Yugang Sun, Argonne National Laboratory
Andrea Tao, University of California, San Diego
Congjun Wang, National Energy Technology Laboratory
Hua Zhang, Nanyang Technological University
Symposium Support Nanoscience|Royal Society of Chemistry
O2: Plasmon Enhanced Photocatalysis I
Monday PM, November 30, 2015
Sheraton, 2nd Floor, Back Bay B
2:30 AM - *O2.01
Plasmons, Hot Electrons and Photocatalysis
Martin Moskovits 1 Will Elliott 1 Syed Mubeen 2
1Univ of California-S Barbara Santa Barbara United States2University of Iowa Iowa City United StatesShow Abstract
Surface plasmons live for a few femtoseconds. On dephasing, they produce a shower of energetic electrons and holes that equilibrate adiabatically over 10-100 femtoseconds to form a Fermi distribution with electron temperatures of several thousands of Kelvin. Most of the energy of this hot electron gas is then dissipated through electron-phonon interactions over a few picoseconds. By fabricating appropriately nanostructured devices allowing a reasonable fraction of these hot carriers to be harvested before they thermalize, the hot electrons can be transferred to appropriate catalyst systems and the device can be used to carry out light-enabled redox chemistry. To do this efficiently one needs to design and construct materials and systems with appropriate dielectric properties, structures and architectures, and interfaces of the appropriate relative band properties to irreversibly extract the carriers in the handful of picoseconds during which they are “hot”, and to design a new suite of catalytic materials that collaborate appropriately with the plasmonic system and the electrons (and holes) that are produced by them. Although the problem seems formidable, remarkable progress has recently been achieved by several groups internationally. Our focus has been on using plasmonic materials as absorbers and photocatalysts for artificial photosynthesis, some examples of which will be presented and discussed.
3:00 AM - O2.02
Plasmon-Enabled Photothermal Hydrogen Generation in Cold Reactor
Nico Hotz 1 Titilayo Shodiya 1
1Duke University Durham United StatesShow Abstract
High activation barriers of rate-limiting reaction steps require many conventional heterogeneous catalytic reactions to be operated at relatively high temperatures. This study suggests that the combination of nanoscale catalysts and plasmonic nanostructures can locally overcome the activation barrier under sunlight without requiring high temperatures in the bulk of the reactor material.
To date, the execution of electron-driven photocatalysis has been demonstrated on coinage (Ag, Au, and Cu) metal nanoparticles through the excitation of Localized Surface Plasmon Resonance (LSPR), where LSPR excitation is used to transfer photon energy to nearby semiconductors, molecular photocatalysts, and metals.
This study demonstrates the first proof of hydrogen generation via alcohol steam reforming at a local temperature above 200°C, achieved by plasmonic heating under moderately concentrated solar irradiation, in an otherwise cold photocatalytic reactor. The plasmonic heating is localized in time and space, allowing the use of a high-temperature catalytic process without excessive heating of the immediate surroundings.
3:15 AM - O2.03
Engineering Localized Surface Plasmonic Interactions in Gold by a Silicon Nano-Antenna for Enhanced Heating and Photocatalysis
Daksh Agarwal 1 Carlos Aspetti 1 Matteo Cargnello 1 2 Christopher B. Murray 1 Ritesh Agarwal 1
1University of Pennsylvania Philadelphia United States2Stanford University Stanford United StatesShow Abstract
The field of plasmonics has attracted a lot of attention in recent years because of potential applications in various fields such as photovoltaics, energy production and conversion, catalysis and therapeutics. We report, for the first time, highly engineered ‘Omega;&’ (omega) shaped nanowire-dielectric-metal (Si-SiO2-Au) structures in which cavity effects of core antenna have been used to enhance the localized surface plasmons in metallic films. These plasmonic interactions can be easily controlled by tuning the antenna properties. The degree of enhancement has been measured by cavity heating and temperatures close to 1000K have been successfully measured for an antenna size resonant with excitation wavelength. Photoreforming reactions performed on these cavities showed ~50% enhancement in hydrogen production compared to control samples. Because of the ease of synthesis, nature of enhancement and high temperature stability of these structures, we expect them to have applications in the field of energy conversion and high temperature catalysis. This work also demonstrates successfully, temperature measuring capability of a plasmonic system and presents a technique to study high temperature properties of various materials.
3:30 AM - *O2.04
Visible-Light, Plasmonic, Heating for Catalytic CO2 Conversion Applications
Christopher Matranga 1
1NETL Pittsburgh United StatesShow Abstract
Managing carbon emissions is one of the most pressing issues currently faced by the energy sector. One interesting approach for dealing with these emissions is to catalytically convert CO2 into liquid fuels, olefins, aromatics, and industrial chemicals that can be sold to offset carbon management costs. This approach requires the development of novel catalysts capable of utilizing carbon-friendly forms of energy to activate CO2 and drive a chemical reaction. My talk will focus on a very simple Au-ZnO heterostructure where visible-light plasmonic excitation of the Au generates heat to drive chemical reactions on the ZnO substrate. In this system, CO2 and H2 can be converted to CH4, CO, and H2O through a chemical pathway that experiments and thermodynamic simulations show is entirely thermal. The instantaneous and localized nature of plasmonic heating offers many advantages and challenges for reactor design and heat management in catalytic processes. These aspects of plasmon-based reaction engineering will also be highlighted.
O3: Synthesis and Fabrication of Functional Plasmonic Nanostructures I
Monday PM, November 30, 2015
Sheraton, 2nd Floor, Back Bay B
4:30 AM - *O3.01
Cooperative Functions in Engineered Light-Harvesting Systems: From Supramolecules to Metamaterials
Yuebing Zheng 1
1Univ of Texas-Austin Austin United StatesShow Abstract
In human body, nature has vividly demonstrated that biological molecular motors in precise assemblies function cooperatively to link the chemical-mechanical energy conversion from molecular-scale to macroscopic world for useful work. Inspired by nature, we design, measure and control cooperative functions in engineered systems in order to better harness light for improved applications. Herein, we report our advances in two types of cooperative light-harvesting systems based on light-driven supramolecules and plasmonic metamaterials. Advanced nanotools are applied to improve the fundamental understanding and control of the nanoscale light-matter interactions in these systems down to the single-molecule and single-nanoparticle levels. We leverage our improved understanding to develop the rational design of the systems where molecules and nanoparticles as building blocks assemble precisely and function cooperatively to control light concentration and enhancement or to convert light into other forms of energy for useful work. Once fully developed, cooperative functions in the engineered systems will pave the way towards enhanced light harvesting for energy and healthcare applications.
5:00 AM - O3.03
Size-Dependent Surface Enhanced Raman Scattering Activity of Plasmonic Nanorattles
Keng-Ku Liu 1 2 Sirimuvva Tadepalli 1 2 Limei Tian 1 Srikanth Singamaneni 1 2
1Washington University in St. Louis St. Louis United States2Washington University in St. Louis St. Louis United StatesShow Abstract
Surface enhanced Raman scattering (SERS) involves the dramatic enh