Photochemical Reduction of CO2 Using Delafossite Oxides
- Type: Conference Presentation
- Conference Type: AIChE Annual Meeting
- Presentation Date: November 1, 2012
- Duration: 15 minutes
- Skill Level: Intermediate
- PDHs: 0.50
The photochemical reduction of CO2 in the presence of H2O to form CO, CH4 and other light gases with industrial value is an interesting approach for dealing with CO2 emissions. This approach can generate tangible revenue to help offset carbon capture and storage costs by generating a product stream with industrial demand from a CO2 feedstock. Delafossite materials of the general stoichiometry ABO2 are a new class of photocatalysts being considered for this application. Recent theoretical calculations have indicated that B-site alloying in these systems breaks the inversion symmetry of the crystal giving rise to symmetry forbidden optical transitions across the band structure of the material. B-site alloying can also be used to modulate the delafossite band structure to create new, low energy band gaps, as well as to align band edge positions for the photochemical redox reactions needed specifically for CO2 applications. The photochemical activity of CuAlO2, CuAl0.9Fe0.1O2, CuGaO2 and CuGa1-xFexO2 (x=0.05, 0.1, 0.15, 0.2) for the reduction of CO2 will be presented. The photoreduction of CO2 in the presence of H2O vapor using CuAlO2, CuAl0.9Fe0.1O2, CuGaO2 and CuGa1-xFexO2 produces CO with little evidence for other products such as H2 or hydrocarbons. The observed optical spectra will be compared to the theoretical band structure in these systems to better understand how B-site alloying can be used to control the optical activity of this material for photochemical applications. Additionally, the calculated band edge positions will be compared to CO2 reduction and H2O oxidation potentials to better understand the reaction products and yields observed experimentally.