Surface-area-controlled porous TiO thin films were prepared via a simple sol-gel chemical route, and their gas-sensing properties were thoroughly investigated in the presence of typical oxidizing NO gas. The surface area of TiO thin films was controlled by developing porous TiO networked by means of controlling the TiO-to-TTIP (titanium isopropoxide, CHOTi) molar ratio, where TiO nanoparticles of size ∼20 nm were used. The sensor's response was found to depend on the surface area of the TiO thin films. The porous TiO thin-film sensor with greater surface area was more sensitive than those of TiO thin films with lesser surface area. The improved sensing ability was ascribed to the porous network formed within the thin films by TiO sol. Our results show that surface area is a key parameter for obtaining superior gas-sensing performance; this provides important guidelines for preparing and using porous thin films for gas-sensing applications.

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SiO 2 nanoparticle (SNP, 5-30 nm) together with titanium isopropoxide (TIPP) is tested as a new type of mixed inorganic binder for a low-temperature cured TiO 2 photoanode, of which the photoconversion efficiency is compared with that of the single binder TIPP. The microstructure of the photoanode using the mixed binder shows enhanced consolidation and, thereby, reduced electrical resistance. Resultantly, the photoconversion efficiency is enhanced by around 10 % by the mixed binder. The EIS analysis shows an increase of electron lifetime at the interface of TiO 2 /dye/electrolyte, which supports the efficiency enhancement by the mixed binder. However, the mixed binder is not always playing the favorable role for the efficiency so that it increases charge transfer resistance at the interface between photoanode and transparent-conductive-oxide film due to the insulating SiO 2 nanoparticles sacrificing part of the enhanced efficiency.