Sequestering carbon dioxide by conversion into synthetic fuels can be an immensely attractive approach if the conversion process is coupled with a renewable resource such as solar energy. Photoinduced carbon dioxide reduction leading to the formation of energy rich fuels, such as conversion of CO2 to CH4 or higher hydrocarbons has not been adequately studied as compared with the Fischer-Tropsch synthesis for hydrocarbons. In this context, use of photocatalytic semi-conducting materials such as titania is promising due to the ease of photogeneration of charge carriers that facilitate surface reactions involving CO2 and water vapor. At the present time, the efficiency of such photocatalytic processes is very low.
Titanium dioxide (TiO2) is widely used in many photocatalytic, water splitting applications. However, it can only utilize the ultraviolet portion of the solar spectrum (less than 4% of the total sunlight energy), which results in low total efficiency of such catalyst in the sunlight energy utilization. Apparently, a critical challenge in using TiO2 for photocatalytic reduction of CO2 to hydrocarbon fuels such as methane, ethane or methanol has been the enhancement of CO2 conversion rates using the visible spectrum of sunlight. Low conversion rates due to the high band gap of native titania is one limitation, which gets improved by developing novel visible light activated photocatalysts having higher photo-reductive sites for the hydrocarbon fuel formation.
Under this EAGER grant, PIs will design and develop novel visible light activated photocatalysts by anion doping, encapsulation, nanoshell/core formulation, and band gap tailoring procedures. Preliminary results have shown that both anion doping and band gap tailoring of TiO2 via thermochemical and mechanochemical processes thus enhances the optical absorption characteristics in the visible light region in addition to the large active surface area.
Production of clean liquid fuel from sunlight and water will help reduce the greenhouse gas emissions and petroleum imports. Additionally, this project will also have a substantial educational impact, as it will be used to start a new area of renewable energy research training at Tuskegee University, an HBCU.
