with much shorter wavelengths and can be controlled, directed, and even focused in a very small region of space. This work shows how two optical nanoantennas can be coupled through an acoustic wave that propagates with a certain directionality. An “emitter” antenna is first optically excited to generate acoustic coherent phonons that launch surface acoustic waves through the underlying substrate. These waves travel until they are mechanically detected by a “receiver” nanoantenna whose oscillation produces a detectable optical signal. Generation and detection are studied in detail, and new designs are proposed to improve the directionality of the hypersonic surface acoustic wave.
Dagdeviren OE, Glass D, Sapienza R, et al., 2021, The Effect of Photoinduced Surface Oxygen Vacancies on the Charge Carrier Dynamics in TiO2 Films, NANO LETTERS, Vol: 21, Pages: 8348-8354, ISSN: 1530-6984
Stefancu A, Lee S, Zhu L, et al., 2021, Fermi Level Equilibration at the Metal-Molecule Interface in Plasmonic Systems, NANO LETTERS, Vol: 21, Pages: 6592-6599, ISSN: 1530-6984
Zhu C, Fan C, Cortes E, et al., 2021, In situ surface-enhanced Raman spectroelectrochemistry reveals the molecular conformation of electrolyte additives in Li-ion batteries, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 9, Pages: 20024-20031, ISSN: 2050-7488
Wang X, Liu C, Gao C, et al., 2021, Self-constructed multiple plasmonic hotspots on an individual fractal to amplify broadband hot electron generation., ACS Nano, Vol: 15, Pages: 10553-10564, ISSN: 1936-0851
Plasmonic nanoparticles are ideal candidates for hot-electron-assisted applications, but their narrow resonance region and limited hotspot number hindered the energy utilization of broadband solar energy. Inspired by tree branches, we designed and chemically synthesized silver fractals, which enable self-constructed hotspots and multiple plasmonic resonances, extending the broadband generation of hot electrons for better matching with the solar radiation spectrum. We directly revealed the plasmonic origin, the spatial distribution, and the decay dynamics of hot electrons on the single-particle level by using ab initio simulation, dark-field spectroscopy, pump-probe measurements, and electron energy loss spectroscopy. Our results show that fractals with acute tips and narrow gaps can support broadband resonances (400-1100 nm) and a large number of randomly distributed hotspots, which can provide unpolarized enhanced near field and promote hot electron generation. As a proof-of-concept, hot-electron-triggered dimerization of p-nitropthiophenol and hydrogen production are investigated under various irradiations, and the promoted hot electron generation on fractals was confirmed with significantly improved efficiency.
Hüttenhofer L, Tittl A, Kühner L, et al., 2021, Anapole-assisted absorption engineering in arrays of coupled amorphous gallium phosphide nanodisks, ACS Photonics, Vol: 8, Pages: 1469-1476, ISSN: 2330-4022
Broadband solar light harvesting plays a crucial role for efficient energy conversion. Anapole excitations and associated absorption engineering in dielectric nanoresonators are a focus of nanophotonic research due to the intricate combination of nonradiating modes and strong electromagnetic field confinement in the underlying material. The arising high field strengths are used for enhanced second-harmonic generation and photocatalysis, where devices require large areas with closely spaced nanoresonators for sizable photonic yields. However, most anapole studies have so far been carried out at the single-particle level, neglecting the influence of anapole–anapole interactions. Here, we present a systematic study of coupling mechanisms in rectangular arrays of amorphous GaP nanodisks that support anapole excitations at 600 nm, which is within the lossy spectral regime of the material. Our experimental findings show that maximum visible light extinction by the array and maximum absorption in the GaP are not achieved by the densest packing of resonators. Counterintuitively, increasing the array periodicities such that collective effects spectrally overlap with the anapole excitation of a single particle leads to an absorption enhancement of up to 300% compared to a single disk. An analysis of coupling in one- and two-dimensional arrays with polarization-dependent measurements and numerical simulations allows us to discriminate between coupling interactions parallel and perpendicular to the polarization axis and evaluate their strengths. Utilizing a multipolar decomposition of excitations in single nanodisks embedded in one-dimensional arrays, we can attribute the coupling to enhanced electric and toroidal dipoles under variation of the interparticle spacing. Our results provide a fundamental understanding of tailored light absorption in coupled anapole resonators and reveal important design guidelines for advanced metasurface approaches in a wide range of energy
Li H, Liu K, Fu J, et al., 2021, Paired Ru-O-Mo ensemble for efficient and stable alkaline hydrogen evolution reaction, NANO ENERGY, Vol: 82, ISSN: 2211-2855
Barella M, Violi IL, Gargiulo J, et al., 2021, In Situ Photothermal Response of Single Gold Nanoparticles through Hyperspectral Imaging Anti-Stokes Thermometry, ACS NANO, Vol: 15, Pages: 2458-2467, ISSN: 1936-0851
Chen K, Cao M, Lin Y, et al., 2021, Ligand Engineering in Nickel Phthalocyanine to Boost the Electrocatalytic Reduction of CO<inf>2</inf>, Advanced Functional Materials, ISSN: 1616-301X
Designing and synthesizing efficient molecular catalysts may unlock the great challenge of controlling the CO2 reduction reaction (CO2RR) with molecular precision. Nickel phthalocyanine (NiPc) appears as a promising candidate for this task due to its adjustable Ni active-site. However, the pristine NiPc suffers from poor activity and stability for CO2RR owing to the poor CO2 adsorption and activation at the bare Ni site. Here, a ligand-tuned strategy is developed to enhance the catalytic performance and unveil the ligand effect of NiPc on CO2RR. Theoretical calculations and experimental results indicate that NiPc with electron-donating substituents (hydroxyl or amino) can induce electronic localization at the Ni site which greatly enhances the CO2 adsorption and activation. Employing the optimal catalyst—an amino-substituted NiPc—to convert CO2 into CO in a flow cell can achieve an ultrahigh activity and selectivity of 99.8% at current densities up to −400 mA cm−2. This work offers a novel strategy to regulate the electronic structure of active sites by ligand design and discloses the ligand-directed catalysis of the tailored NiPc for highly efficient CO2RR.
Lee JB, Walker H, Li Y, et al., 2020, Template Dissolution Interfacial Patterning of Single Colloids for Nanoelectrochemistry and Nanosensing, ACS NANO, Vol: 14, Pages: 17693-17703, ISSN: 1936-0851
Lee S, Hwang H, Lee W, et al., 2020, Core-Shell Bimetallic Nanoparticle Trimers for Efficient Light-to-Chemical Energy Conversion, ACS ENERGY LETTERS, Vol: 5, Pages: 3881-3890, ISSN: 2380-8195
Tilmann B, Grinblat G, Berte R, et al., 2020, Nanostructured amorphous gallium phosphide on silica for nonlinear and ultrafast nanophotonics, NANOSCALE HORIZONS, Vol: 5, Pages: 1500-1508, ISSN: 2055-6756
Poblet M, Li Y, Cortes E, et al., 2020, Direct Detection of Optical Forces of Magnetic Nature in Dielectric Nanoantennas, NANO LETTERS, Vol: 20, Pages: 7627-7634, ISSN: 1530-6984
Grinblat G, Zhang H, Nielsen MP, et al., 2020, Efficient ultrafast all-optical modulation in a nonlinear crystalline gallium phosphide nanodisk at the anapole excitation, SCIENCE ADVANCES, Vol: 6, ISSN: 2375-2548
Mancini A, Gubbin CR, Berte R, et al., 2020, Near-Field Spectroscopy of Cylindrical Phonon-Polariton Antennas, ACS NANO, Vol: 14, Pages: 8508-8517, ISSN: 1936-0851
Cortes E, Govorov AO, Misawa H, et al., 2020, Special topic on emerging directions in plasmonics, JOURNAL OF CHEMICAL PHYSICS, Vol: 153, ISSN: 0021-9606
Boggiano HD, Berte R, Scarpettini AF, et al., 2020, Determination of nanoscale mechanical properties of polymers via plasmonic nanoantennas, ACS Photonics, Vol: 7, Pages: 1403-1409, ISSN: 2330-4022
Nanotechnology and the consequent emergence of miniaturized devices are driving the need to improve our understanding of the mechanical properties of a myriad of materials. Here we focus on amorphous polymeric materials and introduce a new way to determine the nanoscale mechanical response of polymeric thin films in the GHz range, using ultrafast optical means. Coupling of the films to plasmonic nanoantennas excited at their vibrational eigenfrequencies allows the extraction of the values of the mechanical moduli as well as the estimation of the glass transition temperature via time-domain measurements, here demonstrated for PMMA films. This nanoscale method can be extended to the determination of mechanical and elastic properties of a wide range of spatially strongly confined materials.
Doiron B, Gusken NA, Lauri A, et al., 2020, Hot Carrier Optoelectronics with Titanium Nitride, Lasers and Electro-Optics Society Annual Meeting-LEOS, ISSN: 1092-8081
© 2020 OSA. Titanium oxynitride enables a range of plasmonic and optoelectronic functionality using long-lived photo-generated hot carriers. We explore the time scale of hot carriers in TiN and their use in photochemical reduction and Schottky detectors.
Bell SEJ, Charron G, Cortes E, et al., 2020, Towards Reliable and Quantitative Surface-Enhanced Raman Scattering (SERS): From Key Parameters to Good Analytical Practice, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 59, Pages: 5454-5462, ISSN: 1433-7851
Bell SEJ, Charron G, Cortés E, et al., 2020, Auf dem Weg zur verlässlichen und quantitativen SERS‐Spektroskopie: von Schlüsselparametern zur guten analytischen Praxis, Angewandte Chemie, Vol: 132, Pages: 5496-5505, ISSN: 0044-8249
Hüttenhofer L, Eckmann F, Lauri A, et al., 2020, Anapole excitations in oxygen vacancy-rich TiO2-x nanoresonators: tuning the absorption for photocatalysis in the visible., ACS Nano, Vol: 14, Pages: 2456-2464, ISSN: 1936-0851
Research on optically resonant dielectric nanostructures has accelerated the development of photonic applications, driven by their ability to strongly confine light on the nanoscale. However, since dielectric resonators are typically operated below their bandgap to minimize optical losses, the usage of dielectric nanoantenna concepts for absorption enhancement has largely remained unexplored. In this work, we realize engineered nanoantennas composed of photocatalytic dielectrics and demonstrate their increased light harvesting capabilities in otherwise weakly absorptive spectral regions. In particular, we employ anapole excitations, which are known for their strong light confinement, in nanodisks of oxygen-vacancy-rich TiO2-x, a prominent photocatalyst that provides a powerful platform for exploring concepts in absorption enhancement in tunable nanostructures. We show that by varying the nanodisk geometry, we can shift the anapole wavelength into resonance with optical transitions associated with the sub-bandgap oxygen vacancy (VO) states and thereby increase visible light absorption. The arising photocatalytic effect is monitored on the single particle level using the well-established photocatalytic silver reduction reaction on TiO2. With the freedom of changing the optical properties of TiO2 through tuning the abundance of VO-states we discuss the interplay between cavity damping and the anapole-assisted field confinement for absorption enhancement. This concept is general and can be extended to other catalytic materials with higher refractive indices.
Glass D, Cortes E, Peveler WJ, et al., 2020, Enhancing hybrid metal-semiconductor systems beyond SERS with PIERS (Photo-induced enhanced Raman scattering) for trace analyte detection, Conference on Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XXI held at SPIE Defense + Commercial Sensing Conference, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Glass D, Cortes E, Ben-Jaber S, et al., 2019, Dynamics of Photo-Induced Surface Oxygen Vacancies in Metal-Oxide Semiconductors Studied Under Ambient Conditions, ADVANCED SCIENCE, Vol: 6
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