Photochemistry in nanotechnology and catalysis

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The paradigms of photochemistry and physical organic chemistry guide our strategies for the synthesis, modification and utilization of nanostructured materials incorporating semiconductor, plasmonic and acid-base structures for catalysis and health applications. New materials are designed for specific applications in catalysis, water splitting/treatment and health. The synthesis of complex nanostructures, especially using photochemistry, combine semiconductors such as TiO2 and Nb2O5 with metals or their oxides (Au, Ag, Cu, Pt, Pd, Ru, Co, Ni, where heat or different excitation wavelengths control the reaction outcome, while Cu-on-TiO2 that can drive click chemistry on demand under visible light. Different metals and their combinations open new opportunities to address organic chemistry challenges. We look intimately at chemical transformations, avoiding the black-box' approach to catalysis. Among these, from the molecule to the mole takes advantage of knowledge acquired using single molecule spectroscopy (SMS) and laser flash photolysis (LFP) to inspire bench scale improvements. We plan to examine organic reactions that can benefit from these approaches. We can manufacture and evaluate new catalyst performance, and use SMS and imaging methodologies to inspire bench scale advances. An area of interest is water splitting/decontamination that have been frequently treated as orthogonal fields, using sunlight to either produce H2 or decontaminate water, yet, they are intimately related. Research on water splitting has utilized solar light, semiconductor catalysis and frequently “sacrificial electron donors”, molecules that facilitate H2 evolution at the expense of the degradation of valuable chemicals. In a novel approach, we propose that water contaminants can act as sacrificial donors, enhancing H2 production while simultaneously decontaminating water (chemically & bacteriologically). Initial tests show that waters from local rivers produce more H2 than pure water, as minor contaminants act as sacrificial donors. In the development of photocatalysts, we view water splitting and purification as two facets of the same problem. We propose H2 production and water decontamination as coupled processes. In health and cosmetics our studies focus on antibacterial properties of nanomaterials and the effect of organic shells on cosmetic materials, such as lignin-coated TiO2, a major sunscreen ingredient with a reputation for adverse health effects that lignin can prevent.