Graduate School of Sciences and Technology for Innovation, Faculty of Engineering, Yamaguchi University, 2-16-1 Tokiwadai Ube, 755-8611 Japan
A commercial titanium dioxide powder (TiO2, P25, Evonik) was immobilized on porous mullite tubes by simple mechanical scrubbing followed by heat treatment at 673 K in air and by dip-coating followed by curing at 393K in air. A dispersant of P25 powder in isopropyl alcohol with a small amount of titanium isopropoxide (TIPP) was used for dip-coating. The surface morphology of TiO2 membranes was different depending on the preparation method: mechanical scrubbing resulted in a smoother surface and dip-coating resulted in a rougher surface consisting of particles smaller than 0.1 μm, which size is almost the same as P25. TiO2 and Ag-TiO2 membranes were tested with formic acid decomposition in water. The difference in morphology influenced the photochemical deposition of silver on the TiO2 membranes. Silver deposition improved the formic acid decomposition rate of TiO2 membranes prepared by mechanical scrubbing. This decomposition rate decreased when silver was deposited on TiO2 membranes prepared by dip-coating.