SURFACE-ENHANCED RAMAN SCATTERING AT PHOTOREDUCED SILVER NANOPARTICLES AT SINGLE CRYSTAL TIO2 PARTICLES FOR STUDYING THEIR INTERFACIAL CHARGE TRANSFER ACTIVITIES AND RENEWABLE ENERGY CONVERSION

摘要

With a definite need to find alternate renewable energy sources to fossil fuels, abundant solar energy is one of the priority alternatives and thus efficient conversion systems of solar energy to chemical energy and electricity have been intensely investigated. For example, solar cells have been developed for solar energy conversion directly to electricity and artificial photocatalysts have been used to convert water to hydrogen gas under sun light. One of the greatest setbacks with the solar industry derives from the high cost of current solar cell designs. Another problem facing the photocatalyst studies is the poor visible light conversion efficiency to hydrogen gas so that practical use has not yet achieved to convert solar energy using a photocatalytic system. One of the promising low-cost photocatalysts is titanium dioxide (TiO2) that has been applied to water splitting and dye sensitized solar cells. The organic dye being necessary since TiO2 is a wide band gap material and absorbs only in the UV region. Doped TiO, such as nitrogen doped TiO, has shown visible light response by decreasing the band gap of TiO2 and allowing it to absorb in the visible region. However even with much work being produced visible light response of TiO2 is not efficient enough for practical use and the detailed photoelectrochemical reaction at the nanometer scale at the nanosized TiO2 is not yet fully understood. Thus fundamental work needs to be performed to access the local photoelectrochemical reaction and to study its responses to surface modification.