Photocatalytic Reduction of CO2 with H2O By Engineered TiO2 Nanocomposites

Wednesday, October 14, 2015: 10:30
104-B (Phoenix Convention Center)
Y. Li (Texas A&M University) and L. Liu (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 sunlight by wide band-gap photocatalysts like TiO2. In addition, some scientific challenges have been overlooked including the photocatalyst’s ability to adsorb CO2 and the adsorption/desorption kinetics on the catalyst surface. To promote charge transfer, visible light response, and CO2 adsorption and activation, we have engineered a series of TiO2 nanocomposites including Cu/TiO2, oxygen deficient TiO2, TiO2 nanocrystals with mixed exposed facets, porous microsphere MgO/TiO2, and nano-TiO2 dispersed on MgAl-layered oxide materials. Photocatalytic CO2 reduction experiments have been conducted under UV and visible light irradiation, respectively, with CO and CH4 being the major products. Furthermore, we have compared the CO2 adsorption and reduction intermediates and reaction kinetics at near room temperature and near flue gas temperature (~150 oC), using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The higher reaction temperature enhanced intermediate/product desorption, and the addition of basic materials (MgO and MgAl-LDO) improves CO2 adsorption particularly in the presence of water vapor, thus enhancing the catalytic activity and stability of the photocatalyst.