Preparation Of MoS₂/TiO₂ Composite Catalyst And Its Photocatalytic Activity Under UV Irradiation

Nano-semiconductor photocatalyst has important applications in photocatalytic degradation of organic dyes,photocatalytic hydrogen production.TiO₂ has been extensively studied due to its advantages such as no pollution,wide source,suitable band potential,high photoelectric conversion efficiency,however,when the TiO₂ is excited by ultraviolet light,the electron-hole can be compounded in a very short time,so the catalytic efficiency of TiO₂ is not high.TiO₂ is combined with band-matched narrowband semiconductors to form heterojunction structures,which can make the photogenerated electrons and holes migrate to extend the lifetime of electrons and holes,which is one of the effective methods to enhance the catalytic effect of photocatalysts.In this paper,MoS₂ with different morphology was prepared by one-step hydrothermal method and TiO₂ nanocrystalline particles were grown on MoS₂flower structure to form MoS₂/TiO₂ heterojunction composites.The photocatalytic degradation of rhodamine B and the photocatalytic hydrogen production were tested,the mechanism of photocatalytic hydrogen production was studied and analyzed.TiO₂ mixed crystal linear microspheres were prepared and the photocatalytic degradation of rhodamine B under UV light was carried out;The TiO₂ nanosheets exposed to the {001} crystal face were synthesized and the morphology and phase structure of TiO₂ nanosheets were analyzed.The main results of this paper are as follows:?1?A small area?ultrathin MoS₂ nanosheets were prepared using MoS₂ powder as raw material?n-butyllithium as intercalation agent,HRTEM and Raman characterization demonstrated that the obtained MoS₂ has 1T phase and 2H phase.The prepared MoS₂ is an irregular three-dimensional structure composed of nanosheetsusing molybdenum trioxide and potassium thiocyanate as raw materials,XRD characterization showed good crystallinity.The prepared MoS₂ by hydrothermal method is a flower-like microsphere structure assembled from a two-dimensional nanosheet with a size of about 500 nm.?2?MoS₂/TiO₂ heterojunction composite catalyst was prepared by hydrothermal method using MoS₂ flower microspheres and tetrabutyl titanate as raw materials and HF as reagents.In the absence of precious metal Pt,when the mass percentage of MoS₂ is 30%,the photocatalytic efficiency of photocatalyst is 1004 ?mol·h-1·g-1,which is much higher than other photocatalysts.MoS₂/TiO₂ heterojunction catalyst can significantly improve the photocatalytic hydrogen production efficiency,mainly due to theTiO₂ electrons transfer to MoS₂ edge active sites and defect sites,unsaturated S atoms of these sites can adsorb hydrogen protons to produce hydrogen.?3?TiO₂ nanocrystalline linear microspheres were prepared by hydrothermal method with a size of about 2.5 ?musing P25 as raw material,NaOH?H2O₂?H2O as the Morphology control agent.Under UV irradiation,the degradation rates of rhodamine B for TiO₂ nanocrystalline linear microspheres and P25 were 97%and 91%in 30 min.It is shown that TiO₂ mixed crystal linear microspheres have good photocatalytic degradation ability,mainly due to two reasons,firstly,TiO₂ mixed crystal linear microspheres with large specific surface area can adsorb more rhodamine B on the surface of TiO₂ to participate in the reaction;secondly,the nanowires of TiO₂ mixed crystal microspheres contribute to the diffusion of electrons and holes from the bulk phase to the surface of TiO₂,which reduces the recombination probability of electrons and holes.,reducing the recombination probability of electrons and holes.