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Controlling the Efficiency of Semiconductor-TiO2 for Sunlight-driven Technologies for Military Needs

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Technical Report,01 May 2013,30 Apr 2016

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University of Virginia Charlottesville United States

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How surface chemistry can modify the electronic properties of metal oxide semiconductor nanomaterials relevant to improving sunlight driven military technologies was investigated. Photoluminescence was used to probe the surface band-bending of TiO2 nanoparticles to help identify properties that can control the flow of charge to the semiconductor surface. First, the effects of oxygen exposure on band-bending induced by both healing defects at the surface and molecular chemisorption were studied. Second, probing the band-bending of the TiO2surface under the influence of gases with different electron accepting and donating strengths revealed that band-bending at the surface modulates electron trapping into gold nanoparticles at the surface, when present. Electron donation from the TiO2 surface to gold particles has been shown to be critical in the reactivity of AuTiO2 nanoparticle catalysts and our ability to measure band-bending at the surface aids in understanding how catalysts might be more optimally doped with intrinsically enhanced upward or downward band-bending. Third, the electron mobility changes in TiO2 nanopowder decorated with conductive carbon nanotubes concluded fruitful studies on the effect of surface conductors on charge recombination. Finally, the role that free carriers and neutral donors play in producing visible emission from ZnO nanoparticles was more fully elucidated.

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  • Electrical and Electronic Equipment

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