Membranes are used as separators in photoelectrochemical cells that convert sunlight into chemicals such as H2 and CO2 reduction products. Their purpose is to conduct ions while blocking crossover and reoxidation of molecular products. The design and systems models of these membranes requires knowledge of their performance and properties during the diurnal cycle, when light intensity and hence permeant concentrations change continually. Membrane theory has not been developed for this situation, so we are constructing reaction-diffusion models to gain an understanding of how non-steady-state permeation works. In this talk I will introduce the requirements for solar fuels systems, and describe a combined experiment-simulation-theoretical investigation of time-dependent permeation through rubbery and glassy polymer membranes. The simulations are multiscale, linking nanoscale to macroscale in space and time, and do not use adjustable parameters. This allows validated models to be predictive, and provides a framework for mechanism discovery. Some insights to physical processes that are not well studied in the literature but appear to be important will be described.
Lawrence Berkeley National Laboratory
Dr. Houle is Deputy Director for Science and Research Integration of the Joint Center for Artificial Photosynthesis, and Senior Scientist in the Chemical Sciences Division at Lawrence Berkeley National Laboratory. Her scientific interests are in the areas of mechanisms of surface, thin film and aerosol chemical transformations, particularly at the nanoscale, investigated using both experimental and computational techniques. She received the BA from the University of California at Irvine and the PhD from the California Institute of Technology, both in chemistry. Prior to her current appointment she was a postdoctoral fellow at LBNL and the UC Berkeley Chemistry Department, Research Staff Member in the IBM Research Division in San Jose, California, Manager of Materials Development at InVisage Technologies, a startup company making nanoparticle-based image sensors, and Director of Strategic Initiatives in the Chemical Sciences Division at LBNL. She has received numerous awards including the 2009 American Vacuum Society John A Thornton Memorial Award and Lecture, the 1999 American Institute of Chemical Engineers Northern California Section Research Project of the Year, and the 1998 IBM Environmental Affairs Excellence Award. She is a Fellow of the American Physical Society and Fellow of the AVS, and member of the American Chemical Society and the Materials Research Society. She has been active in professional service, and is currently Past Chair of the APS Panel on Public Affairs. She has over 140 publications and 28 US patents, and is co-author of the open-access stochastic reaction-diffusion simulation code Kinetiscope.