US Egypt Cooperative Research: Mixed Oxide Nanotube Arrays for Solar Energy Conversion: Materials Optimization, Charge Carrier Dynamics and Photothermal Characteristics

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1103827 This project supports a cooperative research project by Dr. Mostafa El-Sayed at Georgia Institute of Technology (Georgia Tech) in Atlanta and Dr. Nahla Abdel-Salam at the National Research Center (NRC) in Cairo, Egypt. Included in the collaboration is Dr. Hasan Talaat of Ain Shams University (ASU), Cairo, Egypt. They plan to study Mixed Oxide Nanotube Arrays for Solar Energy Conversion: Materials Optimization, Charge Carrier Dynamics and Photothermal Characteristics. Intellectural Merit: The construction of high-performance, affordable, and air-stable inorganic photovoltaic and photoelectrochemical devices based on metal oxide nanomaterials which are cheap, abundant and environmentally benign will enable long-term and scalable solar energy conversion. Developments in this area, although encouraging, have failed to achieve wide-scale deployment of new technology to harness renewable energy. Fundamental studies on the electronic properties of dye- and quantum-dot-sensitized solar cells have not kept up with recent advances in nanofabrication of metal oxides. Additionally, efforts to identify loss mechanisms and quantify the amount of heat produced in solar cells, critical to performance and stability, have not been made, particularly in 1D nanoscale materials. This work will extend the synthesis and optimization of uniquely advantageous 1D nano-architectures of various metal oxides and employ them to solar energy conversion devices, considering the production of both current (photovoltaics) and hydrogen (through photocatalysis). Aspects include materials optimization through the use of mixed oxide nano-architechtures as well as new synthetic routes, photocurrent measurements, monitoring the dynamics of charge carriers with ultrafast transient absorption, and quantification of the amount of heat generated during the operation by photothermal spectroscopy. The aim is to look for correlation between the conversion efficiency and the heat evolved or the carrier dynamics and use it to guide modifications to the material composition or method of synthesis for maximum conversion efficiency. The observed correlation may help in understanding the basic mechanism of the conversion process during the operation of such devices. Fundamental and technological challenges will be met by systematically exploring metal oxide doping to lower the electrode bandgap and improve conductivity as well as the use of various sensitizers to improve light absorption. Physical investigations will consider both the energy converted to fuel or electricity as well as the energy lost to heat. This combination of material optimization and fundamental characterization within the same research team is a novel solution to enhance international collaboration. This project will combine the three research groups with experience in their respective areas: nanoparticle and nanotube synthesis and ultrafast dynamics (Georgia Tech.), materials synthesis and characterization (NRC), and photothermal measurements (ASU). Broader Impact: The research can lead to major technological advances in solar energy with major impacts on world societies. As the need for more renewable energy sources is global, the proposed work will be carried out in collaboration with scientists from Egypt, to increase the training, experience, awareness, technology, and resources of both countries as well as the wider world. Key experimental work will be conducted by junior scientists, postdocs, and graduate students in the U.S. and also in Egypt. Postdocs and junior scientists will be responsible for experimental planning, and will gain vital experience in international collaborations. Scientists will travel between countries to exchange knowledge and materials, give lectures, and improve international cooperation. Dr. El-Sayed meets with high-school students through the National Nanotechnology Infrastructure Network youth outreach program and this work will be featured prominently.This proposal is supported under the US-Egypt Joint Fund Program where NSF supports the US side and the Government of Egypt funds the Egyptian side.