Integrated CO2 Capture and Photocatalytic Conversion to Solar Fuels Using Multifunctional Materials

Wednesday, 8 October 2014: 11:00
Sunrise, 2nd Floor, Mars 1-4 (Moon Palace Resort)
L. Liu, J. Chen, and Y. Li (University of Wisconsin-Milwaukee)
Photocatalytic conversion of CO2 with H2O to solar fuels is a promising technology to recycle CO2, a major greenhouse gas. However, the CO2-to-fuel conversion efficiency is typically low, mainly due to the fast recombination of photo-excited electron-hole pairs and limited absorption of solar spectrum by the photocatalyst. Some scientific challenges that have been overlooked in the literature are the photocatalyst’s ability to adsorb, activate and dissociate CO2, as well as the adsorption/desorption kinetics on the catalyst surface.  To solve these problems, we have designed a new multifunctional material, porous microsphere MgO/TiO2 that performs as a hybrid adsorbent/photocatalyst, and we operated the CO2 photo-conversion temperature at around 150 oC.  The higher reaction temperature enhanced intermediate/product desorption, and the addition of MgO improves CO2 adsorption at the MgO-TiO2 interface, particularly in the presence of water vapor. This multifunctional material demonstrated a significantly enhanced and more stable activity than pure TiO2 for CO2 photoreduction to CO. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study was applied to identify surface intermediates and study the kinetics that is a critical factor governing the activity and stability of the photocatalyst. The effects of MgO morphology and dispersion on the TiO2 surface are also investigated.