Controlled Synthesis, Processing and Applications of Structural and Functional Nanomaterials: Two Dimensional Nanomaterials
Sponsored by: MS&T Organization
Program Organizers: Kathy Lu, Virginia Tech; Xudong Wang, University of Wisconsin - Madison; Eugene Olevsky, San Diego State University; Gurpreet Singh, Kansas State University; Nitin Chopra, The University of Alabama; Pu-Xian Gao, University of Connecticut; Jianyu Liang, Worcester Polytechnic Institute

Wednesday 8:00 AM
October 19, 2011
Room: C123
Location: Greater Columbus Convention Center

Session Chair: Pu-xian Gao, University of Connecticut

8:00 AM  Invited
Optical Thin Films for Gas Sensing in Advanced Coal Fired Power Plants: Paul Ohodnicki1; Thomas Brown1; Congjun Wang1; Christopher Matranga1; 1National Energy Technology Laboratory
    The National Energy Technology Laboratory (NETL) is developing technologies for the next generation of higher-efficiency, lower emission fossil-fueled power plants, including oxy-fuel combustion processes for carbon capture and sequestration, and coal gasification to produce H2-rich synthetic gas which can be converted to electrical power using solid-oxide fuel cells or gas turbines. Improved sensor technologies that can operate under extreme conditions (high temperature, high pressure, corrosive gases) are needed for process monitoring and control. Optical sensors based on metal oxide thin films are important candidates, and an improved understanding of the fundamental link between structural/chemical changes in thin films and measured optical properties in the presence of various gas species under relevant conditions is needed to aid in sensor development efforts. Results of synthesis and characterization of metal oxide-based films will be presented, and future work plans that fully leverage unique expertise and facilities available at NETL will be discussed.

8:40 AM  
Large-Scale Synthesis of MoS2/ Polymer Derived Ceramic Composite Nanosheets: Lamuel David1; Romil Bhandavat1; Uriel Barrera1; Gurpreet Singh1; 1Kansas State University
    Bulk MoS2 crystal is composed of vertically stacked and weakly interacting layers held together by van der Waals forces. Recently, MoS2 nanosheets have been a topic of great interest; tribological and semiconducting properties are particularly of interest. Applications of MoS2 as lithium ion battery anode material are also being explored. Here, we demonstrate exfoliation of MoS2 into single and few layers. The exfoliated nanosheets are then functionalized with polymer-derived Si/C/N (ultra-high temperature oxidation resistant ceramic) through controlled thermolysis of a liquid polymer. Chemical structure, electrochemical and optical behavior of the functionalized nanosheets is studied by use of various spectroscopic techniques. The composite nanosheets may find applications as a low coefficient of friction/high temperature (~1300 C) lubricant and a durable negative electrode material for rechargeable batteries.

9:00 AM  
Silicon Nitride Nanowire Papers Synthesized by Silica Nanopowders and Silica Gel: Kei-Peng Jen1; Sridhar Santhanam1; Jih Guo1; 1Villanova University
    Silicon nitride nanowire papers are extremely desirable for reinforcing different types of composites for structure applications and/or for providing excellent thermal insulation for high temperature applications. In this study, silicon nitride nanowire papers were synthesized by heating mixtures of silica nanopowders (5-15nm)/ silica gel (~300 mesh size) with activated charcoal at 1450C for 6hrs in the presence of high purity nitrogen. The powder mixtures were molded in pellets interlaced with graphite wafers and placed in cylindrical graphite crucible. The crucible was then placed vertically in the horizontal alumina tube furnace, with a flow of nitrogen. A unique process was successfully developed using the horizontal alumina furnace to harvest silicon nitride nanowire papers directly from the graphite wafers. The paper was then characterized by using the SEM, XRD, and ATF-FTIR. Thermal conductivity, bulk density, and the strength of silicon nitride nanowire papers were also measured to characterize physical and mechanical properties.

9:20 AM  
Synthesis of Nano-Structured Metal-Oxides and Deposition via Ink-Jet Printing on Microhotplate Substrates for Applications in Gas Sensing : Mark Andio1; Patricia Morris1; 1Ohio State University
    Recently, nano-structured metal-oxides have shown improved sensitivity compared to micron or nano size particles to trace levels of gases due to enhanced surface-to-volume ratio. They have also shown shorter response and recovery times to hazardous gases which are beneficial for fast monitoring and quick detection of gases. The objective of this study was to synthesize numerous metal oxide nano-structures including TiO2, Nb-doped TiO2, and SnO2 and deposit these materials on microhotplate sensor substrates to study the effect of the resulting metal-oxide film microstructure on gas sensing properties. The materials were deposited using an ink-jet printer (IJP), and suspension formulations for compatibility with this deposition system will be thoroughly discussed. Evaporation and drying properties of the particle-laden suspensions after deposition on microhotplate substrates will also be developed. Finally, gas sensor results of the nano-structured metal-oxides on microhotplate sensor substrates will be presented.

9:40 AM Break

10:00 AM  Invited
Toward More Efficient Photocathode for Dye-Sensitized Solar Cells: Yiying Wu1; 1Ohio State University
    Within two decades of the advent of the dye-sensitized solar cell (DSC), the efficiency of the TiO2 photoanode-based DSC has been gradually increased to 11%. In order to achieve further substantial increase in the efficiencies, radical approaches might be required. Construction of tandem DSCs, consisting of a dye-sensitized TiO2 photoanode and a dye-sensitized photocathode of a suitable p-type semiconductor, is an attractive approach in terms of extending the open-circuit voltage of the cell. With a judicious choice of the two dyes that sensitize anode and cathode respectively, their combination in a tandem DSC can cover a broader solar spectrum than a single-absorber DSC. In this presentation, I will discuss our progress in pursuing more efficient p-DSCs through new semiconductors and sensitizers.

10:40 AM  Invited
Application of ZnO Nanowires for Energy Harvesting Technology: Rusen Yang1; 1University of Minnesota
    Being the richest family with nanowires (NWs)/nanobelts, nanosprings, nanorings, nanohelixes, and nanotubes, ZnO nanostructures are unique not only for the fabrication of nanosensors, but also for its ability to harvest mechanical energy enabled with the piezoelectric property. The energy harvesting unit with nanomaterials is critical to achieve independent and sustainable operations of nanodevices. Innovative nanotechnologies with ZnO nanowires will be discussed for converting mechanical energy (such as body movement, muscle stretching) and vibration energy (such as acoustic/ultrasonic wave) into electric energy. The generated electricity from ZnO nanowires can power directly a nanowire pH sensor or a nanowire UV sensor. The electric energy from ZnO nanowire can also be stored to power light emitting diode. This nanotechnology demonstrated with ZnO nanowires implies feasible approach for a power unit of a self-powered nanosystem, and it also indicates a novel approach for powering small size personal electronics.

11:20 AM  Student
TiO2 Photocatalyst Thin-Film Coatings on Polyethylene Terephthalate: Huynh Pham1; Julian Cox1; Chris Sorrell1; 1The University of New South Wales
    Photocatalytic thin films of TiO2 were deposited onto PET substrates at atmospheric pressure using low-temperature and low-cost processes. The route involved the preparation of stable aqueous sols of TiO2 at ~95C, film deposition by dip-coating, and post-deposition drying at ~130C. The resultant coatings were characterised by HRSEM, HRTEM, FIB, XRD, XPS, AFM, laser Raman microspectroscopy, and UV-VIS spectrophotometry. The films were observed by HRSEM and AFM to be comprised of nanocrystallites of 5-10 nm diameter and nanoagglomerates of 15-25 nm size. The films were determined by XRD and laser Raman microspectroscopy to consist of anatase, with a trace of brookite. Under UV irradiation, all films exhibited photocatalytic activity, as measured by the photo-oxidation of methylene blue.

11:40 AM  Student
Magnetic Response and Nano-Structural Variations of Ni, Co, and Fe-Doped Y2O3-Stabilized ZrO2: Amy Morrissey1; Josh White1; Jianhua Tong1; Jim O'Brien2; Ivar Reimanis1; 1Colorado School of Mines; 2Quantum Design, Inc.
    Y2O3-stabilized ZrO2 (YSZ) is a critical material in electrochemical devices. Doping with metals M (M = Ni, Co, Fe etc.) in YSZ can form intriguing nanostructures with engineered electrical conductivities for enhancing electrochemical performance. In this work, the effect of these dopants is examined by high sensitivity SQUID based magnetometry. YSZ-M nanocomposite powders with varying amounts of dopant are synthesized using a sol-gel method. Thermal processing parameters are introduced to investigate nano- and microstructure of YSZ-M powders. A suite of characterization techniques are employed to quantify nano-structural features and compare with magnetic signatures. The results show that magnetometry is a useful in describing the nanostructure of the metal-doped oxides.