(685a) Photochemical Reduction of CO2 Using Delafossite Oxides | AIChE

(685a) Photochemical Reduction of CO2 Using Delafossite Oxides


Lekse, J. - Presenter, US DOE, National Energy Technology Laboratory
Lewis, J. P., West Virginia University
Underwood, M. K., West Virginia University

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.