EAGER: Development of Visible Light Driven Photocatalytic Nanocomposites for the Reduction of CO2 to Hydrocarbon Fuel

摘要将二氧化碳转化为合成燃料是一种极具吸引力的方法，如果这种转化过程与太阳能等可再生资源相结合的话。与费托合成碳氢化合物相比，光诱导二氧化碳还原导致形成能量丰富的燃料，如将CO2转化为CH4或更高的碳氢化合物，尚未得到充分的研究。在这种情况下，使用光催化半导体材料，如二氧化钛，是有希望的，因为易于光产生电荷载流子，促进涉及二氧化碳和水蒸气的表面反应。目前，这种光催化工艺的效率很低。二氧化钛（TiO2）广泛应用于光催化、水分解等领域。然而，它只能利用太阳光谱中的紫外线部分（不到总太阳光能量的4%），这导致该催化剂在利用太阳光能量方面的总效率较低。显然，使用TiO2光催化将CO2还原为碳氢化合物燃料（如甲烷、乙烷或甲醇）的关键挑战是利用阳光的可见光谱提高CO2的转化率。由于天然二氧化钛的高带隙导致的低转化率是一个限制，通过开发具有更高光还原位点的新型可见光活化光催化剂来改善这一问题。在EAGER资助下，pi将通过阴离子掺杂、封装、纳米壳/核配方和带隙裁剪程序设计和开发新型可见光活化光催化剂。初步结果表明，通过热化学和机械化学工艺对TiO2进行阴离子掺杂和带隙裁剪，除了具有较大的活性表面积外，还增强了TiO2在可见光区的光学吸收特性。从阳光和水中生产清洁液体燃料将有助于减少温室气体排放和石油进口。此外，该项目还将对教育产生重大影响，因为它将用于在塔斯基吉大学（HBCU）启动可再生能源研究培训的新领域。

AbstractSequestering 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.