Construction And Photocatalytic Properties Of Noble Metal-sulfide Semiconductor Hybrid Nanostructure

The noble metal-semiconductor hybrid nanostructure is a kind of multicomponent superstructures with configurable nanoscale coupling,which has important application prospects in photocatalysis,electrocatalysis and solar cells.The composite of noble metal and semiconductor nanomaterials can not only promote the separation of photogenerated carriers,but also accelerate the generation rate of photogenerated carriers under the effects of surface plasma resonance?SPR?and exciton absorption.In this paper,different configurations of gold?Au?-cadmium sulfide?CdS?hybrid nanostructures and noble metal-multi-sulfide semiconductor hybrid nanostructures are builded by using ligands,ion exchange,self-assembly and nanoscale solid phase reaction,and their formation process and growth mechanism are discussed.The relationship between the microscopic structure and photocatalytic performance for noble metal-sulfide semiconductor hybrid nanostructure is also investigated.The Au nanoparticle is a common metal nanoparticle with unique SPR effect and strong chemical inertia,and usually used for controllable synthesis of Au-single component sulfide semiconductor hybrid nanostructure.By solution reduction method,Au nanoparticles are uniformly loaded on the CdS nanochains?CSC?derived from cadmium hydroxide nanofiber to form Au-CdS hybrid nanochains?CSC-A?.Au nanoparticles of different sizes can be generated by controlling the composition of reducing agent.Analysis results show that the absorption of visible light and intensity of electric field depend on the size of Au nanoparticles,and the SPR effect becomes stronger with the increasing of the size of Au nanoparticles.The photoelectric performance of Au?5 nm?-CdS nanochains?CSC-A5?is investigated as well.The results show that the photocurrent response intensity of CSC-A5 is 0.462 ?A cm^-2which is 3.27 times the intensity of CSC,then the seperation rate of photogenerated electrons and holes is improved effectively.By further regulating the dipole-dipole interaction between Au nanoparticles,the noble metal-sulfide semiconductor hybrid nanostructures with stronger SPR effect is design and synthesized.Au nanoparticles are assembled into chains with different sulfur sources,and then combined with CdS to prepare the Au@CdS chain-shaped core-shell hybrid nanostructure?ACNC?.The FDTD simulation results show that the ACNC exhbits stronger visible light absorption ability and electric field intensity.By adjusting morphology and optical properties,the photocatalytic activity of the ACNC is significantly improved.Its photocatalytic degradation and hydrogen production rates for the methylene blue?MB?are respectively 0.043 min^-1 and 881.55 ?mol g^-1 h^-1,which are 3.07 times and 3.8 times rates of the Au@CdS core-shell nanoparticles?AC?respectively.Compared with Au nanoparticles,the silver?Ag?exhibits more active chemical properties,which offers more favorable conditions for the construction of noble metal-multi-sulfide semiconductor hybrid nanostructures with multicomponent,diverse morphology,stable structure,and powerful function.By simple vulcanization reactions,the Ag nanoparticles modified with different ligands are used as the basic elements to synthesize Ag-Cd_xAg_2-xS hybrid nanostructures with diversified morphologies and components.Using a combined method of multiscale simulation and theoretical study,the mechanism that the formation of the Ag-Cd_xAg_2-xS with different configurations is influenced by chemical reaction kinetics and phase separation effect is revealed.The results also show how the molecular information encoded on particle surface can be transferred into distinct composite patterns.The Au-Ag-Cd_xAg_2-xS hybrid nanostructures with built-in hot spots can be further synthesized using Au@Ag core-shell nanoparticles with mixed surface layers.The photocatalytic degradation efficiency for the MB can reach at least 92% in 40 minutes,which is 60 minutes faster than that for the Ag-Cd_xAg_2-xS.Bimetallic Au@Ag core-shell nanoparticles are more favorable for the synthesis and control of the noble metal@multi-sulfide semiconductor hybrid nanostructures.By regulating the reaction time and using the self-assembly and chemical transformation coordination method,Au@Ag core-shell nanoparticles are used as the basis to obtain Au@Ag₂S chain-shaped core-shell hybrid nanostructure?AA?and Au@Ag₃AuS₂ eccentric core-shell hybrid nanostructure?ECSC?with truncated octahedral configuration.The transformation process from the AA to the ECSC is proved by the mechanism of in-situ sulfidation and solid-state reaction.Through the ion exchange reaction between different cations and AA,the noble metal@multi-sulfide semiconductor hybrid nanostructures are obtained.Research results show that the Au@Ag₂S-CdS hybrid nanostructures?AAC?has highter photocatalytic activity contributed by the multi-component of sulfide,and the photocatalytic degradation efficiency for the MB can reach at least 95.6% in 50 minutes,which are respectively the 1.8 times and 1.29 times efficency of the AA and ECSC.