Publications
121 results found
Moretti GQ, Tittl A, Cortes E, et al., 2022, Introducing a Symmetry-Breaking Coupler into a Dielectric Metasurface Enables Robust High-Q Quasi-BICs, ADVANCED PHOTONICS RESEARCH, Vol: 3, ISSN: 2699-9293
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- Citations: 1
Mancini A, Nan L, Wendisch FJ, et al., 2022, Near-Field Retrieval of the Surface Phonon Polariton Dispersion in Free-Standing Silicon Carbide Thin Films, ACS PHOTONICS, Vol: 9, Pages: 3696-3704, ISSN: 2330-4022
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- Citations: 2
Cai C, Liu B, Liu K, et al., 2022, Heteroatoms Induce Localization of the Electric Field and Promote a Wide Potential-Window Selectivity Towards CO in the CO2 Electroreduction., Angew Chem Int Ed Engl, Vol: 61
Carbon dioxide electroreduction (CO2 RR) is a sustainable way of producing carbon-neutral fuels. Product selectivity in CO2 RR is regulated by the adsorption energy of reaction-intermediates. Here, we employ differential phase contrast-scanning transmission electron microscopy (DPC-STEM) to demonstrate that Sn heteroatoms on a Ag catalyst generate very strong and atomically localized electric fields. In situ attenuated total reflection infrared spectroscopy (ATR-IR) results verified that the localized electric field enhances the adsorption of *COOH, thus favoring the production of CO during CO2 RR. The Ag/Sn catalyst exhibits an approximately 100 % CO selectivity at a very wide range of potentials (from -0.5 to -1.1 V, versus reversible hydrogen electrode), and with a remarkably high energy efficiency (EE) of 76.1 %.
Wang Q, Liu K, Hu K, et al., 2022, Attenuating metal-substrate conjugation in atomically dispersed nickel catalysts for electroreduction of CO2 to CO., Nat Commun, Vol: 13
Atomically dispersed transition metals on carbon-based aromatic substrates are an emerging class of electrocatalysts for the electroreduction of CO2. However, electron delocalization of the metal site with the carbon support via d-π conjugation strongly hinders CO2 activation at the active metal centers. Herein, we introduce a strategy to attenuate the d-π conjugation at single Ni atomic sites by functionalizing the support with cyano moieties. In situ attenuated total reflection infrared spectroscopy and theoretical calculations demonstrate that this strategy increases the electron density around the metal centers and facilitates CO2 activation. As a result, for the electroreduction of CO2 to CO in aqueous KHCO3 electrolyte, the cyano-modified catalyst exhibits a turnover frequency of ~22,000 per hour at -1.178 V versus the reversible hydrogen electrode (RHE) and maintains a Faradaic efficiency (FE) above 90% even with a CO2 concentration of only 30% in an H-type cell. In a flow cell under pure CO2 at -0.93 V versus RHE the cyano-modified catalyst enables a current density of -300 mA/cm2 with a FE above 90%.
Herran M, Sousa-Castillo A, Fan C, et al., 2022, Tailoring Plasmonic Bimetallic Nanocatalysts Toward Sunlight-Driven H<sub>2</sub> Production, ADVANCED FUNCTIONAL MATERIALS, Vol: 32, ISSN: 1616-301X
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- Citations: 16
Chen S, Luo T, Li X, et al., 2022, Identification of the Highly Active Co-N<sub>4</sub> Coordination Motif for Selective Oxygen Reduction to Hydrogen Peroxide, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 144, Pages: 14505-14516, ISSN: 0002-7863
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- Citations: 81
Hu H, Weber T, Bienek O, et al., 2022, Catalytic metasurfaces empowered by bound states in the continuum, ACS Nano, Vol: 16, Pages: 13057-13068, ISSN: 1936-0851
Photocatalytic platforms based on ultrathin reactive materials facilitate carrier transport and extraction but are typically restricted to a narrow set of materials and spectral operating ranges due to limited absorption and poor energy-tuning possibilities. Metasurfaces, a class of 2D artificial materials based on the electromagnetic design of nanophotonic resonators, allow optical absorption engineering for a wide range of materials. Moreover, tailored resonances in nanostructured materials enable strong absorption enhancement and thus carrier multiplication. Here, we develop an ultrathin catalytic metasurface platform that leverages the combination of loss-engineered substoichiometric titanium oxide (TiO2–x) and the emerging physical concept of optical bound states in the continuum (BICs) to boost photocatalytic activity and provide broad spectral tunability. We demonstrate that our platform reaches the condition of critical light coupling in a TiO2–x BIC metasurface, thus providing a general framework for maximizing light–matter interactions in diverse photocatalytic materials. This approach can avoid the long-standing drawbacks of many naturally occurring semiconductor-based ultrathin films applied in photocatalysis, such as poor spectral tunability and limited absorption manipulation. Our results are broadly applicable to fields beyond photocatalysis, including photovoltaics and photodetectors.
Yao K, Li J, Wang H, et al., 2022, Mechanistic insights into OC-COH coupling in CO2 electroreduction on fragmented copper, Journal of the American Chemical Society, Vol: 144, Pages: 14005-14011, ISSN: 0002-7863
The carbon–carbon (C–C) bond formation is essential for the electroconversion of CO2 into high-energy-density C2+ products, and the precise coupling pathways remain controversial. Although recent computational investigations have proposed that the OC–COH coupling pathway is more favorable in specific reaction conditions than the well-known CO dimerization pathway, the experimental evidence is still lacking, partly due to the separated catalyst design and mechanistic/spectroscopic exploration. Here, we employ density functional theory calculations to show that on low-coordinated copper sites, the *CO bindings are strengthened, and the adsorbed *CO coupling with their hydrogenation species, *COH, receives precedence over CO dimerization. Experimentally, we construct a fragmented Cu catalyst with abundant low-coordinated sites, exhibiting a 77.8% Faradaic efficiency for C2+ products at 300 mA cm–2. With a suite of in situ spectroscopic studies, we capture an *OCCOH intermediate on the fragmented Cu surfaces, providing direct evidence to support the OC–COH coupling pathway. The mechanistic insights of this research elucidate how to design materials in favor of OC–COH coupling toward efficient C2+ production from CO2 reduction.
Chen Q, Liu K, Zhou Y, et al., 2022, Ordered Ag Nanoneedle Arrays with Enhanced Electrocatalytic CO<sub>2</sub> Reduction via Structure-Induced Inhibition of Hydrogen Evolution, NANO LETTERS, Vol: 22, Pages: 6276-6284, ISSN: 1530-6984
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- Citations: 19
Stefancu A, Nan L, Zhu L, et al., 2022, Controlling Plasmonic Chemistry Pathways through Specific Ion Effects, ADVANCED OPTICAL MATERIALS, Vol: 10, ISSN: 2195-1071
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- Citations: 8
Cortes E, Wendisch FJ, Sortino L, et al., 2022, Optical Metasurfaces for Energy Conversion, CHEMICAL REVIEWS, ISSN: 0009-2665
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- Citations: 30
Rosenberger P, Dagar R, Zhang W, et al., 2022, Imaging elliptically polarized infrared near-fields on nanoparticles by strong-field dissociation of functional surface groups, European Physical Journal D: Atomic, Molecular, Optical and Plasma Physics, Vol: 76, Pages: 1-9, ISSN: 0011-4626
We investigate the strong-field ion emission from the surface of isolated silica nanoparticles aerosolized from an alcoholic solution, and demonstrate the applicability of the recently reported near-field imaging at 720 nm [Rupp et al., Nat. Comm., 10(1):4655, 2019] to longer wavelength (2 μm) and polarizations with arbitrary ellipticity. Based on the experimental observations, we discuss the validity of a previously introduced semi-classical model, which is based on near-field driven charge generation by a Monte-Carlo approach and classical propagation. We furthermore clarify the role of the solvent in the surface composition of the nanoparticles in the interaction region. We find that upon injection of the nanoparticles into the vacuum, the alcoholic solvent evaporates on millisecond time scales, and that the generated ions originate predominantly from covalent bonds with the silica surface rather than from physisorbed solvent molecules. These findings have important implications for the development of future theoretical models of the strong-field ion emission from silica nanoparticles, and the application of near-field imaging and reaction dynamics of functional groups on isolated nanoparticles.
Zhang W, Dagar R, Rosenberger P, et al., 2022, All-optical nanoscopic spatial control of molecular reaction yields on nanoparticles, OPTICA, Vol: 9, Pages: 551-560, ISSN: 2334-2536
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- Citations: 3
Cortes E, Grzeschik R, Maier SA, et al., 2022, Experimental characterization techniques for plasmon-assisted chemistry, NATURE REVIEWS CHEMISTRY, Vol: 6, Pages: 259-274
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- Citations: 32
Chen K, Cao M, Lin Y, et al., 2022, Ligand Engineering in Nickel Phthalocyanine to Boost the Electrocatalytic Reduction of CO<inf>2</inf>, Advanced Functional Materials, Vol: 32, 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.
Yang B, Liu K, Li H, et al., 2022, Accelerating CO2 electroreduction to multicarbon products via synergistic electric-thermal field on copper nanoneedles., Journal of the American Chemical Society, Vol: 144, Pages: 3039-3049, ISSN: 0002-7863
Electrochemical CO2 reduction is a promising way to mitigate CO2 emissions and close the anthropogenic carbon cycle. Among products from CO2RR, multicarbon chemicals, such as ethylene and ethanol with high energy density, are more valuable. However, the selectivity and reaction rate of C2 production are unsatisfactory due to the sluggish thermodynamics and kinetics of C-C coupling. The electric field and thermal field have been studied and utilized to promote catalytic reactions, as they can regulate the thermodynamic and kinetic barriers of reactions. Either raising the potential or heating the electrolyte can enhance C-C coupling, but these come at the cost of increasing side reactions, such as the hydrogen evolution reaction. Here, we present a generic strategy to enhance the local electric field and temperature simultaneously and dramatically improve the electric-thermal synergy desired in electrocatalysis. A conformal coating of ∼5 nm of polytetrafluoroethylene significantly improves the catalytic ability of copper nanoneedles (∼7-fold electric field and ∼40 K temperature enhancement at the tips compared with bare copper nanoneedles experimentally), resulting in an improved C2 Faradaic efficiency of over 86% at a partial current density of more than 250 mA cm-2 and a record-high C2 turnover frequency of 11.5 ± 0.3 s-1 Cu site-1. Combined with its low cost and scalability, the electric-thermal strategy for a state-of-the-art catalyst not only offers new insight into improving activity and selectivity of value-added C2 products as we demonstrated but also inspires advances in efficiency and/or selectivity of other valuable electro-/photocatalysis such as hydrogen evolution, nitrogen reduction, and hydrogen peroxide electrosynthesis.
Zhou Y, Liang Y, Fu J, et al., 2022, Vertical cu nanoneedle arrays enhance the local electric field promoting C2 hydrocarbons in the CO2 electroreduction, Nano Letters: a journal dedicated to nanoscience and nanotechnology, Vol: 22, Pages: 1963-1970, ISSN: 1530-6984
Electrocatalytic reduction of CO2 to multicarbon products is a potential strategy to solve the energy crisis while achieving carbon neutrality. To improve the efficiency of multicarbon products in Cu-based catalysts, optimizing the *CO adsorption and reducing the energy barrier for carbon-carbon (C-C) coupling are essential features. In this work, a strong local electric field is obtained by regulating the arrangement of Cu nanoneedle arrays (CuNNAs). CO2 reduction performance tests indicate that an ordered nanoneedle array reaches a 59% Faraday efficiency for multicarbon products (FEC2) at -1.2 V (vs RHE), compared to a FEC2 of 20% for a disordered nanoneedle array (CuNNs). As such, the very high and local electric fields achieved by an ordered Cu nanoneedle array leads to the accumulation of K+ ions, which benefit both *CO adsorption and C-C coupling. Our results contribute to the design of highly efficient catalysts for multicarbon products.
Ezendam S, Herran M, Nan L, et al., 2022, Hybrid plasmonic nanomaterials for hydrogen generation and carbon dioxide reduction, ACS Energy Letters, Vol: 7, Pages: 778-815, ISSN: 2380-8195
The successful development of artificial photosynthesis requires finding new materials able to efficiently harvest sunlight and catalyze hydrogen generation and carbon dioxide reduction reactions. Plasmonic nanoparticles are promising candidates for these tasks, due to their ability to confine solar energy into molecular regions. Here, we review recent developments in hybrid plasmonic photocatalysis, including the combination of plasmonic nanomaterials with catalytic metals, semiconductors, perovskites, 2D materials, metal–organic frameworks, and electrochemical cells. We perform a quantitative comparison of the demonstrated activity and selectivity of these materials for solar fuel generation in the liquid phase. In this way, we critically assess the state-of-the-art of hybrid plasmonic photocatalysts for solar fuel production, allowing its benchmarking against other existing heterogeneous catalysts. Our analysis allows the identification of the best performing plasmonic systems, useful to design a new generation of plasmonic catalysts.
Stefancu A, Biro OM, Todor-Boer O, et al., 2022, Halide-metal complexes at plasmonic interfaces create new decay pathways for plasmons and excited molecules, ACS Photonics, Vol: 9, Pages: 895-904, ISSN: 2330-4022
We show that by modifying the chemical interface of silver nanoparticles (AgNPs) with halide ions, it is possible to tune the total decay rate of adsorbed excited molecules and the plasmon damping rate. Through single-molecule surface-enhanced Raman scattering and surface-enhanced fluorescence enhancement factors of crystal violet (CV) and rhodamine 6G (R6G), we show that I–-modified AgNPs (AgNPs@I) and Br–-modified AgNPs (AgNPs@Br) lead to an increase in the total decay rate of excited CV and R6G by a factor between ∼1.6–2.6, compared to Cl–-modified AgNPs (AgNPs@Cl). In addition, we found that the chemical interface damping, which characterizes the plasmon resonance decay into surface states, is stronger on AgNPs@I and AgNPs@Br when compared to AgNPs@Cl. These results point toward the formation of metal–halide surface complexes. These new interfacial states can accept electrons from both excited molecular orbitals and surface plasmon excitations, completely altering the electronic dynamics and reactivity of plasmonic interfaces.
Cai C, Liu K, Zhu Y, et al., 2022, Optimizing hydrogen binding on Ru sites with RuCo alloy nanosheets for efficient alkaline hydrogen evolution, Angewandte Chemie International Edition, Vol: 61, Pages: e202113664-e202113664, ISSN: 1433-7851
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.
Violi IL, Martinez LP, Barella M, et al., 2022, Challenges on optical printing of colloidal nanoparticles, Journal of Chemical Physics, Vol: 156, ISSN: 0021-9606
While colloidal chemistry provides ways to obtain a great variety of nanoparticles with different shapes, sizes, material compositions, and surface functions, their controlled deposition and combination on arbitrary positions of substrates remain a considerable challenge. Over the last ten years, optical printing arose as a versatile method to achieve this purpose for different kinds of nanoparticles. In this article, we review the state of the art of optical printing of single nanoparticles and discuss its strengths, limitations, and future perspectives by focusing on four main challenges: printing accuracy, resolution, selectivity, and nanoparticle photostability
Besteiro L, Movsesyan A, Avalos-Ovando O, et al., 2021, Local Growth Mediated by Plasmonic Hot Carriers: Chirality from Achiral Nanocrystals Using Circularly Polarized Light, NANO LETTERS, Vol: 21, Pages: 10315-10324, ISSN: 1530-6984
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- Citations: 21
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
Optical resonances arising from quasi-bound states in the continuum (QBICs) have been recently identified in nanostructured dielectrics, showing ultrahigh quality factors accompanied by very large electromagnetic field enhancements. In this work, we design a periodic array of gallium phosphide (GaP) elliptical cylinders supporting, concurrently, three spectrally separated QBIC resonances with in-plane magnetic dipole, out-of-plane magnetic dipole, and electric quadrupole characters. We numerically explore this system for second-harmonic generation and degenerate four-wave mixing, demonstrating giant per unit cell conversion efficiencies of up to ∼ 2 W−1 and ∼ 60 W−2, respectively, when considering realistic introduced asymmetries in the metasurface, compatible with current fabrication limitations. We find that this configuration outperforms by up to more than four orders of magnitude the response of low-Q Mie or anapole resonances in individual GaP nanoantennas with engineered nonlinear mode-matching conditions. Benefiting from the straight-oriented electric field of one of the examined high-Q resonances, we further propose a novel nanocavity design for enhanced spectroscopies by slotting the meta-atoms of the periodic array. We discover that the optical cavity sustains high-intensity fields homogeneously distributed inside the slot, delivering its best performance when the elliptical cylinders are cut from end to end forming a gap, which represents a convenient model for experimental investigations. When placing an electric point dipole inside the added aperture, we find that the metasurface offers ultrahigh radiative enhancements, exceeding the previously reported slotted dielectric nanodisk at the anapole excitation by more than two orders of magnitude.
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
Even in ultralow quantities, oxygen vacancies (VO) drastically impact keyproperties of metal oxide semiconductors, such as charge transport, surface adsorption,and reactivity, playing central roles in functional materials performance. Currentmethods used to investigate VO often rely on specialized instrumentation under far fromideal reaction conditions. Hence, the influence of VO generated in situ during catalyticprocesses has yet to be probed. In this work, we assess in situ extrinsic surface VOformation and lifetime under photocatalytic conditions which we compare tophotocatalytic performance. We show for the first time that lifetimes of in situ generatedatomic VO play more significant roles in catalysis than their concentration, with strongcorrelations between longer-lived VO and higher photocatalytic activity. Our resultsindicate that enhanced photocatalytic efficiency correlates with goldilocks VOconcentrations, where VO densities must be just right to encourage carrier transportwhile avoiding charge carrier trapping.
Huettenhofer L, Golibrzuch M, Bienek O, et al., 2021, Metasurface photoelectrodes for enhanced solar fuel generation, Advanced Energy Materials, Vol: 11, ISSN: 1614-6832
Tailoring optical properties in photocatalysts by nanostructuring them can help increase solar light harvesting efficiencies in a wide range of materials. Whereas plasmon resonances are widely employed in metallic catalysts for this purpose, latest advances of nonradiative, dielectric nanophotonics also enable light confinement and enhanced visible light absorption in semiconductors. Here, a design procedure for large-scale nanofabrication of semiconductor photoelectrodes using imprint lithography is developed. Anapole excitations and metasurface lattice resonances are combined to enhance the absorption of the model material, amorphous gallium phosphide (a-GaP), over the visible spectrum. It is shown that cost-effective, high sample throughput is achieved while retaining the precise signature of the engineered photonic states. Photoelectrochemical measurements under hydrogen evolution reaction conditions and sunlight illumination reveal the contributions of the respective resonances and demonstrate an overall photocurrent enhancement of 5.7, compared to a planar film. These results are supported by optical and numerical analysis of single nanodisks and of the upscaled metasurface.https://onlinelibrary.wiley.com/doi/10.1002/aenm.202102877
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: a journal dedicated to nanoscience and nanotechnology, Vol: 21, Pages: 8348-8354, ISSN: 1530-6984
Metal-oxide semiconductors (MOS) are widely utilized for catalytic and photocatalytic applications in which the dynamics of charged carriers (e.g., electrons, holes) play important roles. Under operation conditions, photoinduced surface oxygen vacancies (PI-SOV) can greatly impact the dynamics of charge carriers. However, current knowledge regarding the effect of PI-SOV on the dynamics of hole migration in MOS films, such as titanium dioxide, is solely based upon volume-averaged measurements and/or vacuum conditions. This limits the basic understanding of hole-vacancy interactions, as they are not capable of revealing time-resolved variations during operation. Here, we measured the effect of PI-SOV on the dynamics of hole migration using time-resolved atomic force microscopy. Our findings demonstrate that the time constant associated with hole migration is strongly affected by PI-SOV, in a reversible manner. These results will nucleate an insightful understanding of the physics of hole dynamics and thus enable emerging technologies, facilitated by engineering hole-vacancy interactions.
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
We report the mechanism of rhodamine B (RhB) acting as an electrolyte additive in Li/graphite cells. We show that the cycle performance and rate capability of graphite are enhanced in carbonate-based electrolytes containing 0.2 wt% RhB. By using silica-encapsulated Au nanoparticles, in situ surface-enhanced Raman spectroscopy (SERS) is applied to study the graphite/electrolyte interface. We find that the adsorption orientation of RhB molecules on the surface of graphite can be modulated by the applied potential: vertical adsorption at higher potentials while horizontal adsorption takes place at lower potentials. This behavior effectively suppresses the electrolyte solvent decomposition, as well as electrode corrosion while improving the Li+ diffusion. This work shows that SERS is a powerful tool for interfacial analysis of battery systems and provides new ideas for rational design of electrolyte additives.
Stefancu A, Lee S, Zhu L, et al., 2021, Fermi level equilibration at the metal-molecule interface in plasmonic systems, Nano Letters: a journal dedicated to nanoscience and nanotechnology, Vol: 21, Pages: 6592-6599, ISSN: 1530-6984
We highlight a new metal–molecule charge transfer process by tuning the Fermi energy of plasmonic silver nanoparticles (AgNPs) in situ. The strong adsorption of halide ions upshifts the Fermi level of AgNPs by up to ∼0.3 eV in the order Cl– < Br– < I–, favoring the spontaneous charge transfer to aligned molecular acceptor orbitals until charge neutrality across the interface is achieved. By carefully quantifying, experimentally and theoretically, the Fermi level upshift, we show for the first time that this effect is comparable in energy to different plasmonic effects such as the plasmoelectric effect or hot-carriers production. Moreover, by monitoring in situ the adsorption dynamic of halide ions in different AgNP–molecule systems, we show for the first time that the catalytic role of halide ions in plasmonic nanostructures depends on the surface affinity of halide ions compared to that of the target molecule.
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.
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