(446d) CO2 Photoreduction by Nanostructured Composite Photocatalytic Materials Synthesized by a Furnace Aerosol Reactor System

Increasing anthropological emission of greenhouse gases (GHG) into the atmosphere is widely recognized to be the primary cause of global warming. In particular, carbon dioxide (CO₂) released from fossil fuel combustion is the major contribution to this phenomenon. CO₂ mitigation can be realized by efficient capture techniques which are energy intensive and costly. Recent innovations have made the use of photocatalytic approaches a potentially promising alternative for CO₂ conversion. The process can be applied for converting CO₂ to carbon-contained energy bearing compounds, such as carbon monoxide, methane, and ethanol.

The presentation will describe aerosol methodologies for synthesis of nanostructured composite materials for use in light activated carbon dioxide reduction. Nanocolloidal silica supported copper doped titania (Cu-TiO₂-SiO₂) mesoporous particles were directly synthesized by a template-free furnace aerosol reactor (FuAR). Aqueous suspensions of nanosized TiO₂ and SiO₂ colloids and copper nitrate solution were used as precursors. The size, crystallinity, bandgap, and surface area/pore size of the particles properties were tailored by manipulating the precursor concentration, stoichiometric ratio, and temperature, which were characterized by means of SEM, TEM, XRD, UV-VIS, and nitrogen physisorption measurements. CO₂ reduction was conducted inside a home-made quartz reactor under illumination of UV light followed by GC analysis. The results revealed that the particles were submicron-sized mesoporous spheres with average pore sizes from 20 ? 30 nm, having optimal molar percentages of TiO₂ and Cu to the whole particle of 2% and 0.01%, respectively, at which a high CO₂ conversion efficiency, i.e. CO yield of approximately 20 micromol/g-TiO₂/hr was achieved. It should be noted that these mesoporous catalyst particles were obtained without using any templates within several seconds, which avoids contamination and reduces cost. Other materials such as Bi-V and Bi-Ti complexes for the reduction of carbon dioxide will also be discussed.