SusChEM: Deep Photochemical Reduction of Carbon Dioxide to Methanol

美国国家科学基金会化学催化计划支持弗雷德里克M。MacDonnell和Norma S.德克萨斯大学阿灵顿分校的Tacconi博士合作开发了一类分子光催化剂，旨在将二氧化碳还原为甲醇。 来自化石燃料的能源虽然是当今经济的核心，但不是全球能源需求的可持续解决方案，并且在继续使用时可能会产生严重的环境后果。 从化石燃料中提取的液体运输燃料很难被替代，然而，将二氧化碳（一种温室气体）有效转化为液体燃料（如甲醇）的太阳能技术可以直接解决这个问题。 该研究小组正在使用成熟的钌多吡啶络合物作为发色团，因为它们具有稳定性，可调谐性和良好的物理特性。 这些分子与吡啶基催化剂偶联，以获得二氧化碳到甲醇的深度6电子还原。 值得注意的是，尽管使用均相过渡金属催化剂的二氧化碳电还原和光还原的所有进展，但还原仅限于双电子还原产物（一氧化碳或甲酸），而明显不存在更深的还原为甲醇或甲烷。 众所周知的钌发色团被用于提供概念验证结果，该结果在利用基于有机染料或地球上更丰富的元素的发色团之前建立反应机制。 光催化活性正在研究中的水（作为pH值的函数）和非水环境中，在存在和不存在的金属表面，并与各种电解质和中性改性剂，以促进所需的反应。 使用定制设计的光反应器筛选和询问光催化剂功能，并通过确定量子产率和催化转化率作为反应条件的函数来优化其催化效率。 这项研究的技术意义可能有助于开发碳中和燃料循环并生产一种只需要最少的基础设施改变即可采用的液体燃料。 这项研究福尔斯“SusChEM”计划，因为它利用非石油资源（即，二氧化碳）以产生液体燃料（甲醇）。 研究人员通过一些推广计划积极参与K-12教育，最值得注意的是通过开发和实施外部资助的“化学魔术秀”，通过科学学院的科学大使计划运行。自2008年举办以来，已有超过43，400名学生观看了“化学魔术表演”。

The NSF Chemical Catalysis Program supports the efforts of Professors Frederick M. MacDonnell and Norma S. Tacconi of the University of Texas at Arlington to develop a class of molecular photocatalysts designed to drive the reduction of carbon dioxide all the way to methanol. Energy derived from fossil fuels, while central to today's economy, is not a sustainable solution to global energy needs and has potentially severe environmental consequences upon continued use. Liquid transportation fuels derived from fossil fuels are difficult to replace, however solar technologies that efficiently convert carbon dioxide (a greenhouse gas) to liquid fuels (such as methanol), could directly address this problem. This research team is using well-established ruthenium polypyridyl complexes as chromophores because of their stability, tunability, and favorable photophysical properties. These molecules are coupled with pyridine-based catalysts to obtain a deep 6-electron reduction of the carbon dioxide to methanol. Notably, despite all the advances with carbon dioxide electro- and photo-reduction with homogeneous transition metal catalysts, reduction has been limited to the two-electron reduction products (carbon monoxide or formic acid) with deeper reduction to methanol or methane conspicuously absent. The well understood ruthenium chromophore is being used to provide proof-of-concept results that establish the reaction mechanism before chromophores based on organics dyes or more earth-abundant elements are utilized. Photocatalytic activity is being studied in both aqueous (as a function of pH) and non-aqueous environments, in the presence and absence of metallic surfaces, and with various electrolytes and neutral modifiers to promote the desired reaction. Photocatalyst function is screened and interrogated using custom designed photoreactors and their catalytic efficiency is optimized by determining quantum yield and catalytic turnover as a function of reaction conditions. The technical implications of this research may help develop a carbon-neutral fuel cycle and produce a liquid fuel that requires minimal infrastructure changes to adopt. This research falls under the "SusChEM" program as it utilizes non-petroleum based resources (i.e., carbon dioxide) to produce a liquid fuel (methanol). The investigators are actively involved in K-12 education through a number of outreach programs, most notably through the development and implementation of an externally-funded "Chemistry Magic Show" run through the Science Ambassadors program in the College of Science. Over 43,400 students have seen the "Chemistry Magic Show" since its inception in 2008.