Replacing polluting fossil fuels with clean alternatives is one of the grand challenges of the modern world. A more sustainable energy economy may be achievable with photocatalysts that can produce hydrogen fuel from water, using sunlight as the only energy input. Hydrogen is regarded as a "green" fuel because it releases its stored energy by re-forming water. A problem of known photocatalysts is that their energy conversion efficiency is low, that is, they absorb a lot of energy from sunlight but only some of this energy is converted to a usable fuel. This project studies the use of "ferroelectric" light absorbers to increase the energy conversion efficiency. The new ferroelectric light absorbing materials are studied using microscopic, optical, electrical, and chemical methods. The research is conducted by a postdoctoral associate and by graduate students. All team members are trained in the preparation of the materials and in the application of modern instruments and techniques for their characterization. New internship positions for undergraduate students from underrepresented groups are also created. Chemistry shows at local schools and on campus motivate children to study the natural sciences, tackling important societal problems like clean energy. Experimental demonstrations are distributed as online materials to educate the public about sustainable fuel research.
With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Osterloh of the University of California, Davis, is studying ferroelectric effects in a set of photocatalyst materials derived from the perovskites M:ATiO3. Here, A is an earth alkaline element and M is a transition metal ion. These materials are relevant to the development of third generation photovoltaic devices and photocatalysts for the production of sustainable energy. The compounds are synthesized with solid state and hydrothermal methods from abundant elements, and they are characterized with electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV/vis spectroscopy. Site-selective modification with water oxidation and reduction co-catalysts is applied to fabricate ferroelectric photocatalysts for the overall water splitting reaction. A combination of dielectric polarization experiments, surface photovoltage spectroscopy, photocatalytic, and electrochemical measurements is used to determine the extent to which ferroelectric dipoles can enhance photochemical energy to fuel conversion with these materials. Additionally, the project trains graduate, postgraduate and undergraduate students in the preparation of inorganic materials and advanced methods for characterizing their morphology, structure and photochemistry. Outreach events are conducted to engage and motivate the next generation of STEM students for research in catalysis. Online materials are disseminated to educate the public about sustainable energy production.
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.
