Princeton ACS Meeting Announcement

Princeton ACS Section Dinner Meeting

Monday, November 19, 2012

our guest speaker will be

Professor Charles Dismukes
Department of Chemistry and Chemical Biology, Rutgers University, Piscataway NJ

"Solar Fuels from Artificial Photosynthesis: How Biology has Informed Materials Science"

Abstract

Future human populations cannot survive on Earth without developing renewable energy. Hydrogen is the source of all practical fuels, whether as H2 gas or hydrocarbons, and water is its only globally available renewable feedstock. Three limitations to storing solar energy as hydrogen-derived fuels from water are: 1) need to replace noble metals as catalysts to split water into its elements; 2) lowering both the intrinsic electrochemical inefficiencies for conversion (catalyst over-potentials) and the extrinsic inefficiencies for matching the electrical source to the reactions (transformers), and 3) design of low cost "disposable" electrolyzers and solar cells. I will discuss new solutions to items 1 and 2 emerging from R&D.

Nature has already solved problem (1) for solar-to-fuel energy conversion in oxygenic phototrophs. However, materials scientists working on catalysts are largely unaware of nature's principles. These organisms all use a cubical calcium/manganese-oxo cluster to split water, MnO[Mn3CaO4]. After summarizing the principles used by natural photosynthetic organisms to oxidize water, I shall illustrate five examples of structurally well-characterized, bioinspired, materials that we have made, that illustrate these principles. Organometallic metal-oxo cubanes, containing Mn4O4- and Co4O4- cores surrounded by organic ligands as templating scaffold, share structural homology to the photosynthetic catalytic site and were among the first catalysts emulating nature's winning design. Elimination of the unstable organic scaffolding is absolutely essential for practical catalysts for water splitting. This need led us to search for inorganic materials that could be found naturally or tailored synthetically to adopt the bionspired blueprint found in photosynthesis, while exhibiting the appropriate redox chemical properties. To test the importance of the bioinspired cubical structure, we synthesized 8 of the 30 predicted structurally distinct polymorphs of manganese and oxygen, MnxOy. This revealed that, like the photosynthetic core, only those polymorphs possessing cubical Mn4O4 building blocks and long (weak) Mn-O bonds are catalysts for water oxidation. The structural advantage of the bioinspired cubical topology for catalysis of water oxidation is clearly illustrated by members of the binary spinels, compositionally AB2O4. For example, I will illustrate water oxidation activity of two distinct structural polymorphs of LiCoO2. The cubic "spinel" polymorph is ~100 times more active than the thermodynamically more stable "layered" polymorph, commonly used in batteries. Comparison of this material as electro-catalyst in alkaline electrolyzers reveals it equals or outperform iridium and platinum catalysts in independent tests. This material is licensed for development and may prove a suitable substitute in future commercial electrolyzers.

Biography

Professor G. Charles Dismukes is Professor of Chemistry and Chemical Biology at Rutgers University, and a member of the Waksman Institute and the Biochemistry and Microbiology Departments. His research interests focus on biological and chemical methods for renewable solar-based fuel production, photosynthesis, metals in biological systems and tools for investigating these systems. His published works describe the biology and chemistry of oxygen production in natural photosynthetic systems, the synthesis and characterization of bioinspired catalysts for renewable energy production, and the use of microorganisms as cell factories for the production of bio-fuels from renewable sources. Chuck earned his BS in chemistry, with high honors, from Lowell Technological Institute, in Lowell, Massachusetts, and his PhD in chemistry from the University of Wisconsin, Madison. After a postdoctoral appointment at the University of California-Berkeley, Chuck joined the faculty of the chemistry department at Princeton University in Announcement of the Princeton ACS Section1978. He rose through the ranks to appointment as full Professor of chemistry in 1991. In 2010, Professor Dismukes transferred to Emeritus status at Princeton, and was lured to our northern neighbor, where he continues his research on photosynthesis and renewable solar-based fuel production as a member of the Rutgers faculty.

Reservations:

The meeting will be held in Frick Laboratory, Princeton University. The social mixer will begin at 5:30 pm in the CaFe area of Taylor Commons. The lecture will be held in the Auditorium at 6:30 pm followed by dinner in Taylor Commons (CaFe area). Frick Laboratory is located at the east end of the pedestrian bridge on Washington Rd, adjacent to the Weaver Track and Field Stadium.

Parking is available in Lot 21, corner of Faculty Road and Fitzrandolph Road or other lots along Ivy Lane (see www.princeton.edu/main/visiting/ for other parking options). The seminar is free and open to the public. Reservations are required for dinner, which is $20 ($10 for students). Please contact Louise Lawter at louise.lawter@gmail.com or 215-428-1475 by September 26 to make reservations. Reservations must be canceled no later than October 1 to avoid being billed for the dinner.