Dr. Shane Ardo: Solar photochemistry at the energy–water nexus

 

Abstract: Greater thscreen-shot-2016-12-26-at-9-48-10-pman 10% of the global population does not have access to potable water. This number is expected to quadruple in the next 13 years, mostly due to children in developing nations. While the oceans contain a huge supply of water, it is not potable because it contains large amounts of salt, which is toxic to humans. This supply and demand scenario can be met with over a trillion U.S. dollars in capital investments in current state-of-the-art reverse osmosis plants and electricity grids; however, it also requires altruism because those that need the water most do not have the capital or infrastructure to inves
t in it. Therefore, there exists an urgent need for innovative technologies that can help generate nearly on trillion litres of potable water every day. My group is developing a new solar-energy-conversion technology that we think can help supply potable water to those people that demand it most.

Most bioinspired solar-energy-conversion technologies mimic Nature’s properties of light absorption, electronic charge separation, and electronic charge collection, where ultimately electrons make and break chemical bonds. My group is instead motivated by Nature’s ability to transduce photon energy into proton gradients. In my presentation I will report on my research group’s recent success in demonstrating ionic power generation through solar light harvesting with dye-sensitized ion-exchange membranes. Mechanistically, visible light was used to drive endergonic excited-state proton transfer from a covalent photoacid-modified ion-exchange membrane. Photoacid molecules convert the energy in light into a change in the chemical potential of protons via a weakening of a protic functional group on the photoacid, i.e. a decrease in its pKa. A cation-conductive membrane, i.e. Nafion, served as the selective contact for protons such that absorption of light resulted in photovoltaic action, i.e. a photocurrent and a photovoltage. As a model system for ion-channels in phase-segregated ion-exchange membranes like Nafion, nano-engineered dye-sensitized conical nanopores in poly(ethylene terephthalate) (1 – 108 pores/cm2) were investigated. Remarkably, in a region occupied by ~20 zeptoliters (~2 x 10-20 L) of aqueous electrolyte, electrochemistry and fluorescence microscopy were used to determine the photoacidity of the surface-bound dye molecules, which changed from the values found in bulk solution, likely as a result of surface charges in the confined nanopores. It is our hope that a technology based on our research can help alleviate some of the urgent global needs surrounding clean water scarcity.

Bio: Dr. Shane Ardo has been an Assistant Professor at the University of California, Irvine in the Department of Chemistry since 2013 and holds a joint appointment in the Department of Chemical Engineering and Materials Science. In 2016, Shane was named one of five inaugural Moore Inventor Fellows and was also the recipient of a Beall Innovation Award. He is the lead inventor on 5 patents and has co-authored over 30 peer-reviewed journal articles. Shane’s research interests are driven by the pursuit of understanding and controlling energy conversion mechanisms for applications in solar fuels devices, photovoltaics, solar seawater desalination, fuel cells, and redox flow batteries. His research group is supported by funding from the U.S. Department of Energy, U.S. National Science Foundation, Gordon and Betty Moore Foundation, and Beall Family Foundation. Shane obtained a B.S. Degree in Mathematics, with a minor in Computer Programming, from Towson University and subsequently worked as a software engineer, community college instructor, and high school teacher prior to attending graduate school. Shane obtained an M.S. Degree in Nutrition from the University of Maryland, College Park followed by M.A. and Ph.D. Degrees in Photo-Physical Inorganic Chemistry from the Johns Hopkins University, where he worked for Prof. Jerry Meyer. He then worked for Prof. Nate Lewis as a DOE-EERE Postdoctoral Research Awardee at the California Institute of Technology until 2013.

Shane tries to maintain a work–life balance. Notably, he has been an avid soccer player and soccer fan for most of his life, playing as a goalkeeper for Towson University’s Division I-A Men’s Soccer Team and trying out for a professional indoor soccer team in Cleveland, OH. Shane has also enjoyed playing roller hockey, ice hockey, and flag football, participated in other exciting events including starting a new chapter of a fraternity as its president, running with the bulls in Pamplona, Spain, working as an actor and model, running and completing the first annual Baltimore Marathon, and attending five consecutive World Cup Soccer Tournaments, and trained with athletes from the University of Maryland’s NCAA Champion Men’s Basketball Team and Baltimore’s Super Bowl Champion Ravens Football Team while working as a personal trainer and strength and conditioning coach. Shane met his wife, Jessica, in a soccer game, and has two absolutely amazing children.