Three way electron transfer of a C-N-S tri doped two-phase junction of TiO2 nanoparticles for efficient visible light photocatalytic dye degradation

C-N-S tridoped TiO2 nanoparticles were synthesized by a sol-gel method using thiourea as a compound source of carbon (C), nitrogen (N) and sulphur (S). 15 wt% of thiourea has been used for effective dopants with different annealing temperatures (300, 400, 500 and 600 degrees C). X-ray diffraction results show that tridoping with C-N-S could effectively restrain the phase transformation of anatase to rutile at a higher annealing temperature (600 degrees C). The size-strain plot method indicates that the crystallite size decreases from 32 to 9 nm with the addition of dopants. Fourier transform infrared analysis shows that the peaks observed at 1384, 1128 and 1051 cm(-1) are attributed to the N-H bond, bidentate S-O coordination to Ti4+ and the Ti-O-C bond. A UV-Vis study reveals that C-N-S tridoped TiO2 is redshifted compared to pure TiO2. From the photoluminescence spectra the band edge emission is redshifted with different excitation wavelengths (280-320 nm). Enhancement of Rhodamine B dye degradation is observed for C-N-S tridoped TiO2 nanoparticles (99% at 180 minutes) compared with undoped TiO2 under visible light irradiation.