Synthesis Of Two-dimensional Materials With Its Photoelectric Properties

In recent years,with the development and application of graphene,various kinds of graphene-like two-dimensional layered materials has triggered a wave of research owing to its unique physical,electronic and chemical properties.Owing to their unique layered crystal structure and high degree of anisotropy,these two-dimensional layered materials have a very large application prospect in various fields.In this paper,the classical graphene two-dimensional layered nanomaterials molybdenum disulfide?MoS₂?and carbon nitride?C₃N₄?were used as the research object.The photocatalytic performance of the material is improved by improving the preparation process.The main work are as follows:?1?The MoS₂ and MoS₂/Graphene nanocomposite with hierarchical structure was synthesized via a hydrothermal approach.The MoS₂ with scrolled nanosheets combined with interconnected graphene network so as to promote the formation of steady hierarchical architecture,and improving conductivity of MoS₂.The effect of the products on the photo-degradation activity was investigated,and revealed that compared with bare MoS₂,the photodegrade ability of MoS₂/graphene composites was greatly improved.Futhermore,we also made a corresponding discussion on the improvement mechanism of photodegradation performance.?2?The WS₂ with hexagonal crystal structure was prepared by using the commercial W powder and S powder as the starting material.The morphology of the product was improved by optimizing the sintering process system.A series of WS₂/MoS₂ composite components were synthesized by hydrothermal method,and the growth mechanism of double petal nanostructures was explored.The photodegradation performance was investigated by degradation of methylene blue?MB?under the irradiation of visible light.The results indicated that the photodegradation rate of both of the pure MoS₂ and WS₂ was low.However,the composite of the two products greatly improved the degradation of organic dyes,and the obtained 4WS₂@96MoS₂ revealed the most excellent photodegradation property.The enhanced photodegradation property was benefit from the formation of the?-type crossed band heterojunction and the increasing of reaction active sites.Moreover,the formation of the heterojunction can improve the photoelectric response performance of composite,which offers theoretical support for the development of optoelectronic devices.?3?The melamine was treated with H₂SO₄,H₃PO₄ and HNO₃,and the supramolecular precursors of different morphologies were obtained by intermolecular hydrogen bonding.Subsequently,the sulfur-doped carbon nitride?S-doped g-C₃N₄?,the phosphorus-doped carbon nitride?P-doped g-C₃N₄?and the undoped carbon nitride?g-C₃N₄?with the graphene-like structure are obtained by further pyrolysis.This method is simple and easy to repeat which could be prepared in large quantities.The surface test shows that the specific surface area of the sample has the relation of S-doped g-C₃N₄>g-C₃N₄>P-doped g-C₃N₄.S-doped g-C₃N₄ samples have a specific surface area of about 180.81 m²/g and a pore volume of 0.9021 mL/g.The photocatalytic properties of the samples were tested by hydrogen production.The results showed that the hydrogen production of S-doped g-C₃N₄was 2.16 mmol,and the hydrogen production rate was 0.473 mmol/h,which was 3.5 times than that of g-C₃N₄.The large specific surface area allows the sample to absorb light energy sufficiently,and also provides sufficient active sites for photocatalytic reaction.