The photocatalysts produced so far with P25 were still very unstable despite calcination with the laser. For this reason, another coating technique based on titanium tetraisopropoxide (TTIP) was investigated in addition to using P25 particles for the production of the photocatalyst layer. The catalyst was coated 1 to 5 times with the TTIP solution on the SiO2-sputtered plates and annealed at different laser intensities (8%, 9%, 10%) after each coating step. It can be clearly seen in Figure that there are no Raman signals attributable to crystalline anatase or rutile anywhere on the sample before laser annealing.