Casey Laboratory

Greg finished his undergraduate at the University of Notre Dame in Indiana, where he did unergraduate research on uranium clusters with Peter C. Burns. He then moved to UC Davis as a graduate student working under both Profs. R. David Britt and William H. Casey. Greg had begun work to characterize the metal-oxygen coupling in dimeric manganese mu-oxo water oxidizing compounds using both EPR and 17O-NMR. Characterizing this coupling will give better insight into the role of the oxo bridges and the kinetics of water oxidation in the oxygen-evolving complex of photosystem II. Greg also worked on characterizing Co-Pi, a new cobalt-based water-splitting catalyst. He finished his PhD in 2012.

I am working under the guidance of Professors R. David Britt and William H. Casey to characterize a new cobalt-based water-splitting catalyst, Co-Pi. Inspired by the oxygen evolving complex of photosystem II (PSII), Co-Pi catalyzes the oxygen half of the water-splitting reaction, a key step in solar-energy harvesting. Likewise, Co-Pi can be interfaced with modern photovoltaic technology, analogous to how PSII is coupled to the light-harvesting P680 pigment. The electrons liberated in the water-splitting reaction can be used by a hydrogen-evolving catalyst, cheaply converting solar energy into potable H2-based fuel that can be stored indefinitely and later converted into electricity by a fuel cell. In our first paper published on this topic, I used electron paramagnetic resonance, a spectroscopy to look at the electronic structure of paramagnetic ions, to identify a rare Co(IV) species only present during and immediately after water splitting takes place. In soon-to-be-published studies, we characterize a synthetic inorganic model complex that approximates the structure of Co-Pi to gain insight into why it works so well. We are also beginning to look at the effects of different buffers on the catalyst system. Because this artificial photosynthetic system is based on and a structural relative to the oxygen evolving complex of PSII, insight we gain on this system and models of this system could have a major impact on our understanding of photosystem II.

2011

6. Panasci, A. F., McAlpin, J. G., Ohlin, C. A., Christensen, S., Fettinger, J. C., Britt, R. D., Rustad, J. R., Casey W. H. "Cooperation between bound waters and hydroxyls in controlling isotope-exchange rates", Geochim. Cosmochim. Acta, 2011, In Press. Link

5.McAlpin, J. Gregory; Ohlin, C. André; Surendranath, Yogesh; Nocera, Daniel G.; Casey, William H.; Britt, R. David "Electronic structure description of a [Co(III)₃Co(IV)O₄ cluster: A model for the paramagnetic intermediate in cobalt-catalyzed water oxidation" J. Am. Chem. Soc., 2011, 133, 15444-15452. Link

4.Gerkent, James B.; McAlpin, J. Gregory; Chent, Jaime Y. C.; Rigsby, Matthew L.; Casey, William H.; Britt, R. David; Stahl, Shannon S "Electrochemical water oxidation with cobalt-based electrocatalysts from pH 0-14: The thermodynamic basis for catalyst structure, stability and activity" J. Am. Chem. Soc., 2011, 133, 14431-14442. Link

3. Ohlin, C. André; Harley, Stephen J.; McAlpin, J. Gregory; Hockin, Rosalie K.; Mercado, Brandon Q., Johnson, Rene L.; Villa, Eric M.; Fidler, Mary Kate; Olmstead, Marilyn M.; Spiccia, Leone; Britt, R. David; Casey, William H. "Rates of water exchange for two cobalt(II) heteropolyoxotungstate compounds in aqueous solution", Eur. J. Chem. , 2011, 17(16), 4408-4417. Link

2010

2. McAlpin, J. Gregory; Surendranath, Yogesh; Dinca, Mircea; Stich, Troy; Stoian, Sebastian; Casey, William H.; Nocera, Daniel; Britt, R. D. "EPR Evidence for Co(IV) Species Produced During Water Oxidation at Neutral pH" J. Am. Chem. Soc., 2010, 132(20), 6882-6883. Link

2008

1. Forbes, Tori Z.; McAlpin, J. Gregory; Murphy, Rachel; Burns, Peter C. "Metal-oxygen isopolyhedra assembled into fullerene topologies" Angew. Chem. Int. Ed., 2008, 47(15), 2710. Link