Absorption properties of boron doped TiO2 was estimated by UV-vis spectroscopy. Figure. 1 shows the absorption spectra of
B-TiO2 doped with boric acid. Since, all samples prepared by hydrolysis in the presence of H2BO3 were inactive in the reaction
of phenol degradation under visible light, they revealed stronger absorption in visible region than pure TiO2. From all samples
the best photoabsorption can be attributed to sample BE-H(10) obtained hydrolysis of TIP in the presence of 10 wt.% of boric
acid.
Figure 2 shows the absorption spectra of B-TiO2 doped with boric acid triethyl ester prepared by grinding of ST-01 with a
dopant. The best photoabsorption in the visible region can be attributed to the sample showing the higher photoactivity in the
reaction of phenol degradation - BE-G(2). We did not observe a red shift for boron-doped photocatalysts but some samples show
lack of sharp absorption edge as observed for pure TiO2.