Category Archives: Faculty Candidiate

Zintl and Polar Intermetallic Compounds

Chemistry Department Seminar Faculty Candidate
Dr. Fei Wang

Polymer and Material Chemistry, Lund University Sweden
Monday April 6, 2015
4:00 PM, MUB~ Alumni Lounge A

Zintl and polar intermetallic compounds are compounds between electropositive metals (e.g. alkali, alkaline earth, and rare earth) and electronegative metals/metalloids (e.g. late transition and post transition elements). Just like their constituent elements, these compounds are also metals/metalloids. Meanwhile, partial charge transfer is expected from the electropositive metals to the electronegative metals/metalloids, the latter of which are formal “anions” and covalent interactions can occur among them. Therefore, Zintl and polar intermetallic compounds possess simultaneously metallic, ionic, and covalent characteristics. I will demonstrate what will happen when metallicity, covalency, and ionicity coincide and interplay with each other.
Besides, the bonding between the “anionic” electronegative metals/metalloids is also intriguing. The well-know electron counting rules, such as the octet rule and the Wade-Mingo’s rules, fail frequently in rationalizing the bonding in Zintl and polar intermetallic compounds. I will present a few examples to illustrate the cause, with emphasis on the involvement of d-orbitals and the relativistic effects in bonding.

I obtained my master’s degree from Zhejiang University in China in 2005. There I worked on morphology controlled syntheses of inorganic compounds under the direction of Prof. Linhai Yue. After that, I joined Prof. Gordon J. Miller’s research group in Iowa State University, where I developed the majority of my expertise in solid state chemistry, including high temperature synthesis, X-ray crystallography, and first-principle computations. In 2011, I received my PhD degree in inorganic chemistry and moved to Stuttgart, Germany, working as a postdoc in Prof. Martin Jansen’s department in Max Planck Institute for Solid State Research. My project is on the syntheses, structures, and rationalization of thallium cluster compounds featuring significant relativistic spin-orbit coupling. Currently, I am in Prof. Sven Lidin’s group at Lund University in Sweden, working on my second postdoc position which started in 2013 and is supported by the Wenner-Gren Scholarship. Here, my expertise has been further broadened with incommensurate crystallography and thermoelectric materials.

Sustainable Clean Energy Based on Solid State Ionic Materials and Devices

Chemistry Department Seminar Faculty Candidate
Dr. Jianhua Tong
Colorado Center for Advanced Ceramics,
Metallurgical & Materials Engineering, Colorado School of Mines
Thursday March 19, 2015
MUB ~ Alumni Lounge A
1:00 pm

It is estimated that global energy consumption will be doubled by 2035 due to growth in global population and continued industrialization of developing countries. Solar energy is a renewable clean energy source and can satisfy the rising energy demand eventually from long-term point of view. However, fossil energy, a non-renewable carbon-based energy source, still dominates the energy supplies in near future. Therefore, the efficient conversions of fossil energy and the efficient storage of solar energy are also very important from both scientific and industrial point of view. Among the energy materials, the leading actors for energy conversion and storage, solid state ionic materials have found a great number of applications such as catalytic membrane reactors, fuel cells, electrolysis cells, heterogeneous catalysts, photovoltaics, thermal electronic devices, materials for solar thermal chemical fuels production, and catalysts for oxygen reduction reaction and oxygen evolution reaction etc.
In the first part of the talk, I would like to briefly highlight my significant research contributions to sustainable clean energy based on solid state ionic materials and devices. In the second part of the talk, I would like to intensively focus on my recent discovery of perovskite-type oxides as promising materials for solar thermochemical (STC) fuels production through two-step redox cycles.

Dr. Jianhua Tong is working as an Associate Research Professor in Colorado Center for Advanced Ceramics at the Colorado School of Mines (US). He received his PhD degree in Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Subsequently, he worked as NEDO project researcher in Research Institute of Innovative Technology for the Earth (Japan), JSPS fellow in National Institute of Advanced Industrial Science and Technology (Japan), and postdoctoral scholar in California Institute of Technology (US) for several years. He has made some important contributions to the materials and devices for sustainable clean energy by focusing on fuel cells, catalytic membrane reactors, pure hydrogen production, pure oxygen production, natural gas conversion, mixed conducting oxides, proton conducting ceramics, and solar thermochemical fuels etc. He published >60 peer-reviewed papers, filed >15 patents, and got citations >2500 and H-index >24.

Exploring environmentally relevant aqueous interfaces and reactions on solid surfaces

Chemistry Department Seminar Faculty Candidate
Dr. Kathryn A. Perrine

Department of Chemistry, University of California Irvine
Monday March 16, 2015
Chem-Sci 101
4:00 pm


Ions and solutes impact chemistry at the aqueous liquid/vapor interface, particularly in environmental chemistry where aerosols can carry pollutants into the atmosphere and react to form harmful byproducts. Liquid Jet X-ray Photoelectron Spectroscopy technique probes the surface and bulk of aqueous solutions. Low photoelectron kinetic energies are used to probe the surface layers of solutions and higher photoelectron kinetic energies probe deeper into the bulk of aqueous solutions. Binary acetonitrile-water mixtures are shown to be inhomogeneous and that the surface forms a saturated dipole layer near 0.2 mole fraction. These studies are contrasted to ternary solutions that have added ions from salts that affect the interface of organic solutes. Potassium iodide was added to aqueous acetonitrile and propionitrile solutions to observe the effects of ions on the surface nitrile distributions. Results from other salt solutions suggest specific cation effects are unexpected and apparent at the aqueous interface. These studies help elucidate the role ions play at the interface of aqueous organic solutions.

Solid interfaces can also have an impact on reactions in catalysis and in the environment. Supported metal oxide structures that are commonly found in urban and rural environments can produce various byproducts with pollutants through core-hole activation in the presence of UV and visible light. In order to understand how the interface is impacted on heterogeneous surfaces, thermal desorption studies of water on different heterogeneous structured TiO2 materials were investigated. Results suggest as the size of the metal oxide decreases, its physical properties change its chemistry and reactivity. Monolayer and second layer activation energies of water were determined on different graphite supported TiO2 structures, ranging from supported nanoparticles to thin films. These studies compare the reactivity of small molecules, representative of those in the air/water environment, and will help explain gas/solid reactions on heterogeneous supported metal oxide materials for catalysis and environmental applications.

Dr. Kathryn A. Perrine found a passion for surface science as an undergraduate student at the University of South Carolina, where she worked on characterizing the decomposition of metal encapsulated dendrimers for supported metal catalysis applications. She then attended graduate school and earned her PhD at the University of Delaware, where she studied semiconductor surface science. Her work there focused on understanding how Cu nanostructures grow on different functionalized silicon surfaces from chemical vapor deposition of copper metal-organic precursors. She also collaborated with researchers at the Materials Science Department to examine how organic molecules react on silicon for future use in organic electronics. There she won the competitive University of Delaware Professional Development Award for her research accomplishments. She also completed a full year in teaching in higher education by completing the Higher Education Teaching Certification.

She later went on to do postdoctoral work at the University of California, Irvine mainly focused on Liquid-Jet X-ray Photoelectron Spectroscopy (LJ-XPS). She collaborated with researchers at the BESSY II light source at the Helmholtz Center for Materials and Energy on aqueous and acidic systems. She helped build a separate LJ-XPS system at Beam line 11.0.2 end station at the Advanced Light Source at Lawrence Berkeley National Laboratory to continue aqueous liquid jet studies in a higher pressure environment. She collaborated with others in the Hemminger group to investigate other projects, including hydrocarbon decomposition on supported Pt nanoparticles and understanding the reactivity of supported TiO2 materials for heterogeneous catalysis applications. There she was a member of the Postdoctoral association and received the UCI postdoctoral service award for developing a seminar series for postdoctoral teaching. She currently works as a visiting postdoctoral scholar at the Joint Center for Photosynthesis at the California Institute of Technology on heterogeneous catalysts for electrochemical solar energy conversion.

Impact of Molecules, Morphology and Nano/microstructures in Sensing, Optical, Energy and Display applications

Chemistry Department Seminar Faculty Candidate
Dr. Kaushik Balakrishnan

Monday March 2, 2015 – 4:00 PM
Chem-Sci 101

The ability to control optical and electrical properties of materials as a function of size and dimension has profound implications in numerous miniaturized technologies such as sensing, communication, lighting, display, optical and electrical circuits, and energy applications. This talk will unravel critical information about molecular stacks from individual molecular entities and advance to our newly uncovered possibilities to co-¬‐localize, and co-¬‐assemble two distinct molecular entities in a single stack of highly organized assemblies. Such self-¬‐assembled structures show immense potential in photonic and opto-¬‐electronic devices and are a promising approach for advancing organic electronic materials in advance applications.
Second part of this talk will focus on energy harvesting and storage. The nanocarbon structures such as carbon nanotubes, and graphene are highly attractive for use as electrodes in supercapacitors, and lithium ion batteries. The detailed workings of the recent breakthroughs in ‘in-¬‐plane’ geometry that enables an ultrathin, flexible, and solid-¬‐state graphene based supercapacitors will be described. Also, nanocomposites for achieving high performance electrolytes capable of withstanding high temperatures with large voltage windows for next generation of supercapacitors and batteries will also be described.