Controlling Energy Distribution Pathways in Designer Photocatalysts for Efficient Polymer Synthesis

在化学系化学催化项目的支持下，撒迦利亚A。Page和Sean T.德克萨斯大学奥斯汀分校的罗伯茨正在研究可见光和近红外光吸收染料分子的化学结构如何影响它们以节能方式催化塑料增材制造的能力。传统的基于光的制造依赖于使用仅在高能紫外（UV）光下操作的染料。这种对UV光的依赖是能量密集型的，并且由于UV光的低穿透深度及其诱导光损伤的可能性而限制了可以生产的材料的功能。受资助的研究团队旨在通过合成由地球丰富的元素组成的新染料分子来克服这一限制，并检查这些所谓的“光催化剂”有效收集可见/近红外（IR）光中所含能量的能力，以推动化学反应。这些基本的努力预计将以可承受的价格增加基于光的制造的可及性，这对涂层，微电子和3D打印等技术具有直接影响。该项目的更广泛影响将扩展到为跨学科化学的本科生和研究生提供新的培训机会，活动范围从化学合成到基于激光的光谱表征。此外，Page和Roberts还将在UT Austin和Austin Community College的教育项目之间架起桥梁，为学生创造一个通过实践研究机会分享知识和互动的渠道，以提高STEM的多样性。（科学、技术、工程和数学）。根据该奖项，Page和Roberts的UT-Austin合作团队的首要目标是开发具有生态意识的光催化剂，从可见光到近红外光，其效率和选择性超出了我们目前的工业黄金标准紫外光的能力。为此，将处理三个目标。第一个涉及建立无重原子光催化剂（例如，不含有毒卤素或昂贵金属的那些）和它们通过长寿命自旋三重态诱导聚合的能力。第二个目的是鉴定能够吸收多种不同颜色的光并使用该独特的双带吸收性质来驱动正交化学转化（即，波长选择性催化）。第三个目标是通过基于三重态聚变的光子上转换将更透明的低能量可见/近红外光子转换为高能量光子，从而在UV不透明材料中驱动快速光聚合。每个目标都将新型染料分子的合成与超快光谱表征相结合，以创建一个知识闭环，旨在加速光催化剂优化。如果成功的话，这项工作可能会产生重大的科学影响，因为人们对建立更有效的方法来收集从近红外到可见光的能量以驱动化学反应有很大的兴趣。这个奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

With the support of the Chemical Catalysis program in the Division of Chemistry, Zachariah A. Page and Sean T. Roberts of The University of Texas at Austin are studying how the chemical structure of visible and near-infrared light absorbing dye molecules influences their ability to catalyze the additive manufacturing of plastics in an energy-efficient manner. Traditional light-based manufacturing relies on the use of dyes that operate only with high-energy ultraviolet (UV) light. This reliance on UV light is both energy-intensive and limits the functionality of materials that can be produced due to the low penetration depth of UV light and its potential to induce photodamage. The funded research teams aim to overcome this limitation by synthesizing new dye molecules comprised of earth-abundant elements and examining the ability of these so-called 'photocatalysts' to efficiently harvest the energy contained in visible/near-infrared (IR) light to power chemical reactions. These fundamental efforts are anticipated to increase the accessibility of light-based manufacturing at an affordable price, which has direct implications in technologies such as coatings, microelectronics, and 3D printing. The broader impacts of the project will extend to providing new training opportunities for both undergraduate and graduate students in interdisciplinary chemistry with activities ranging from chemical synthesis to laser-based spectroscopic characterization. Moreover, Page and Roberts will bridge educational programs at UT Austin and Austin Community College to create a channel for students to share knowledge and interact via hands-on research opportunities in an effort to improve diversity in STEM (science, technology, engineering and mathematics).Under this award, the UT-Austin collaborative team of Page and Roberts has as its overarching goal the development of eco-conscious photocatalysts that can harvest low-energy, visible-to-near infrared light with efficiency and selectivity that extend beyond our current capabilities with UV light, the industrial gold standard. To this end, three aims will be addressed. The first involves the establishment of a quantitative correlation between the structure of heavy-atom free photocatalysts (e.g., those without toxic halogens or expensive metals) and their ability to induce polymerization via long-lived spin-triplet states. The second aim is to identify individual dyes capable of absorbing multiple different colors of light and using that distinct, dual-band absorptive property to drive orthogonal chemical transformations (i.e., wavelength-selective catalysis). The third aim seeks to drive rapid photopolymerizations in UV-opaque materials by converting more transparent low energy visible/near-infrared photons into high-energy ones via triplet fusion-based photon upconversion. Each aim combines the synthesis of novel dye molecules with ultrafast spectroscopic characterization to create a closed-loop of knowledge with the aim of accelerating photocatalyst optimization. If successful, this work could have significant scientific broader impacts as there is great interest in establishing more efficient methods of harvesting energy from near IR to visible light to drive chemical reactions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.