CBE Seminar (ZOOM): Recipes for Converting Water into a Solar Cell

Abstract: Water is a protonic semiconductor that is doped through addition of salts of H+ or OH–. To fabricate a diode out of water, dopant counterions must be fixed in place. My group has realized protonic diodes using hydrated porous polymer scaffolds containing covalently bound Brønsted–Lowry acidic or basic functional groups, and using frozen aqueous solutions of mineral acids or alkali bases as solid ice. Diode properties were measured in electrochemical cells fabricated as membrane-electrode assemblies, where reversible H2 redox chemistry was used to transduce changes in protonic electrochemical potentials into electronic electrochemical potentials, and vice versa. Moreover, through dye sensitization using photoacid molecules, we demonstrated purely protonic photovoltaic action, but where the observed polarity of the photovoltage was opposite of that observed in traditional electronic solar cells. Using simulations based on mass continuity, mechanistic details of this novel photochemical process are ongoing. Our efforts are helping to form the fundamental framework for new devices and functions that benefit from purely ionic transport.

Bio: Ardo obtained a bachelor's degree in mathematics with a minor in computer programming from Towson University. Prior to earning graduate degrees, he worked as a software engineer, community college instructor and high school teacher, and tried out for a professional indoor soccer team. He obtained a master's degree in nutrition from the University of Maryland, College Park, followed by M.A. and Ph.D. degrees in photophysical inorganic chemistry from the Johns Hopkins University, where he worked for Professor Jerry Meyer. He then worked for Professor Nate Lewis as a DOE–EERE postdoctoral researcher at the California Institute of Technology until 2013. Since that time, Ardo has been an assistant professor (2013-2019) and now an associate professor at UC Irvine in the Department of Chemistry and holds courtesy joint appointments in the Departments of Chemical & Biomolecular Engineering and Materials Science & Engineering. His group studies photochemistry, with the aim of understanding and controling the kinetics and mechanisms of reactions at interfaces. They do this by designing, synthesizing, characterizing and modeling asymmetric molecule-material structures for practical applications in desalination, atmospheric water harvesting, solar fuels devices, photovoltaics, fuel cells, electrolyzers and redox flow batteries. In 2016, Ardo was named one of five inaugural Moore Inventor fellows. He is also a recipient of a DOE Early Career Research Award and a Beall Innovation Award, and was named a Sloan Research fellow, a Cottrell Scholar, a Kavli fellow, and a Scialog fellow. He has given over 100 invited talks, including at the National Academy of Sciences Distinctive Voices Lecture Series, the 2017 Resnick Institute Young Investigators Symposium and Apple’s Membrane R&D Division. His research group is also supported by funding from the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy, the U.S. Department of Defense’s Army Research Office, Nissan Chemical Corp., and collaborative projects funded by Research Corporation for Science Advancement and UC Irvine’s Research Seed Funding Program. His research group is also part of the recently announced DOE Energy-Water Desalination Hub.