Abstract
The design of highly efficient, non-biological, molecular-level energy conversion “machines” that generate fuels directly from sunlight, water, and carbon dioxide is both a formidable challenge and an opportunity that, if realized, could have a revolutionary impact on our energy system. Basic research has already provided enormous advances in our understanding of the subtle and complex photochemistry behind the natural photosynthetic system, and in the use of inorganic photo-catalytic methods to split water or reduce carbon dioxide-key steps in photosynthesis. Yet people still lack sufficient knowledge to design solar fuel generation systems with the required efficiency, scalability, and sustainability to be economically viable.
In the US Department of Energy (DOE) Energy Innovation Hub, the Joint Center for Artificial Photosynthesis, the speaker and his research group are developing an artificial photosynthetic system that will only utilize sunlight and water as the inputs and will produce hydrogen and oxygen as the outputs. They are taking a modular, parallel development approach in which the three distinct primary components-the photoanode, the photocathode, and the product-separating but ion-conducting membrane-are fabricated and optimized separately before assembly into a complete water-splitting system. The design principles incorporate two separate, photosensitive semiconductor/liquid junctions that will collectively generate the 1.7-1.9 V at open circuit necessary to support both the oxidation of H2O (or OH-) and the reduction of H+ (or H2O). The photoanode and photocathode will consist of rod-like semiconductor components, with attached heterogeneous multi-electron transfer catalysts, which are needed to drive the oxidation or reduction reactions at low overpotentials. This talk will discuss a feasible and functional prototype and blueprint for an artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously efficient, durable, scalably manufacturable, and readily upgradeable, including both the operational and technical scope of the JCAP Hub, as well as technical results towards this goal that has recently been developed at Caltech.
About the speaker
Prof Nathan Lewis received his PhD in Chemistry from Massachusetts Institute of Technology in 1981. He was faculty at Stanford University from 1981 to 1988. He joined the California Institute of Technology in 1988, and is currently George L. Argyros Professor of Chemistry. He has served as the Principal Investigator of the Beckman Institute Molecular Materials Resource Center at Caltech since 1992. He is also the Scientific Director and Project Co-Leader for Light Capture and Conversion of the US Department of Energy’s Energy Innovation Hub, the Joint Center for Artificial Photosynthesis.
Prof Lewis’ research interests include artificial photosynthesis and electronic noses. Research in his group focuses on photoelectrochemistry and chemical vapor sensing.
Prof Lewis received numerous awards including the Fresenius Award, the ACS Award in Pure Chemistry, the Orton Memorial Lecture Award, the Princeton Environmental Award and the Michael Faraday Medal of the Royal Society of Electrochemistry. He is currently the Editor-in-Chief of the Royal Society of Chemistry journal, Energy & Environmental Science. He has published over 300 papers.
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