Pulsed laser based synthesis of polymeric-inorganic nanocomposites as efficient visible light active photo-catalysts for the degradation of organic pollutants in water

Polymeric-inorganic graphitic carbon nitride-cadmium sulfide (g-C₃N₄-CdS) nanocomposites, with different mass ratios of CdS (5 %, 10 %, 20 % and 30 %) anchored in g-C₃N₄ network were synthesized for the first time by laser ablation technique, using a nanosecond pulsed laser of 532 nm wavelength in water medium. The synthesized g-C₃N₄-CdS nanocomposites were used as a catalyst in the process of photo-catalytic degrading toxic cationic and anionic dyes in aqueous solutions under visible light irradiation. Our results revealed that g-C₃N₄-CdS nanocomposites, in general showed better photo-catalytic efficiency than that shown by pure g-C₃N₄, particularly, the nanocomposite with 20 % CdS in g-C₃N₄-CdS yielded the highest efficiency in the photo-catalytic degradation of both the dyes under study. The enhanced photo-catalytic degradation efficiency of g-C₃N₄-CdS nanocomposites, in general is mainly due to the enhanced visible light absorption brought about by the anchoring of CdS on the g-C₃N₄ network, and also due to the reduced photo-generated charge recombination mediated by the formation of heterojunction between the two semiconducting composite partners, which are quite evident respectively from the recorded UV-DRS and PL spectra of g-C₃N₄-CdS nanocomposites. Besides optical characterizations, structural, elemental and morphological characterizations, using XRD, FE-SEM, TEM, HR-TEM, XPS and FT-IR were carried out and the results of this work is elucidated in the light of the characterization studies.