TiO2 Nanotube-Quantum Dot Composites for Photocatalysis

随着绿色化学和节能变得至关重要，利用光和更好地利用阳光来影响化学变化的能力正变得越来越重要。各种晶型的二氧化钛(TiO2光催化剂)可能是研究最广泛的光催化剂材料。氧化钛纳米管(TNT)为下一代光催化剂的设计提供了独特的机会，将高纵横比、高比表面积和介孔性结合在一起。块状二氧化钛的带隙(锐钛矿型为3.2 eV)位于紫外线中，因此只有大约10%的太阳能量可以用于光催化过程。金属和非金属掺杂以及表面修饰是目前提高二氧化钛基光催化剂和光伏器件性能的策略。因此，除了控制TNTs的形貌外，TNTs的掺杂和表面修饰也是催化剂开发的一个重要方面。TNTs的一个独特特征是可以单独功能化的外表面和内表面。这些都是前所未有的复合纳米结构，可能会导致突破性的光催化。以下拟议的研究将涉及半导体纳米颗粒和薄膜修饰的二氧化钛纳米管的合成和表征，以及与环境污染和节能相关的光催化活性的评估。提出的活性的智力价值很明显，研究人员开始更多地将复合纳米材料和结构视为有吸引力的催化剂。TNTs令人兴奋的方面是能够分别对内表面和外表面进行修饰，这可能赋予其前所未有的催化活性。因此，有机会制备独特的杂化复合材料，而纳米棒或介孔颗粒是不可能的。初步结果表明，半导体量子点和薄膜可以被完全包裹在介孔中，或者只被涂覆在外表面。这项拟议的研究将描述用不同的半导体量子点、纳米棒和薄膜来装饰二氧化钛纳米管表面的策略。有机染料光降解的初步结果表明，与基准催化剂相比，其活性有了显著的提高。拟议研究的进展还可能导致我们在光伏等领域部署新技术。所提出的活性结果可能有助于确定光催化和水分解的新方向。拟议活动的更广泛影响该项目的更广泛影响包括许多任务，这些任务将导致将催化和新型纳米材料领域的研究和多层次教育结合起来。如果开发用于有机污染物和水转化的二氧化钛纳米管复合光催化剂的努力取得成功，那么我们预计短期内将对社会产生重大影响。可能受益于拟议活动的领域包括地下水解毒和国土安全，以及纳米催化、智能纺织品、传感器、过滤和节能。此外，与研究活动相吻合的还有很强的教育内容。拟议的研究涉及纳米科学的当代主题，学生在这个项目中获得的技能将加强他们在纳米技术、化学工程和材料化学领域的职业准备。除了有关纳米材料及其在环境和能源中的应用的研讨会和课程开发外，我们还寻求让所有级别的学生参与纳米材料及其在环境和能源中的许多令人兴奋的应用的研究。我们将参加NanoExplorers项目，在该项目中，学生们参与讨论、研讨会和实验/研究。我们还致力于将其他高中生的研究经验作为韦尔奇和克拉克基金会暑期计划的一部分，以及为贫困高中生提供的ACS项目种子。预计一名高中教师也可能参与这一项目。因此，我们预计这个催化和纳米技术项目也将通过教育我们的高中教师和学生来影响整个社区。

0854059Balkus, Kenneth J. The ability to use light and more preferably sunlight to affect chemical change is growing in importance as green chemistry and energy conservation become critical. The various polymorphs of titanium oxide (TiO2) are probably the most widely studied materials for photocatalysts. Titanium oxide nanotubes (TNT) provide the unique opportunity to combine the high aspect ratio, high surface area and mesoporosity in the design of next generation photocatalysts. The band gap for bulk TiO2 (3.2 eV for anatase) lies in the ultraviolet such that only about 10% of the sun's energy could be used in a photocatalytic process. Metal and non-metal doping as well as surface modification define the current strategy for enhancing the properties of TiO2 based photocatalysts and photovoltaic devices. Thus, in addition to controlling morphology, doping and surface modification of the TNTs is an important aspect of catalyst development. A unique feature of the TNTs is the outside and inside surfaces that can be functionalized separately. These are unprecedented composite nanostructures and potentially could lead to ground breaking photocatalysis. The proposed research below will address the synthesis and characterization of TiO2 nanotubes decorated with semiconductor nanoparticles and films as well as the evaluation of photocatalytic activity relevant to environmental pollution and energy conservation. Intellectual Merit of the proposed activity It is clear that researchers are starting to think more of composite nanoscale materials and structures as attractive catalysts. The exciting aspect of TNTs is the ability to separately modify the inside and outside surface which may impart unprecedented catalytic activity. Thus there is the opportunity to prepare unique hybrid composites not possible with nanorods or mesoporous particles. Preliminary results show that semiconductor quantum dots and films can be exclusively encapsulated in the mesopores or coated on just the outer surface. The proposed research will describe the strategies for decorating the surfaces of TiO2 nanotubes with various semiconductor quantum dots, nanorods and films. Preliminary results for the photodegradation of organic dyes indicate dramatic improvements in activity relative to benchmark catalysts. Progress on the proposed research could also result in deployment of our new technology in areas such as photovoltaics. The results from the proposed activity may serve to define new directions in photocatalysis and water splitting. The broader Impacts of the proposed activity The broader impacts of this project include numerous tasks that will lead to the integration of research and multilevel education in the area of catalysis and novel nanomaterials. If the proposed effort to develop TiO2 nanotube composite photocatalysts for the conversion of organic pollutants and water is successful, then we anticipate that the near term impact on society will be significant. Probable areas that will benefit from the proposed activity include ground water detoxification and homeland security as well as nanocatalysis, smart textiles, sensors, filtration and energy conservation. Additionally, a strong educational component will coincide with the research activities. The proposed research addresses contemporary topics in nanoscience and the skills acquired by students during this project will enhance their preparation for careers in nanotechnology, chemical engineering and materials chemistry. In addition to seminars and course development on nanomaterials and their applications in environment and energy, we seek to engage students at all levels in the study of nanomaterials and their many exciting applications in environment and energy. We will participate in the NanoExplorers program where students participate in discussions, workshops, and experiments/research. We are also committed to other high school student research experiences as part of the Welch and Clark Foundations summer programs as well as ACS Project SEED for disadvantaged high school students. It is anticipated that a high school teacher may be involved in this project as well. As such we anticipate that this project in catalysis and nanotechnology will also impact the community at large by educating our high school teachers and students.