| The size and morphology of noble metal nanoparticles generate the significant influences on their optical,electrical,and catalytic properties.As the most commonly used method for preparing nanoparticles,the chemical reduction approach allows to fabricate different kinds of nanoparticles with high stability,uniform size,and various morphologies.In this procedure,the surfacetant and reducing agent play the critical role in tuning the size and morphology of particles.Therefore,the development and optimization of surfacetant and reducing agent are beneficial to tuning the morphologies of Au micro/nanostructures efficiently.It is of great significance to explore the growth process and mechanism to improve its performance and extend its practical applications.In this dissertation,a novel "one pot" approach is developed successfully to prepare the gold micro/nanoparticles based on the simple inorganic agent of SbCl3.Based on the sole role of SbCl3 or combination with other surfactants,it effectively tunes the size at micro/nano scales and the rich microstructures of gold micro/nanoparticles.The optical enhancement and photocatalytic performance are investigated accordingly.It provides a novel approach and new strategy for the synthesis of gold micro/nanoparticles.The main results are listed as follows:1.Developing a novel approach for preparing the gold microplate in "one pot"based on the inorganic reducing agent of SbC13.The upper and lower surfaces of as-prepared gold microplates are atomic flat single crystal surfaces of {111}.During the reaction procedures,the reducing agent of SbCl3 is oxidized to Sb(V)and chlorauric acid is reduced to Au(0).The adsorption of Cl-on Au {111} facilitates the growth of the microplate.With the coexistence of CTAB,the Au concave plates are grown due to the selective adsorption of CTAB on the {100} facet which blocked the further growth of lateral faces.The thickness of both Au microplates varying from several tens to hundred nanometers are controlled by the reaction duration.2.By using KI as an additive agent,flower-like gold microparticles are fabricated with rich microstructures.The morphologies of particles are examined by SEM in the different reaction periods,and the growth mechanism is proposed accordingly.The results demonstrate that the regular octahedron with eight {111}facets is produced in the initial stage.Its further growth is blocked due to the stronger adsorption of I-ions on these new {111} facets.However,the faces in the center of the particles grow continuously to form the stacking fault and twin defects,which induced the changes in the growth direction of gold plate.Finally,it results in the formation of the flower-like gold microstructures.After combined with the gold nanoparticles monolayer film,the SERS activities of flower-like gold microstructures are improved mainly due to the additional coupling effect of multi-microstrcuures3.The morphologies are tuned at the nanometer scale by the introduction of PVP.The gold nanostars are obtained successfully with the maximum size of about 25 nm at radial direction.The orthogonal experiments are employed for investigating the roles of PVP and SbCl3,and the growth mechanism is proposed accordingly.The results indicated that spherical gold nanoparticles with size of about 10 nm and twin structure are formed by the reduction of PVP.By combining the interaction of PVP and SbCl3,the growth of {111} and {110} facets of gold seeds is inhibited dramatically,while the {100} facet grows continuously and results in the formation of gold nanostars.The performance of SPR catalytic PNTP coupling and electrochemical catalysis H2O2 reduction is investigated.Combined with the FEM simulation,the tip-tip coupling mode exhibits the stronger SERS effect and achieves the maximum of SPR catalytic efficiency.Comparing to the normal gold nanoparticles with diameter of 30 nm,the electrochemical catalytic activity on the reduction of H2O2 is improved by about 1.8 times. |
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