Modified titanium dioxide photocatalysts for the enhanced photodegradationof organic substrates

Two approaches to generate TiO2 photocatalyst for the enhanced photodegrada tion of substrates are described. One approach includes the surface modific ation of TiO2, with a layer consisting of a N,N'-bipyridinium pi-acceptor l ayer. The resulting photocatalyst reveals superior photocatalytic activity as compared to the non-modified TiO2 for the decomposition of pi-donor subs trates such as 1,4-dimethoxybenzene (1), 1,2-dimethoxybenzene (2) and indol e(3). The enhanced photocatalytic activity of the modified TiO2, V2+-TiO2 i s attributed to the concentration of the pollutant at the heterogeneous cat alyst surface via the formation of supramolecular pi donor-acceptor complex es. A second approach to improve the photocatalytic activity of TiO2, involves its doping with Fe(III)-Phthalocyanine, Fe(III)-Pc. The Fe(III)-Pc doped Ti O2, Fe(III)-Pc/TiO2 is formed by the sol-gel method. The series of organic substrates p-nitrobenzoic acid (5), p-aminobenzoic acid (6), p-chlorophenox yacetic acid (7), salicylic acid (8) and aniline (9), is effectively degrad ed by the Fe(III)Pc/TiO2 catalyst compared to the non-modified catalyst. Ph otodegradation of the organic pollutants in the presence of Fe(III)-Pc/TiO2 , is substantially enhanced as compared to non-modified TiO2, and leads to complete mineralization. The enhanced activity of the Fe(III)-Pc doped TiO2 , is attributed to the synergistic generation of (OH)-O-. radical, the acti ve species in the degradation of the organic substrates, at the semiconduct or surface, via the photochemical cleavage of light-induced generated H2O2 at the semiconductor surface.