Honors & Awards


  • Hershel M. Rich Invention Award, George R. Brown School of Engineering; Rice University (2019)
  • Arnold O. Beckman Postdoctoral Fellowship in the Chemical Sciences, The Arnold and Mabel Beckman Foundation (2018)
  • Harry B. Weiser Leadership Award, Rice University (2017)
  • Hasselman Fellowship in Chemistry, Rice University (2017)
  • Young Scientist Ambassador for the United States, 67th Annual Lindau Noble Laureate Meeting (2017)
  • Best Poster Award, Gordon Research Conference on Noble Metal Nanoparticles (2016)
  • John J. Fannaly Nanotechnology Award, Smalley-Curl Institute (2016)
  • Stephen C. Hofmann Fellowship, Rice University (2016)
  • Graduate Research Fellowship, National Science Foundation (2015)
  • National Defense Science and Engineering Graduate Fellowship, US Department of Defense (2015)
  • Bruce O. Hutchins Award, Drexel University (2014)
  • Maryanoff Scholarship for Chemical Research, Drexel University (2013)
  • Maryanoff Summer Research Fellowship, Drexel University (2010)

Professional Education


  • Master of Science, Drexel University (2014)
  • Doctor of Philosophy, Rice University (2019)
  • Bachelor of Science, Drexel University (2014)
  • Master of Arts, Rice University (2017)

Stanford Advisors


All Publications


  • Plasmonic Photocatalysis of Nitrous Oxide into N2 and O2 Using Aluminum-Iridium Antenna-Reactor Nanoparticles. ACS nano Swearer, D. F., Robatjazi, H., Martirez, J. M., Zhang, M., Zhou, L., Carter, E. A., Nordlander, P., Halas, N. J. 2019

    Abstract

    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-reactor plasmonic photocatalysts is reported. Under resonant illumination conditions, N2 and O2 are the only observable decomposition products, avoiding the problematic generation of NO x species observed using other approaches. Because no appreciable change to the apparent activation energy was observed under illumination, the primary reaction enhancement mechanism for Al-Ir is likely due to photothermal heating rather than plasmon-induced hot-carrier contributions. This light-based approach can induce autocatalysis for rapid N2O conversion, a process with highly promising potential for applications in N2O abatement technologies, satellite propulsion, or emergency life-support systems in space stations and submarines.

    View details for DOI 10.1021/acsnano.9b02924

    View details for PubMedID 31244036

  • Quantifying hot carrier and thermal contributions in plasmonic photocatalysis SCIENCE Zhou, L., Swearer, D. F., Zhang, C., Robatjazi, H., Zhao, H., Henderson, L., Dong, L., Christopher, P., Carter, E. A., Nordlander, P., Halas, N. J. 2018; 362 (6410): 69-+

    Abstract

    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-induced reduction of the thermal activation barrier for ammonia decomposition on a plasmonic photocatalyst. We introduce the concept of a light-dependent activation barrier to account for the effect of light illumination on electronic and thermal excitations in a single unified picture. This framework provides insight into the specific role of hot carriers in plasmon-mediated photochemistry, which is critically important for designing energy-efficient plasmonic photocatalysts.

    View details for DOI 10.1126/science.aat6967

    View details for Web of Science ID 000446547100043

    View details for PubMedID 30287657

  • Monitoring Chemical Reactions with Terahertz Rotational Spectroscopy ACS PHOTONICS Swearer, D. F., Gottheim, S., Simmons, J. G., Phillips, D. J., Kale, M. J., McClain, M. J., Christopher, P., Halas, N. J., Everitt, H. O. 2018; 5 (8): 3097–3106
  • Transition-Metal Decorated Aluminum Nanocrystals ACS NANO Swearer, D. F., Leary, R. K., Newell, R., Yazdi, S., Robatjazi, H., Zhang, Y., Renard, D., Nordlander, P., Midgley, P. A., Halas, N. J., Ringe, E. 2017; 11 (10): 10281–88

    Abstract

    Recently, aluminum has been established as an earth-abundant alternative to gold and silver for plasmonic applications. Particularly, aluminum nanocrystals have shown to be promising plasmonic photocatalysts, especially when coupled with catalytic metals or oxides into "antenna-reactor" heterostructures. Here, a simple polyol synthesis is presented as a flexible route to produce aluminum nanocrystals decorated with eight varieties of size-tunable transition-metal nanoparticle islands, many of which have precedence as heterogeneous catalysts. High-resolution and three-dimensional structural analysis using scanning transmission electron microscopy and electron tomography shows that abundant nanoparticle island decoration in the catalytically relevant few-nanometer size range can be achieved, with many islands spaced closely to their neighbors. When coupled with the Al nanocrystal plasmonic antenna, these small decorating islands will experience increased light absorption and strong hot-spot generation. This combination makes transition-metal decorated aluminum nanocrystals a promising material platform to develop plasmonic photocatalysis, surface-enhanced spectroscopies, and quantum plasmonics.

    View details for DOI 10.1021/acsnano.7604960

    View details for Web of Science ID 000413992800072

    View details for PubMedID 28945360

  • Heterometallic antenna-reactor complexes for photocatalysis PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Swearer, D. F., Zhao, H., Zhou, L., Zhang, C., Robatjazi, H., Martirez, J. P., Krauter, C. M., Yazdi, S., McClain, M. J., Ringe, E., Carter, E. A., Nordlander, P., Halas, N. J. 2016; 113 (32): 8916–20

    Abstract

    Metallic nanoparticles with strong optically resonant properties behave as nanoscale optical antennas, and have recently shown extraordinary promise as light-driven catalysts. Traditionally, however, heterogeneous catalysis has relied upon weakly light-absorbing metals such as Pd, Pt, Ru, or Rh to lower the activation energy for chemical reactions. Here we show that coupling a plasmonic nanoantenna directly to catalytic nanoparticles enables the light-induced generation of hot carriers within the catalyst nanoparticles, transforming the entire complex into an efficient light-controlled reactive catalyst. In Pd-decorated Al nanocrystals, photocatalytic hydrogen desorption closely follows the antenna-induced local absorption cross-section of the Pd islands, and a supralinear power dependence strongly suggests that hot-carrier-induced desorption occurs at the Pd island surface. When acetylene is present along with hydrogen, the selectivity for photocatalytic ethylene production relative to ethane is strongly enhanced, approaching 40:1. These observations indicate that antenna-reactor complexes may greatly expand possibilities for developing designer photocatalytic substrates.

    View details for DOI 10.1073/pnas.1609769113

    View details for Web of Science ID 000381293300038

    View details for PubMedID 27444015

    View details for PubMedCentralID PMC4987788

  • Metal-organic frameworks tailor the properties of aluminum nanocrystals SCIENCE ADVANCES Robatjazi, H., Weinberg, D., Swearer, D. F., Jacobson, C., Zhang, M., Tian, S., Zhou, L., Nordlander, P., Halas, N. J. 2019; 5 (2): eaav5340

    Abstract

    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, and photocatalytic properties. The MOF shell growth proceeds by means of dissolution-and-growth chemistry that uses the intrinsic surface oxide of the NC to obtain the Al3+ ions accommodated into the MOF nodes. Changes in the Al NC plasmon resonance provide an intrinsic optical probe of its dissolution and growth kinetics. This same chemistry enables a highly controlled oxidation of the Al NCs, providing a precise method for reducing NC size in a shape-preserving manner. The MOF shell encapsulation of the Al NCs results in increased efficiencies for plasmon-enhanced photocatalysis, which is observed for the hydrogen-deuterium exchange and reverse water-gas shift reactions.

    View details for DOI 10.1126/sciadv.aav5340

    View details for Web of Science ID 000460145700074

    View details for PubMedID 30783628

    View details for PubMedCentralID PMC6368424

  • Quantitative analysis of gas phase molecular constituents using frequency-modulated rotational spectroscopy. The Review of scientific instruments Lou, M., Swearer, D. F., Gottheim, S., Phillips, D. J., Simmons, J. G., Halas, N. J., Everitt, H. O. 2019; 90 (5): 053110

    Abstract

    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-dependent line shape and strength with partial pressure, and the multiple standing wave interferences and modulation-induced line shape asymmetries that sensitively depend on source-chamber-detector alignment. Here, we introduce a quantitative analysis methodology that overcomes these challenges, reproducibly and accurately recovering gas molecule concentrations using a calibration procedure with a reference gas and a conversion based on calculated line strengths. The technique uses frequency-modulated rotational spectroscopy and recovers the integrated line strength from a Voigt line shape that spans the Doppler- and pressure-broadened regimes. Gas concentrations were accurately quantified to within the experimental error over more than three orders of magnitude, as confirmed by the cross calibration between CO and N2O and by the accurate recovery of the natural abundances of four N2O isotopologues. With this methodology, concentrations of hundreds of molecular species may be quantitatively measured down to the femtomolar regime using only a single calibration curve and the readily available libraries of calculated integrated line strengths, demonstrating the power of this technique for the quantitative gas-phase detection, identification, and quantification.

    View details for DOI 10.1063/1.5093912

    View details for PubMedID 31153269

  • Environmental Symmetry Breaking Promotes Plasmon Mode Splitting in Gold Nanotriangles JOURNAL OF PHYSICAL CHEMISTRY C Smith, K. W., Yang, J., Hernandez, T., Swearer, D. F., Scarabelli, L., Zhang, H., Zhao, H., Moringo, N. A., Chang, W., Liz-Marzan, L. M., Ringe, E., Nordlander, P., Link, S. 2018; 122 (25): 13259–66
  • Exploring Scientific Ideas in Informal Settings: Activities for Individuals with Visual Impairments JOURNAL OF CHEMICAL EDUCATION Kumar, A., McCarthy, L. A., Rehn, S. M., Swearer, D. F., Newell, R. N., Gereta, S., Villarreal, E., Yazdi, S., Ringe, E. 2018; 95 (4): 593–97
  • Plasmon-induced selective carbon dioxide conversion on earth-abundant aluminum-cuprous oxide antenna-reactor nanoparticles NATURE COMMUNICATIONS Robatjazi, H., Zhao, H., Swearer, D. F., Hogan, N. J., Zhou, L., Alabastri, A., McClain, M. J., Nordlander, P., Halas, N. J. 2017; 8: 27

    Abstract

    The rational combination of plasmonic nanoantennas with active transition metal-based catalysts, known as 'antenna-reactor' nanostructures, holds promise to expand the scope of chemical reactions possible with plasmonic photocatalysis. Here, we report earth-abundant embedded aluminum in cuprous oxide antenna-reactor heterostructures that operate more effectively and selectively for the reverse water-gas shift reaction under milder illumination than in conventional thermal conditions. Through rigorous comparison of the spatial temperature profile, optical absorption, and integrated electric field enhancement of the catalyst, we have been able to distinguish between competing photothermal and hot-carrier driven mechanistic pathways. The antenna-reactor geometry efficiently harnesses the plasmon resonance of aluminum to supply energetic hot-carriers and increases optical absorption in cuprous oxide for selective carbon dioxide conversion to carbon monoxide with visible light. The transition from noble metals to aluminum based antenna-reactor heterostructures in plasmonic photocatalysis provides a sustainable route to high-value chemicals and reaffirms the practical potential of plasmon-mediated chemical transformations.Plasmon-enhanced photocatalysis holds promise for the control of chemical reactions. Here the authors report an Al@Cu2O heterostructure based on earth abundant materials to transform CO2 into CO at significantly milder conditions.

    View details for DOI 10.1038/s41467-017-00055-z

    View details for Web of Science ID 000403768500003

    View details for PubMedID 28638073

    View details for PubMedCentralID PMC5479834

  • Communicating Science Concepts to Individuals with Visual Impairments Using Short Learning Modules JOURNAL OF CHEMICAL EDUCATION Stender, A. S., Newell, R., Villarreal, E., Swearer, D. F., Bianco, E., Ringe, E. 2016; 93 (12): 2052–57
  • Al-Pd Nanodisk Heterodimers as Antenna-Reactor Photocatalysts NANO LETTERS Zhang, C., Zhao, H., Zhou, L., Schlather, A. E., Dong, L., McClain, M. J., Swearer, D. F., Nordlander, P., Halas, N. J. 2016; 16 (10): 6677–82

    Abstract

    Photocatalysis uses light energy to drive chemical reactions. Conventional industrial catalysts are made of transition metal nanoparticles that interact only weakly with light, while metals such as Au, Ag, and Al that support surface plasmons interact strongly with light but are poor catalysts. By combining plasmonic and catalytic metal nanoparticles, the plasmonic "antenna" can couple light into the catalytic "reactor". This interaction induces an optical polarization in the reactor nanoparticle, forcing a plasmonic response. When this "forced plasmon" decays it can generate hot carriers, converting the catalyst into a photocatalyst. Here we show that precisely oriented, strongly coupled Al-Pd nanodisk heterodimers fabricated using nanoscale lithography can function as directional antenna-reactor photocatalyst complexes. The light-induced hydrogen dissociation rate on these structures is strongly dependent upon the polarization angle of the incident light with respect to the orientation of the antenna-reactor pair. Their high degree of structural precision allows us to microscopically quantify the photocatalytic activity per heterostructure, providing precise photocatalytic quantum efficiencies. This is the first example of precisely designed heterometallic nanostructure complexes for plasmon-enabled photocatalysis and paves the way for high-efficiency plasmonic photocatalysts by modular design.

    View details for DOI 10.1021/acs.nanolett.6b03582

    View details for Web of Science ID 000385469800101

    View details for PubMedID 27676189

  • From tunable core-shell nanoparticles to plasmonic drawbridges: Active control of nanoparticle optical properties SCIENCE ADVANCES Byers, C. P., Zhang, H., Swearer, D. F., Yorulmaz, M., Hoener, B. S., Huang, D., Hoggard, A., Chang, W., Mulvaney, P., Ringe, E., Halas, N. J., Nordlander, P., Link, S., Landes, C. F. 2015; 1 (11): e1500988

    Abstract

    The optical properties of metallic nanoparticles are highly sensitive to interparticle distance, giving rise to dramatic but frequently irreversible color changes. By electrochemical modification of individual nanoparticles and nanoparticle pairs, we induced equally dramatic, yet reversible, changes in their optical properties. We achieved plasmon tuning by oxidation-reduction chemistry of Ag-AgCl shells on the surfaces of both individual and strongly coupled Au nanoparticle pairs, resulting in extreme but reversible changes in scattering line shape. We demonstrated reversible formation of the charge transfer plasmon mode by switching between capacitive and conductive electronic coupling mechanisms. Dynamic single-particle spectroelectrochemistry also gave an insight into the reaction kinetics and evolution of the charge transfer plasmon mode in an electrochemically tunable structure. Our study represents a highly useful approach to the precise tuning of the morphology of narrow interparticle gaps and will be of value for controlling and activating a range of properties such as extreme plasmon modulation, nanoscopic plasmon switching, and subnanometer tunable gap applications.

    View details for DOI 10.1126/sciadv.1500988

    View details for Web of Science ID 000216604200005

    View details for PubMedID 26665175

    View details for PubMedCentralID PMC4672758