(385b) Photocatalytic Core-Shell Nanotube Array Converting Carbon Dioxide and Water to Fuels

Coupling H2O oxidation with CO2 reduction under membrane separation at the nanoscale is a critical design feature of natural photosynthesis for minimizing efficiency-degrading processes, in particular ion transfer resistance losses and unwanted reactions. To incorporate the feature into an artificial photosystem, we have developed square inch sized arrays of Co3O4-SiO2 core-shell nanotubes. As Figure 1 shows, each tube is able to accomplish the complete photosynthetic cycles, while spatially separating the incompatible oxidation and reduction environments on all length scales from nano to macro.

In-situ monitoring by electrochemical, optical, infrared, and mass spectroscopy plays a central role to demonstrate and optimize the photocatalytic performance of the nanotube array. To be more specific, electrochemical and optical spectroscopy establishes charge-carriers transfer mechanism through the nanotube wall, in-situ infrared spectroscopy illuminates how Ag nanoclusters photo-deposited outside the tubes serve as catalytic sites for visible light-driven CO2 reduction to CO, and mass spectroscopy allows to quantify O2 evolution from visible light-driven water oxidation inside the tubes.