Reports: UNI10 50094-UNI10: Order vs. Disorder: Does Pore Geometry Affect the Electrochemical Performance of Carbon Electrode Nanoarchitectures?

Justin C. Lytle, PhD, Pacific Lutheran University

Generous funding from the American Chemical Society Petroleum Research Fund (ACS PRF) during the 2009–2010 academic year was pivotal in my professional development as a young scientist at Pacific Lutheran University, a primarily undergraduate institution. This funding enabled my research group to continue our study of porous carbon nanomaterials that store electrochemical energy as double-layer capacitance. We hypothesized in February 2009 that the pore geometry of porous carbon nanoarchitectures is irrelevant to the magnitude of an electrode’s specific capacitance, because double-layer capacitance is directly proportional to an electrode’s electrifiable surface area alone. To address this hypothesis, my research group used ACS PRF funding throughout the 2009–2010 academic year to develop and optimize methods that fabricate and characterize two types of carbon nanomaterials: carbon inverse opal papers and carbon nanofoams. Both materials have comparable physico-chemical properties except for intentional differences in the periodicity of their pore networks.

This funding permitted my research group to make major progress during the past twelve months on a multi-step method that assembles carbon inverse opal paper electrodes. The inverse opal pore geometry comprises three-dimensionally interconnected, close-packed spherical macropores (pore diameters > 50 nm). In a typical preparation, we synthesize 250-nm polymer sphere colloids and deposit them as close-packed templates within the interfiber voids of carbon fiber papers. After infiltrating the periodic voids between template spheres with a dilute resorcinol-formaldehyde precursor, we subsequently cure and pyrolyze polymer-fiber composites into a carbonized inverse opal fabric. To the best of our knowledge, this is the first report of an inverse opal fabric.  This discovery is significant to the scientific community because it introduces mechanical flexibility into inverse opals, which have until now been formed as powders, thin films, and monoliths. Carbon inverse opal papers are at least ten times more conductive than conventional carbon inverse opal monoliths, and this is a clear advantage for applications in electronics and electrochemistry.

Likewise, I attribute the majority of our research progress to my ACS PRF funding because it allowed me to employ student researchers for up to 20 hours per month during the fall and January academic terms. Because of PRF funding, my undergraduate students had continuity from their summer research projects, and they seamlessly transitioned to electrochemically characterize both inverse opals and nanofoams during the fall and January terms. We adopted literature protocols in cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic cycling, and four-point conductivity measurements to assess the electrochemical properties of both nanomaterials. With ACS PRF funding, my students and I were able to collect enough quality data to present our findings at the 239th National Meeting of the American Chemical Society in March 2010. Without PRF support, my group’s research likely would have been backlogged by at least two months and the data that I illustrated in my presentation would have been incomplete and less compelling. As it turned out, my ACS talk was well-received by peers in my field, and this confirmed to me that my hypothesis, methods and results are scientifically reasonable. I am currently in the beginning stages of preparing a manuscript to publish our results.

Undergraduate students in my research group also benefited greatly from our ACS PRF funding. They were given hands-on experience with state-of-the-art nanomaterials that one would more likely encounter in a graduate school environment. Without question, their undergraduate research will open doors for them if they pursue graduate studies. At least one of my students has indicated a true passion for attending graduate school in chemistry, and I would not be surprised if she specialized in materials chemistry because she has thrived on the work in my group. The remainder of my students have also benefited from ACS PRF funding because they plan on applying the scientific skills that they honed in my research group to programs in medicine, dentistry, and forensics. Secondly, my students were afforded several months of hands-on electrochemistry training, which developed their knowledge of this often misunderstood field and helped them become proficient in making electrochemical measurements. Funding from ACS PRF also gave my students the chance to routinely work use a high-resolution scanning electron microscope at the University of Washington in Seattle to image our nanomaterials. My students now understand the general mechanisms that allow the microscope to function, what its capabilities are, and how best to acquire publication-quality images. Finally, the ACS PRF funds will support my students to travel to the 2011 Spring National Meeting of the ACS in Anaheim, CA, where they will give a poster and oral presentations. I aspire to list the four of them as co-authors on at least one future publication about their research findings.

As an important note, I will be seeking an extension of my ACS PRF funds because my Chemistry Department encouraged me to use large donations that prominent alumni recently gave to our program for undergraduate research. While a large portion of my allocated ACS PRF funds were not tapped for this fiscal cycle, I will seek an extension in my ACS PRF funding window so that I may fully utilize the funds according to ACS PRF’s extension guidelines.

 
Moving Mountains; Dr. Surpless
Desert Sea Fossils; Dr. Olszewski
Lighting Up Metals; Dr. Assefa
Ecological Polymers; Dr. Miller