Closing of the photosynthetic cycle of water oxidation and carbon dioxide reduction on the shortest possible length scale the nanoscale offers the advantage of minimizing efficiency degrading ion transport processes and of chemical side reactions.
Square inch sized arrays of cobalt oxide-silica core-shell nanotubes offer a design for scalable artificial photosystems in which the cycle of CO2 reduction by H2O is closed on the nanoscale under membrane separation while products are separated across the continuum of length scales from nanometers to centimeters and beyond. A critical ingredient is a 2 nm silica membrane with embedded molecular wires for controlled charge transfer that also enables proton transport between the H2O oxidation and CO2 reduction environments.
Emphasis of the discussion will be on core-shell nanotube fabrication, the understanding of charge transfer across the various interfaces of the core-shell units, and of catalytic mechanisms of CO2 reduction at Cu clusters and H2O oxidation at metal oxide by time-resolved optical and transient ATR FT-IR spectroscopy. Ultrathin silica membranes enable electronic coupling of other types of incompatible catalytic environments on the nanoscale, as will be shown for integration of inorganic with microbial catalysts in nanobiohybrids.