468204 Rational Design of Catalytic Sites for Energy Applications

Sunday, November 13, 2016
Continental 4 & 5 (Hilton San Francisco Union Square)
Timothy Van Cleve, Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO


The rapidly increasing global demand for energy coupled with large population growth necessitates the development of increasingly efficient systems for utilizing our finite energy and chemical resources. While no single approach will solve these complex issues, I strongly believe that catalysts have an important role to play in addressing these challenges. Our society is already heavily reliant on these materials to produce the chemicals that we need to sustain our lifestyles. Catalysts are incredible because of their ability to facilitate selective chemical transformations while converting between chemical, thermal, radiant, and electrical forms of energy. Coupling catalytic systems with renewable energy sources presents a unique opportunity to regenerate useful high value chemicals from low value feed stocks like CO2 and H2O.

In order to develop these technologies, it is vital to understand the pathway through which these chemical transformations proceed and how catalytic systems respond to different energetic and environmental stimuli. It is also vital to identify key characteristics of active, stable, and selective catalysts to enable the design of materials with optimal sites for a particular reaction. I have implemented this strategy in my academic pursuits as a PhD student and postdoctoral researcher.

Research Interests:

As faculty I plan to leverage my past research experience to improve catalytic performance for various chemical, electrochemical, and photochemical applications. My efforts will focus on the design of cheap, active, selective, and stable catalysts for carbon and nitrogen fixation, renewable H2generation, and selective upgrading of low-value oxygenates into important fuel and chemical feedstocks. I anticipate closely collaborating with theoreticians and other experimental specialists to decipher the true nature of catalytic sites under reaction conditions. With this information, structure-property relationships can be develop to give further insight to the field.

Research Experience:

Over the course of my graduate studies under Prof. Suljo Linic, we have investigated how geometric and chemical manipulations of catalytic sites influence overall catalytic performance. Specifically, we focused on understanding how changing the size, shape, and composition of Ag and Pt alloy electrocatalysts affects their activity towards the oxygen reduction reaction (O2+4H+/e-→2H2O, ORR) in alkaline and acidic electrolytes. First, kinetics studies of the oxygen reduction mechanism on these surfaces allowed us to identify key chemical descriptors (like OOH or OH adsorption energies) that are correlated with catalytic activity. We then utilized quantum chemical calculations to determine how these descriptors could be selectively influenced in platinum based catalysts through perturbations such as alloying or inducing geometric strain. After identifying promising catalysts, we developed sophisticated synthesis strategies to prepare these materials. We then tested their activity, with rigorous experimental protocol allowing us to obtain valid kinetic rates from the observed rates, and found that improved activity was achieved. Finally, we performed extensive in situ and ex situ characterization to confirm both that the atomic structure of the electrocatalyst matches that of our model and that the observed activity enhancement is a direct result of the improved key chemical descriptors of this particular nanostructure.

As a postdoctoral researcher working in Prof. Will Medlin group, I have focused on controlling rates and product selectivity for various thermochemical processes (such as CO oxidation, epoxidation, alcohol dehydration, and hydrodeoxygenation of phenolics) by manipulating the relative abundance and accessibility of different catalytic sites. Furthermore, the addition of chemical promoters to metal, support, or interfacial sites has been another method for altering the material flux through particular chemical pathways.

Teaching Interests:

My preference would be to teach chemical kinetics and reactor design because it closely aligns with my research background and extensive teaching experience. At Michigan, I served as a graduate teaching assistant (TA) for a graduate-level electrochemistry elective course (~70 students) as well as graduate chemical kinetics (~25), developing and evaluating homework and exam questions in addition to administering the course website and hosting review sessions. During my final year at UM, I was a Graduate Student Teaching Fellow for the undergraduate chemical reactor design course (~170). I was responsible for preparing course materials, managing personnel, and lecturing a 1/3 of the classes. Additionally, I am open to developing a graduate level elective course describing the fundamentals of catalyst design, which would be of particular interest to undergraduate and graduate students. Lastly, I have much experience as a mentor to both undergraduate and graduate students during my doctoral and postdoctoral research.

Extended Abstract: File Uploaded