TiO2 Nanotube-Quantum Dot Composites for Photocatalysis

[854059]随着绿色化学和节能变得至关重要，利用光，尤其是阳光来影响化学变化的能力正变得越来越重要。各种多晶型的氧化钛（TiO2）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结合高宽高比、高表面积和介孔的独特机会。大块TiO2的带隙（锐钛矿为3.2 eV）位于紫外线中，因此只有约10%的太阳能量可用于光催化过程。金属和非金属掺杂以及表面改性确定了当前增强TiO2基光催化剂和光伏器件性能的策略。因此，除了控制tnt的形貌外，掺杂和表面改性是催化剂发展的一个重要方面。tnt的一个独特之处在于它的内外表面可以分别被功能化。这些是前所未有的复合纳米结构，可能会导致突破性的光催化。下面的研究将涉及半导体纳米颗粒和薄膜装饰的TiO2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评价。很明显，研究人员开始更多地考虑复合纳米级材料和结构作为有吸引力的催化剂。tnt令人兴奋的方面是能够分别修饰内部和外部表面，这可能赋予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完全封装在介孔中或仅包覆在外表面。提出的研究将描述用各种半导体量子点、纳米棒和薄膜装饰TiO2纳米管表面的策略。光降解有机染料的初步结果表明，与基准催化剂相比，其活性有了显著提高。拟议研究的进展也可能导致我们的新技术在光伏等领域的部署。所提出的活性的结果可能有助于确定光催化和水分解的新方向。该项目的广泛影响包括许多任务，这些任务将导致催化和新型纳米材料领域的研究和多层次教育的整合。如果提出的开发用于有机污染物和水转化的TiO2纳米管复合光催化剂的努力取得成功，那么我们预计近期对社会的影响将是显著的。可能从拟议的活动中受益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，一个强大的教育组成部分将与研究活动相吻合。该项目旨在研究纳米科学的当代主题，学生在此项目中获得的技能将增强他们在纳米技术、化学工程和材料化学领域的职业准备。除了关于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，我们还寻求让各级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。我们将参加纳米探索者计划，学生参与讨论，研讨会和实验/研究。我们还致力于其他高中生的研究经验，作为韦尔奇和克拉克基金会暑期项目的一部分，以及针对弱势高中生的ACS项目SEED。预计一名高中教师也会参与这个项目。因此，我们期望这个催化和纳米技术的项目也会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.