Synthesis And Photocatalytic Properties Of G-C₃N₄/TiO₂ Composites

In this thesis,microspheres and microflowers TiO₂ have been prepared via a simple and green hydrothermal technique by using inorganic titanium precursors.And g-C₃N₄/TiO₂ composites have been prepared via a impregnation-pyrolysis method.In addition,g-C₃N₄ were grown on the surface of TiO₂ in situ by a one-step hydrothermal method.The crystal,morphologies and specific surface area of the obtained samples were characterized by using XRD,SEM and BET respectively.The FT-IR was used to research the molecular structure of the samples.The optical property of the obtained samples was characterized by DRS and PL.The properties of as-prepared samples have been investigated,such as photocatalytic decomposition of water into hydrogen,photocatalytic decomposition of organic dyes.The main research content is as follows:?1?The sea urchin-like TiO₂ microspheres were synthesized were synthesized via a one-step hydrothermal method by using K₂TiO?C₂O₄?₂ as the Ti source.TiO₂/g-C₃N₄composites have been prepared via a impregnation-pyrolysis method.The experiment of·OH trapping was performed to reveal the possible charge separation and transfer mechanism.The possible mechanism of high photocatalytic activities was also discussed.The improved photocatalytic activities can be attributed to the fast migration rate of the photo-induced charge carriers and the strong redox capacities,which benefit from the Z mechanism of charge transfer between g-C₃N₄ and TiO₂.?2?The flower-like TiO₂/g-C₃N₄ microspheres were synthesized were synthesized via hydrothermal and impregnation-pyrolysis methods by using Ti?SO₄?₂ as the Ti source and urea as the CN source.TiO₂/g-C₃N₄ composites have been prepared via a impregnation-pyrolysis method.The as-prepared composites were evaluated by photocatalytic hydrogen evolution and photocatalytic decomposition of MB.The results indicate that the g-C₃N₄/TiO₂ composites by adding 25%g-C₃N₄ have the highest photocatalytic activities.Free radical and·OH trapping experiments were performed to reveal the active species and possible charge separation and transfer mechanism.The possible mechanism of high photocatalytic activities was also discussed.?3?The g-C₃N₄ were synthesized by synergistic protonation and intercalation reactions firstly.And then g-C₃N₄/TiO₂ composites have been prepared via a one-step hydrothermal method.The obtained sample were characterized by XRD,SEM,PL,and DRS.The results show that the g-C₃N₄ are uniformly loaded onto the surface of TiO₂,and the separation efficiency of photogenerated electrons and holes is increased.The as-prepared composites have been evaluated by photoelectrochemical and photocatalytic properties.The results show that different g-C₃N₄ dosages have great influence on the photocatalytic activity of as-prepared samples.The sample with using 10 mg g-C₃N₄preparation has highest photocatalytic activities.