TiO2 Nanotube-Quantum Dot Composites for Photocatalysis

University Of Texas At Dallas, Richardson TX

Investigators

Abstract

0854059 Balkus, 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.