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，德克萨斯大学奥斯汀分校的Zachariah A.Page和Sean T.Roberts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的方式催化塑料添加剂制造的能力。传统的以光为基础的制造依赖于染料的使用，这些染料只在高能紫外线(UV)下工作。这种对紫外光的依赖既是能源密集型的，又由于紫外光的穿透深度较低而限制了可生产的材料的功能，而且它可能会导致光损伤。受资助的研究团队旨在克服这一限制，方法是合成由地球上丰富的元素组成的新染料分子，并检查这些所谓的“光催化剂”有效地获取可见光/近红外(IR)光中包含的能量以推动化学反应的能力。这些根本性的努力预计将以负担得起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通过从化学合成到基于激光的光谱表征等活动，为本科生和研究生提供跨学科化学的新培训机会。此外，佩奇和罗伯茨将在德克萨斯大学奥斯汀分校和奥斯汀社区学院的教育项目之间架起桥梁，为学生创造一个分享知识和通过动手研究机会进行互动的渠道，以努力提高STEM(科学、技术、工程和数学)的多样性。在这个奖项下，佩奇和罗伯茨的德克萨斯大学奥斯汀合作团队将开发具有生态意识的光催化剂作为其首要目标，这种催化剂可以获取低能量、可见光到近红外光，其效率和选择性超出了我们目前利用紫外光的能力，紫外光是工业的黄金标准。为此，将实现三个目标。第一个涉及建立无重原子光催化剂(例如，那些没有有毒卤素或昂贵金属的光催化剂)的结构与它们通过长寿命自旋三重态诱导聚合的能力之间的定量关联。第二个目标是识别能够吸收多种不同颜色光的单独染料，并利用这种独特的双波段吸收特性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，将更透明的低能可见光/近红外光子转化为高能光子，从而推动紫外光不透明材料的快速光聚合。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，以创建一个知识闭合环，目的是加速光催化剂的优化。如果成功，这项工作可能会产生重大的科学和更广泛的影响，因为人们对建立从近红外到可见光的更有效的能量收集方法以驱动化学反应非常感兴趣。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.