Nanocrystalline semiconductor materials for solar water-splitting

The production of hydrogen from water using solar light is very promising for generation of an ecologically pure energy carrier. Semiconductor photocatalysts are used to harvest the light energy and induce the hydrogen and oxygen redox reactions. Different types of TiO2 aerogels have been successfully synthesized and the sample with the highest BET surface area was morphologically characterized with the help of SEM measurements. To improve the photoelectrochemical (PEC) efficiency of the material, it is desirable to red-shift the PEC onset to also include the less energetic but more intense visible part of the solar spectrum. The most efficient and commonly used dyes in dye-sensitized TiO2 solar cells are based on ruthenium complexes. A series of ZnO/TiO2 aerogels were prepared by the sol-gel method followed by supercritical drying. By varying the ZnO quantity (1-10%) and the nature of Zn precursors-zinc(II) nitrate hexahydrate and zinc(II) acetylacetonate, an extensive study has been performed.