Synthesis, Characterization and Application of Semiconductor Nanocomposite Materials for Water Pollutant Removal

Different morphologies and crystal phases of black TiO2 including hydrogenated anatase TiO2 nanoparticles with the core shell structures and yolk shell TiO2 microspheres, vertically aligned MoS2 and MoSe2 Nanosheets (NSs), MoO3 Quantum Dots, and Inorganic Fullerene-Like structures of MoSe2 NSs were synthesized by Pulsed Laser Ablation in Liquid (PLAL) followed by microwave technique. The Yolk–Shell Like TiO2 microspheres (YSHL-TiO2) showed rutile phases in the shell which encapsulate Lattice Expanded Planes in the core and size-dependent lattice expansion from 0.35 nm to 0.94 nm. Moreover, formation of MoSe2 nanoparticles with expanded interlayer spacing along the (002) planes and selective oxygen incorporation along the (100) and (002) planes were shown. Based on PLAL synthesized nanostructures, TiO2-ZSM5-MoS2 and a 3D porous BlackTiO2(BTiO2)/ Inorganic Rutile Hollow Microspheres (IRHM)-MoS2 nanocomposites were synthesized. The FTIR and spectroscopy analysis confirmed phase transitions and formation of different crystal disorders such as amorphous layers, oxygen vacancies and three valence states of titanium in crystal structures of Black TiO2 (BTiO2) and MoS2 NSs. The photocatalytic capabilities of the materials were tested with arsenite and Methylene Blue (MB). Black TiO2 and yolk–shell TiO2 microspheres showed approximately 71% and 99% of arsenite photooxidation and MB photodegradation under visible light irradiation. BlackTiO2/IRHM-MoS2 composite demonstrated the maximum photocatalytic degradation of approximately 100% for Methylene Blue and 98% arsenite photooxidation under visible light irradiation. TiO2-ZSM5-MoS2 composite exhibited approximately 100% arsenite photooxidation under UV irradiation. Enhanced visible light absorption induced by surface and morphology modification and increased charge carrier lifetime due to the formation of the different types of heterojunctions which were anatase/rutile, anatase/MoS2, rutile/ MoS2 and anatase/ZSM-5 may explain the higher photocatalytic performance of synthesized nanostructures. Moreover, Photoluminescence analysis indicated that OH − radicals were the main active species involved in the photocatalytic degradation and oxidation tests and therefore the photocatalysis mechanism was accordingly suggested.