Green Energy Technology Projects - 2014
Adapted from X. Chen, L. Liu, P.Y. Yu, S.S. Mao, Science 331(2011) 746.
Visible Light Photocatalysis for Biofuels Synthesis
Faculty Mentor: Fuat E. Celik
Graduate Student Mentor(s): Deniz Dindi, Ashley Pennington
Project Description: As an inexhaustible source of energy, harnessing solar radiation is an appealing goal in renewable energy production. In addition to well-known photovoltaic and solar thermal routes, photons can also promote catalytic reactions in semiconductor materials. Amongst semiconductors, TiO2 is very stable under photocatalysis conditions. Several photocatalytic reactions have been reported on TiO2 and TiO2-supported transition metals. However, with a large band gap (3.2 eV), TiO2 only absorbs ultraviolet light. This project will investigate methods for creating photocatalysts based on TiO2 that are active under visible light irradiation.
Chemical Catalysis for Solar Fuels
Faculty Mentor: G. Charles Dismukes
Graduate Student Mentor(s): Graeme Gardner, Anders Laursen, Bin Liu, Paul F. Smith
Project Description: Producing renewable fuels, such as hydrogen (H2) by water-splitting, from fossil-free electricity is a grand challenge for developing sustainable energy systems. H2 is also a major bulk chemical produced at ~63Mton/yr from natural gas. Consequently, research has focused on developing alternative, cheaper, and robust catalysts made from earth-abundant elements.
Catalysis opportunities in the Dismukes group include H2 and O2 evolution from water via metal phosphides and oxides, respectively (shown in Figures 1 and 2).
The Dismukes group is also seeking to develop catalysis projects to produce chlorine dioxide for water purification, and reduce CO2 to carbon fuels via biomimetic processes (Depicted in Figures 3 and 4)
Figure 1: Atomic structure of metal phosphides currently under investigation.
Figure 2: Evolution of H2 and O2 from water via oxides.
Figure 3: Reduction of Co2 to carbon fuels via biomimetic processes.
Figure 4: Catalysis project focused on production of chlorine dioxide for water purification.
Energy Harvesting with Inflatable Structures
Faculty Mentor: Aaron Mazzeo
Graduate Student Mentors: Jingjin Xie and Ke Yang
Project Description: We have been simulating and characterizing lift and drag on airfoils with silicone-based inflatable structures. By inflating the elastomeric regions of airfoils, we can alter their surface area and manipulate flow surrounding the entire structure.
The Mazzeo group is expanding the project to study vortex shedding on cylinders or other morphable geometries with fluid flows to create alternative forms of energy harvesting. The anticipated methods of transduction from mechanical excitation to electrical output include piezoelectric materials and linear electromagnetic generators. A participant would get to work with graduate and undergraduate students on designing, constructing, and testing systems with embedded, inflatable structures. The construction of the inflatable structures generally involves the use of three-dimensionally printed molds to form silicone-based elastomeric bladders. We will combine these structures with harder supporting materials and integrate them with an electromechanical system. After building prototypes and coupling the structures with an electrical generator, we will run experiments in wind tunnels located on campus to characterize their performance/efficiency and the amount of power we can produce.
Ammonia tolerance in bacteria during anaerobic processing of wastes to produce bioenergy
Faculty Mentor: Donna E. Fennell
Graduate Student Mentor(s): Amanda Luther and Sunirat Rattana
Project Description: Anaerobic processing of wastes such as source separated human wastes, sewage, municipal solid waste and animal wastes releases abundant ammonia. Ammonia at high concentrations can inhibit the fermentative microbial communities that produce it. Ammonia is a highly regulated water pollutant that is useful when harvested as a fertilizer. Additionally, there is emerging interest in ammonia as an energy source for producing hydrogen or electricity. In this project, researchers are determining how ammonia can be produced more efficiently from waste biomass, how microbes that are exposed to ammonia resist its toxicity, and how ammonia can be used as a biofuel.
Project : Few-layer graphene synthesis using pulsed laser deposition
Faculty : Stephen Tse
Graduate Student Mentors : William Mozet
Project Description: Graphene research has surged in recent years due to its incredible properties, such as ballistic electron transport and high tensile strength to weight ratio, suggesting staggering potential applications. Efforts to produce graphene have naturally followed. Using an Nd:YAG laser of 266 nm to ablate highly ordered pyrolytic graphite (HOPG), graphene is fabricated on polished copper substrates for varying times (T= 900ºC, P=10-5 Torr, E=50 mJ/pulse). The graphene is examined using Raman spectroscopy with a focus on studying the number of layers grown as a function of the time of deposition using peak intensity ratios. It has been determined that the number of graphene layers decreases with decreasing deposition time while the disorderedness of the graphene crystals remain unaffected. This study advances the current state of knowledge on graphene synthesis, aiding in further efforts to not only create graphene, but also study its properties and seemingly countless potential applications.
Representative scanning electron microscope images of nanoporous silver films with different porosities prepared by a thermally-assisted substrate de-wetting method.
Project: Nanoporous Metals for Polymer Optoelectronics: Large-Area Fabrication and Optical Characterization
Faculty: Deirdre O’Carroll
Graduate Student Mentor: Zeqing Shen
Project Description:To enable next-generation, nanostructured organic polymer semiconductor-based optoelectronic devices, high-throughput, large-area, low-cost methods to pattern metal electrode surfaces are necessary. Additionally, conjugated polymer chain orientation has shown great influence on charge-carrier mobility and overall performance of large-area organic optoelectronic devices . Although, numerous prior studies have characterized polymer chain alignment in bulk or thin-film environments, the chain organization behavior of semiconducting conjugated polymers in nanostructured or confined environments is expected to be very different from that in planar or bulk formats and could lead to improved optical or electrical properties . In this project, we develop fabrication and characterization techniques for large-area nanoporous metals (NPMs) and investigate their use as a platform to control or modify conjugated polymer chain alignment for optoelectronic applications. We wish to investigate how the structure of the patterned metal electrode and the resulting changes in polymer chain organization can improve the light-emitting properties of the polymer relative to those on planar metal electrode surfaces.
References: M. Aryal, K. Trivedi, W. Hu, ACS Nano. p3085 (2009), K. Shin, S. Obukhov, J. T. Chen, J. Huh, Y. Hwang, S. Mok, P. Dobriyal, P. Thiyagarajin, T. P. Russell, Nature Mater. 6, p961 (2007). K. R. Williams, K. Gupta, M. Wasilik, J. Microelectromech. Sys. 12 (2003). L. Qian, X. Yan, T. Fujita, A. Inoue, M. Chen, Appl. Phys. Lett. 90, p153120 (2007).
Project: Developing glasses for their application in ZEBRA batteries
Faculty: Ashu Goel
Project Description: ZEBRA battery (Technical name: Na-NiCl2 battery) was invented in 1985 by the Zeolite Battery Research Africa Project (ZEBRA) group led by Dr. Johan Coetzer in South Africa. ZEBRA battery operates at ~250 oC and utilizes molten sodium aluminumchloride (NaAlCl4) as the electrolyte, molten sodium as negative electrode and nickel in discharged state and nickel chloride (NiCl2) in charged state as positive electrode. Since both NaAlCl4 and Na are liquid at the operating temperature, a sodium-conducting beta-alumina (Al2O3) ceramic is used to separate the liquid sodium from molten NaAlCl4 while alpha-Al2O3 is used as an insulating collar and a suitable glass based material is applied to join the two ceramic components. The purpose of the glass seal is to maintain a hermetic and robust sealing between alpha- and beta-Al2O3 ceramic components in the battery while being exposed to hostile alkali- and halide vapor rich environment at operating temperatures. The primary requirements for designing a suitable glass sealant for ZEBRA batteries are as follows: minimum thermal expansion mismatch between glass and ceramic components; high thermal shock resistance; high chemical resistance towards alkali vapors and low electrical conductivity.
PZT-Carbon multiwalled epoxy thick film with graphene monolayer. 
Project: Percolative Dielectric Materials for Energy Storage Applications
Faculty: Kimberly Cook-Chennault
Graduate Student Mentors: Udhay Sundar and Wanlin Du
Project Description: Electrical energy storage plays a key role in electronics, stationary power systems, hybrid electric vehicles and pulse power applications. Traditionally, bulk ceramic dielectric oxides have been used for these applications, though they suffer from inherently low breakdown field strength, which limits the available energy per unit mass (energy density) and increases the dielectric loss. On the other hand, polymers have high break down field strengths, low dielectric losses and can be readily processed into thin films, but suffer from relatively low dielectric permittivity, and thus low energy densities. This project focuses on development of materials that can be applied to sub-micrometer scale commercial and industrial devices such as, high density DRAM (dynamic access memory), non-volatile memory (NRAM) and capacitors. It is well known that coupling polymer and a dielectric constant material into a composite may address some of the aforementioned challenges, though the mechanisms that lead to higher dielectric constants and minimal dielectric losses are not well understood. Hence students will fabricate and analyze composite dielectric materials with the aim of understanding the mechanisms that lead to higher dielectric constants and higher breakdown field strengths.
 Multi-Walled Carbon-Nanotube Based Flexible Piezoelectric Films with Graphene MonolayersS Banerjee, R Kappera, KA Cook-Chennault, M ChhowallaEnergy and Environment Focus 2 (3), 195-202
Project: Bulk thermoelectric characterization setup
Faculty: Mona Zebarjadi
Graduate Student Mentor(s): Wenqing Shen, Vijay Vembuli, Xiaobing Zhang
Project Description: Thermoelectric power generators are used to directly convert thermal energy into electricity and they can be used in waste heat recovery and solar thermal energy conversion. The efficiency of the thermoelectric devices, highly depend on the quality of the materials used. Three coefficients, electrical conductivity, thermal conductivity and Seebeck coefficient are determining the materials efficiency. In this project we will assemble a setup to characterize these three parameters. This setup is made after a unique setup developed in Armey Research Laboratory, enabling us to measure the three parameters at the same time.
Figure 1: Solar array of Gratzel cells that were constructed using Titanium Dioxide.
Figure 2: Scanned electron micrograph of nanosized titania powder.
Project: Prepare Dye-sensitized Grätzel Solar Cells with Titanium Dioxide (TiO2)
Faculty: Lisa Klein
Project Description: Solar technology is gaining wide popularity because it is an alternative source of energy. Photovoltaic panels are used to harness the energy from the solar radiation.Teachers will learn how to prepare dye sensitized Gratzel solar cells that incorporate Titanium Dioxide (TiO2).
In Figure 1, a solar array comprised of Gratzel cells is presented. These cells are made from a layer of TiO2 nanoparticles. TiO2 is a semiconductor and ubiquitous in commercial products. It provides whiteness and opacity to products such as paints, coatings, plastics, papers, inks, foods, and most toothpaste. TiO2 is also used in sunscreens to block harmful UV B radiation from the sun. In this project, a paste of nanometer TiO2 particles and viscous organic compounds is spread onto transparent conductive glass (F-doped SnO2). A dye is used to absorb the photons. A scanned electron micrograph of nanosized titania powder is as shown in Figure 2. In Figure 3, an assembled device with electrical contacts.
Students will experience hands-on sample preparation and characterization, statistical analysis of processing variables.
Figure 3: Assembled device with electrical contacts