Assistant Professor of Chemistry
Ph.D.| University of California, Los Angeles, 2007
Postdoctoral Fellow | California Institute of Technology, 2007-2010
In recent history our society has relied on non-renewable sources (such as coal, oil, and uranium) to satisfy our energy needs; we could continue doing so for thousands of years before running out of fossil fuels (coal, especially, is abundant). However, it is likely that our consumption of fossil fuels is having a significant impact on our habitat, the earth, through anthropogenic global warming. Carbon dioxide, which is produced when burning fossil fuels, is a green-house gas. Carbon-neutral energy sources allow us to enjoy modern comforts while affecting our environment less. The sun supplies far more energy to the earth than we are currently consuming, yet we are still relying on fossil fuels to meet most of our energy needs. Solar-energy will likely not be our main source of energy until it is economically competitive with fossil fuels. Less expensive, and thus more competitive, solar-to-usable energy conversion devices can be realized by improving efficiency, and reducing the cost of the materials used to make photovoltaic (PV), and PEC (photoelectrochemical) devices. My research interests are all aimed at addressing these issues. The research provides great opportunities for working on solving present problems, while doing fundamental science. Researchers will have the opportunity to explore electronic, electrochemical and chemical properties of materials and surfaces.
Research Areas of Interest:
Surface Chemistry of III-V semiconductors. We are developing new surface chemistry of III-V semiconductors. Efficiency and stability of semiconductor devices is highly dependent on surface-properties. We are exploring the relationship between surface identity and chemical and electrical properties.
Electron Transfer in DSSCs. Dye Sensitized Solarcells (DSSCs), are low-cost, and easy to make. However, they are currently less efficient than many inorganic semiconductor PV devices. Electron-transfer processes ultimately determine the efficiency of DSSCs. We are investigating the effects of chemical identity on electron-transfer processes. Figures of merit are used as feed-back variables to help direct future research.
Visible Light Absorbing Photoanodes. To store solar-energy as Hydrogen through water-splitting one must not only reduce water (or H+) to H2 but also oxidize water (or OH-) to oxygen since the full water-splitting reaction can be written as: 2H2O –> 2H2 + O2. Thus, efficient solar driven hydrogen evolution also requires efficient solar-driven oxygen evolution. The environment at a photoanode in water will be highly oxidizing which is severely detrimental to many semiconductors and precludes the use of numerous, otherwise promising, materials. We are working on developing surface chemistry that will protect oxidatively unstable surfaces.
Contact Professor Johansson for further research details or information about how to join this research team.
- O'Leary, L. E.; Johansson, E.; Brunschwig, B. S.; Lewis, N. S. (2010). Synthesis and Characterization of Mixed Methyl/Allyl Monolayers on Si(111) J. Phys. Chem. B in press.
- Johansson, E.; Hurley, P. T.; Brunschwig, B. S.; Lewis, N. S. (2009). Infrared Vibrational Spectroscopy of Isotopically Labeled Ethyl-Terminated Si(111) Surfaces Prepared Using a Two-Step Chlorination/Alkylation Procedure. J. Phys. Chem. C 113(34): 15239-15245.
- Johansson, E.; Zink, J. I. (2007). Nanostructured Silica Thin Films Self-Assembled with Electron Donors and Acceptors to Measure Electron Tunneling. J. Am. Chem. Soc. 129(46): 14437-14443.
- Angelos, S.; Johansson, E.; Stoddart, J. F.; Zink, J. I. (2007). Mesostructured silica supports for functional materials and molecular machines. Adv. Funct. Mater. 17(14): 2261-2271.
- Kickhoefer, V. A.; Garcia, Y.; Mikyas, Y.; Johansson, E.; Zhou, J. C.; Raval-Fernandes, S.; Minoofar, P.; Zink, J. I.; Dunn, B.; Stewart, P. L.; Rome, L. H. (2005). Engineering of vault nanocapsules with enzymatic and fluorescent properties. Proc. Natl. Acad. Sci. USA 102(12): 4348-4352.