An Efficient and Robust Method for Selective Conversion of Aniline to Azobenzene Using nano-TiO -P25-SO H, under Visible Light Irradiation.

Nano-TiO -P25-SO H as our previous report has successfully been utilized to synthesize azobenzene through the selective conversion of aniline under visible light irradiation. According to PL emission spectra, the immobilizing a solid Brønsted acid of -SO H groups on the pure-TiO -P25 surface with a close interface is an approach to amplify the nano-TiO -P25 response to visible light, which can productively hinder the recombination rate of photogenerated electrons and holes as carriers. Therefore, the photocatalytic activity of the semiconductor is highly likely to increase. Photooxidation of aniline to azobenzene was achieved by applying nano-TiO -P25-SO H (E  = 2.6 eV) that activated by blue photons (λ  = 460 nm), green photons (λ  = 510 nm) and red photons (λ  = 630 nm) which is introducing as a sustainable procedure. Central composite design (CCD) was employed for evaluating the effects of photocatalyst amount, oxidant concentration and irradiation time on the synthesis of azobenzene by this approach. Easily synthesizing, recyclability of the photocatalyst, mild reaction condition and short reaction time could be considered as plus points of this process.