September 9
@
4:00 PM
–
5:00 PM
Harry Atwater
Department of Applied Physics and Materials Science
California Institute of Technology
Pasadena, California
Design of Materials and Devices for Carbon Dioxide Capture and Conversion using Sunlight
Over the next two decades, science advances will be needed to enable scalable technologies for i) direct capture of dilute CO2 at the gigaton scale as well as ii) CO2 reduction to fuels, chemicals, and materials, powered by renewable energy or directly by sunlight. I will discuss materials and device advances needed for a promising capture approach, a scalable energy-efficient route to direct ocean capture of CO2, via an electrochemical pH swing. This scheme utilizes bipolar membrane electrodialysis to create the pH swing required to capture CO2 drawn down into the ocean in the form of dissolved inorganic carbon. I will also explore approaches for directly generating liquid solar fuels from carbon dioxide, sunlight, water. This requires new photocatalysts and thermocatalytic structures to facilitate transfer of electrons, protons, and reactants, to selectively yield multi-carbon products at semiconductor photoelectrode surfaces and catalytic sites. Two tandem reaction schemes for liquid solar fuel generation from CO2 will be discussed: i) a three-terminal tandem photoelectrode with two monolithically integrated but distinct catalytic centers operating at independent potentials to yield products via a cascaded reaction sequence, and ii) a tandem photoelectrochemical/solar thermocatalytic cascade that uses electrochemically synthesized ethylene, carbon monoxide and hydrogen as intermediates to yield multi-carbon products (butene, hexene, and heavier hydrocarbons) synthesized via solar-driven thermocatalytic reactions.