Naomi J Halas

Naomi J Halas
Rice University

About

436
Publications
127,372
Reads
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85,587
Citations
Additional affiliations
January 2010 - December 2011
Independent Researcher
Independent Researcher
Position
  • Chinese Academy of Sciences
January 2010 - December 2011
Baylor College of Medicine
January 2010 - present
Harvard University

Publications

Publications (436)
Article
Plasmonic nanostructures have attracted increasing interest in the fields of photochemistry and photocatalysis for their ability to enhance reactivity and tune reaction selectivity, a benefit of their strong interactions with light and their multiple energy decay mechanisms. Here we introduce the use of earth-abundant plasmonic aluminum nanoparticl...
Article
Photoelectrochemical water splitting, as a method for producing clean hydrogen, could benefit from both plasmon-enhanced processes and the incorporation of earth-abundant materials in photoelectrode design. Here we report a n-TiO 2 / aluminum (Al) nanodisk/p-GaN photoelectrode sandwich device that exhibits enhanced H 2 generation efficiencies due t...
Article
Nanoparticle-assisted laser-induced photothermal therapy (PTT) is a promising method for cancer treatment, yet, visualization of nanoparticle uptake and photothermal response remain a critical challenge. Here we report a magnetic resonance imaging-active nanomatryoshka (Gd2O3-NM), a multilayered (Au core/Gd2O3 shell/Au shell) sub-100 nm nanoparticl...
Article
A promising clinical trial utilizing gold-silica core-shell nanostructures coated with polyethylene glycol (PEG) has been reported for near-infrared (NIR) photothermal therapy (PTT) of prostate cancer. The next critical step for PTT is the visualization of therapeutically relevant nanoshell (NS) concentrations at the tumor site. Here we report the...
Article
The synthesis of Al nanocrystals (Al NCs) is a rapidly expanding field, but there are few strategies for size and morphology control. Here we introduce a dual catalyst approach for the synthesis of Al NCs to control both NC size and shape. By using one catalyst that nucleates growth more rapidly than a second catalyst whose ligands affect NC morpho...
Article
Transitioning plasmonic metasurfaces into practical, low-cost applications requires meta-atom designs that focus on ease of manufacturability and a robustness with respect to structural imperfections and nonideal substrates. It also requires the use of inexpensive, earth-abundant metals such as Al for plasmonic properties. In this study, we focus o...
Article
Vacuum ultraviolet (VUV) light plays an essential role across science and technology, from molecular spectroscopy to nanolithography and biomedical procedures. Realizing nanoscale devices for VUV light generation and control is critical for next-generation VUV sources and systems, but the scarcity of low-loss VUV materials creates a substantial cha...
Chapter
Full-text available
On the surface of a metallic nanoparticle that supports collective electronic (plasmon) resonances, strongly enhanced optical fields, energetic electrons and/ or holes, and strong photothermal heating can be induced by optical illumination. These processes create a local environment where chemical reactions can occur with unusually high efficiencie...
Article
Clean water is critical for drinking, industrial processes, and aquatic organisms. Existing water treatment and infrastructure are chemically intensive and based on nearly century-old technologies that fail to meet modern large and decentralized communities. The next-generation of water processes can transition from outdated technologies by utilizi...
Article
Significance Photochemical processes on the surfaces of illuminated metallic nanoparticles have shown outstanding efficiencies and may provide new, light-based strategies for inducing chemical transformations that consume far less energy than do conventional heat-driven catalysts. Energetic, or “hot” electrons, play an important role in these types...
Article
Full-text available
Plasmonic nanoantennas focus light below the diffraction limit, creating strong field enhancements, typically within a nanoscale junction. Placing a nanostructure within the junction can greatly enhance the nanostructure's innate optical absorption, resulting in intense photothermal heating that could ultimately compromise both the nanostructure an...
Article
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The field of plasmonics has largely been inspired by the properties of Au and Ag nanoparticles, leading to applications in sensing, photocatalysis, nanomedicine, and solar water treatment. Recently the quest for new plasmonic materials has focused on earth-abundant elements, where aluminum is a sustainable, low-cost potential alternative. Here we r...
Article
Full-text available
ConspectusAluminum in its nanostructured form is generating increasing interest because of its light-harvesting properties, achieved by excitation of its localized surface plasmon resonance. Compared to traditional plasmonic materials, the coinage metals Au and Ag, Al is far more earth-abundant and, therefore, more suitable for large-area applicati...
Article
Collective, coherent excitations in molecules, termed molecular plasmons, can be observed in neutral and charged polycyclic aromatic hydrocarbons (PAHs). Systems in this few-atom limit show behavior strongly dependent on charge state, where the addition or removal of even a single electron dramatically alters electronic and optical properties. Here...
Article
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The shape of a plasmonic nanoparticle strongly controls its light-matter interaction, which in turn affects how specific morphologies may be used in applications such as sensing, photodetection, and active pixel displays. Here we show that particle shape also controls plasmonic photocatalytic activity. Three different Al nanocrystal morphologies: o...
Article
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Plasmonic nanowires (NWs) have generated great interest for their applications in nanophotonics and nanotechnology. Here we report the synthesis of Al nanocrystals (NCs) with controlled morphologies that range from nanospheres to branched NW and NW bundles. This is accomplished by catalyzing the pyrolysis of triisobutyl aluminum (TIBA) with Tebbe’s...
Article
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The activation of carbon–fluorine bonds is an industrially and environmentally critical, but energetically challenging, transformation. Here we demonstrate a plasmonic photocatalysis approach to visible-light-driven hydrodefluorination that utilizes aluminium–palladium antenna–reactor heterostructures. Photocatalytic hydrodefluorination of aliphati...
Article
Significance The presence of organic micropollutants, resulting from pesticide, solvent, detergent, or pharmaceutical use, in drinking water sources poses a significant threat to human health. Degrading these dangerous pollutants using advanced oxidation processes is a desirable but highly energy-intensive treatment option. Here, we report the sola...
Article
Full-text available
Photoactivation of catalytic materials through plasmon-coupled energy transfer has created new possibilities for expanding the scope of light-driven heterogeneous catalysis. Here we present a nanoengineered plasmonic photocatalyst consisting of catalytic Pd islands preferentially grown on the vertices of Al nanocubes. The regioselective Pd depositi...
Article
Acoustic vibrations in plasmonic nanoparticles, monitored by an all-optical means, have attracted significant increasing interest because they provide unique insight into the mechanical properties of these metallic nanostructures. Al nanostructures are a recently emerging alternative to noble metal nanoparticles, because their broad wavelength tuna...
Article
Full-text available
Plasmonic nanoantennas are capable of reversibly interconverting free-space radiation with localized modes at the nanoscale. However, optical access to a single nanoantenna, through a laser beam, is always accompanied by disruptive background perturbations and heating effects. Remote spectroscopy is one promising route to overcome these effects. He...
Article
Full-text available
Evaporation-based solar thermal distillation is a promising approach for purifying high-salinity water, but the liquid-vapor phase transition inherent to this process makes it intrinsically energy intensive. Here we show that the exchange of heat between the distilled and input water can fulfill a resonance condition, resulting in dramatic increase...
Article
Dimers -two closely-spaced metallic nanostructures- are one of the primary nanoscale geometries in plasmonics, supporting high local field enhancements in their interparticle junction under excitation of their hybridized “bonding” plasmon. However, when a dimer is fabricated on a metallic substrate, its characteristics are changed profoundly. Here...
Article
Full-text available
Syngas, an extremely important chemical feedstock composed of carbon monoxide and hydrogen, can be generated through methane (CH4) dry reforming with CO2. However, traditional thermocatalytic processes require high temperatures and suffer from coke-induced instability. Here, we report a plasmonic photocatalyst consisting of a Cu nanoparticle ‘anten...
Conference Paper
Nonlinear metasurface devices for generation and manipulation of coherent vacuum ultraviolet (VUV) light will be reported in this talk. The approaches for design, fabrication, and measurement of the metasurface devices with different working principles will be discussed. Our ultracompact metasurfaces are capable of efficiently generating VUV light...
Article
Dielectric metasurfaces have recently been shown to provide an excellent platform for the harmonic generation of light, due to their low optical absorption and to the strong electromagnetic field enhancement that can be designed into their constituent meta-atoms. Here, we demonstrate vacuum ultraviolet (VUV) third harmonic generation from a special...
Article
Full-text available
Biocompatible gold nanoparticles designed to absorb light at wavelengths of high tissue transparency have been of particular interest for biomedical applications. The ability of such nanoparticles to convert absorbed near-infrared light to heat and induce highly localized hyperthermia has been shown to be highly effective for photothermal cancer th...
Article
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Of the many plasmonic nanoparticle geometries that have been synthesized, nanocubes have been of particular interest for creating nanocavities, facilitating plasmon coupling, and enhancing phenomena dependent upon local electromagnetic fields. Here we report the straightforward colloidal synthesis of single-crystalline {100} terminated Al nanocubes...
Article
Photocatalysis with optically active "plasmonic" nanoparticles is a growing field in heterogeneous catalysis, with the potential for substantially increasing efficiencies and selectivities of chemical reactions. Here, the decomposition of nitrous oxide (N2O), a potent anthropogenic greenhouse gas, on illuminated aluminum-iridium (Al-Ir) antenna-rea...
Article
Full-text available
Plasmonic photocatalytic processes typically use the interaction of light with metallic nanoparticles to drive chemical reactions on their surfaces. Here we show that a plasmonic photocatalyst can also induce a reaction on an adjacent material. A combination of spontaneous H2 dissociation and plasmon-induced H desorption from tilted Palladium (Pd)...
Article
Full-text available
The ever-increasing global need for potable water requires practical, sustainable approaches for purifying abundant alternative sources such as seawater, high-salinity processed water, or underground reservoirs. Evaporation-based solutions are of particular interest for treating high salinity water, since conventional methods such as reverse osmosi...
Article
Synthetic ammonia has been the primary worldwide source of agricultural fertilizer over last century and is a promising carbon-free energy carrier for sustainable transportation. Despite its global importance, synthetic ammonia produced with the Haber-Bosch process is extremely energy and resource intensive. Here we demonstrate a three-step phototh...
Article
Developing highly efficient nanoscale coherent light sources is essential for advances in technological applications such as integrated photonic circuits, bioimaging, and sensing. An on-chip wavelength convertor based on second harmonic generation (SHG) would be a crucial step toward this goal, but the light-conversion efficiency would be low for s...
Article
Sivan et al . claim that the methods used to distinguish thermal from hot carrier effects in our recent report are inaccurate and that our data can be explained by a purely thermal mechanism with a fixed activation energy. This conclusion is invalid, because they substantially misinterpret the emissivity of the photocatalyst and assume a linear int...
Article
Full-text available
Rotational spectroscopy has been used for decades for virtually unambiguous identification of gas phase molecular species, but it has rarely been used for the quantitative analysis of molecular concentrations. Challenges have included the nontrivial reconstruction of integrated line strengths from modulated spectra, the correlation of pressure-depe...
Article
Full-text available
Aluminum nanocrystals have emerged as an earth-abundant material for plasmonics applications. Al nanocrystals readily oxidize in aqueous-based solutions, however, transforming into highly stratified γ-AlOOH nanoparticles with a 700% increase in surface area in a matter of minutes. Here we show that by functionalizing Al nanocrystals with the bio-in...
Article
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Metal-organic frameworks (MOFs) and metal nanoparticles are two classes of materials that have received considerable recent attention, each for controlling chemical reactivities, albeit in very different ways. Here, we report the growth of MOF shell layers surrounding aluminum nanocrystals (Al NCs), an Earth-abundant metal with energetic, plasmonic...
Article
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The precise size- and shape-controlled synthesis of monodisperse Al nanocrystals remains an open challenge, limiting their utility for numerous applications that would take advantage of their size and shape-dependent optical properties. Here we pursue a molecular-level understanding of the formation of Al nanocrystals by titanium(IV) isopropoxide-c...
Conference Paper
An all-dielectric metasurface device for nonlinear generation of coherent vacuum ultraviolet will be is reported. The metasurface made of ZnO has a resonance at 394 nm and can generate vacuum ultraviolet under ultrafast laser illumination.
Article
Full-text available
The harmonic generation of light with plasmonic and all-dielectric nanostructures has gained much recent interest. This approach is especially promising for short wavelength (i.e. ultraviolet (UV)) generation, where conventional nonlinear crystals reach their limits both in transparency and in their ability to achieve phase-matching between the inp...
Article
Infrared (IR) spectroscopy has been a central tool for chemical analysis for decades, useful in a wide range of fields for the detection and quantification of molecules based on their unique vibrational resonances. Conventional IR spectroscopy relies on bulky, dispersive optics, however, making portability and miniaturization a substantial challeng...
Article
Full-text available
The challenge of controllable chemical synthesis of aluminum nanocrystals (Al NCs) has been met with only limited success. A major barrier is the absence of effective ligands to control the nucleation and growth of Al NCs. Here we demonstrate the size- and shape-controlled synthesis of monodisperse Al NCs using a polymer ligand, cumyl dithiobenzoat...
Article
Full-text available
The excellent light harvesting ability of plasmonic nanoparticles makes them promising materials for a variety of technologies that rely on the conversion of photons to energetic charge carriers. In such applications, including photovoltaics and photocatalysis, the excitation of surface plasmons must induce charge transfer across the metal-adsorbat...
Article
Full-text available
Photocatalysis based on optically active, “plasmonic” metal nanoparticles has emerged as a promising approach to facilitate light-driven chemical conversions under far milder conditions than thermal catalysis. However, an understanding of the relation between thermal and electronic excitations has been lacking. We report the substantial light-induc...
Article
Full-text available
Many epoxy adhesives require high temperatures to bond composite materials. However, oven heating severely restricts what may be attached or enclosed within composite material-based structures and greatly limits the possibilities for repair. Inspired by initial reports of photothermal epoxy curing using plasmonic nanoparticles, we examine how laser...
Article
The optical reshaping of metallic nanostructures typically requires intense laser pulses to first approach or achieve melting, followed by surface-tension-dominated reshaping, transforming the original nanostructures into more spherical morphologies. Here we report the directional optical reshaping of the Au nanodisk of an Al-Au heterodimer in the...
Article
Infrared (IR) photodetection is of major scientific and technical interest since virtually all molecules exhibit characteristic vibrational modes in the mid-infrared region of the spectrum, giving rise to molecular spectroscopy and chemical imaging in this wavelength range. High-resolution IR spectroscopies, such as Fourier Transform IR spectroscop...
Article
Polycyclic aromatic hydrocarbon (PAH) molecules are essentially graphene in the subnanometer limit, typically consisting of 50 or fewer atoms. With the addition or removal of a single electron, these molecules can support molecular plasmon (collective) resonances in the visible region of the spectrum. Here, we probe the plasmon dynamics in these qu...
Article
Plasmonic hot-carrier-based photodetectors detect light at frequencies below the semiconductor bandgap with room temperature operation, and can exhibit spectrally narrowband behavior, potentially eliminating the need for bulky filtering or dispersive optics. This photodetection mechanism has, however, been plagued with low responsivities. Here we c...
Article
No other resource is as necessary for life as water, and providing it universally in a safe, reliable and affordable manner is one of the greatest challenges of the twenty-first century. Here, we consider new opportunities and approaches for the application of nanotechnology to enhance the efficiency and affordability of water treatment and wastewa...
Article
A Combined Experimental and Theoretical Approach to Measure Spatially Resolved Local Surface Plasmon Resonances in Aluminum Nanocrystals - Volume 24 Supplement - Alina Bruma, Canhui Wang, Wei-Chang D. Yang, Dayne F. Swearer, Naomi J. Halas, Renu Sharma