Atomic-layer Ultrathin Chalcogenide Semiconductor Nanosheets Preparation And Its Application In Photocatalytic Water Splitting And Gas Sensing

Ultrathin 2D nanomaterials are widely used in catalysis,optoelectronic devices and other fields due to the advantages of ultrathin thickness,large specific surface area and clear atomic structure.Different from the common layered ultrathin 2D nanomaterials,the synthesis of non-layered ultrathin 2D nanomaterial is more challenging.In this paper,a series of 2D CdS nanosheets were prepared by chemical vapor deposition.Due to advantages of 2D nanomaterials,the performances of 2D nanomaterials were significantly improved in the field of gas detection,photocatalytic decomposition and electrocatalytic reduction.1.Cd@CdS nanosheets were successfully obtained under the proper concentration of SO₂ active gas.Combined with chemical vapor deposition method and dilute acid etching method,atomic-layer ultrathin CdS nanosheet structure was successfully synthesized.Based on the fine characterization of its structure,it is proved that it is Cd₄S₅ nanosheet with non-stoichiometric ratio,and both ends of the nanosheets are exposed to the S-end surface.The same method can be used to synthesize atomic ultrathin ZnS nanosheets.The above synthesis method provides a new idea and direction for the design and synthesis of new two-dimensional ultrathin materials.2.The S-riched atomic ultrathin Cd₄S₅ nanosheets show superior photocatalytic activities and stability.The photocatalytic hydrogen production rate of 1 nm Cd₄S₅nanosheets was 34.8 mmol/h/g under visible light irradiation.And the photocatalytic activity doesn’t decrease after 50 h irradiation.The photocatalytic performance achieves the highest performance of the pure CdS material system.At the same time,CdSe,CdSe_0.8Te_0.2,ZnO,ZnS and other nanosheets were synthesized by using Cd/Zn nanosheet as the template,and profermances of photocatalytic and photoelectrocatalysis was significantly improved.3.The prepared CdS nanoflakes grown directly on the interdigitated electrode are enclosed with high-energy（0001）facets.Their thickness is reduced below the double Debye length of CdS,permitting to achieve a full depletion of carriers.The sensitivity of ultrathin CdS nanoflakes is 12 times that of CdS nanoparticles when exposed to isopropanol.Moreover,the CdS nanoflakes demonstrate excellent gas sensing and light-response properties,thus being capable of dual gas and light detection.