Energy Transfer Mechanism Of Nanoparticle Plasmonic Effect In Photocatalytic Hydrogen Production

In this dissertation,the photothermal effect of noble metal nanoparticle plasmons on the photocatalytic reaction was investigated based on Raman spectroscopy.In this dissertation,the specific methods of preparing gold nanoparticles by sodium citrate reduction method,preparing supported Au and Ni nanoparticles by deposition-precipitation method and preparing Ti O₂ and Au-Ti O₂ core-shell nanoparticles by sol-gel method are presented,and the corresponding catalysts have been successfully prepared.Au-Ti O₂ core-shell nanoparticles were successfully prepared on the basis of gold sol.In this dissertation,the experimental study on photocatalytic reduction of water with methanol（CH₃OH）as sacrificial agent was carried out.The results show that the photocatalytic reaction rate of pure Ti O₂ is less than 20μmol?g^-1?h^-1.After loading gold nanoparticles,the photocatalytic reaction rate is increased to about 2700μmol?g^-1?h^-1.After nickel nanoparticles,the photocatalytic reaction rate is increased to about 5700μmol?g^-1?h^-1.After bimetallic loading of Au and Ni,the respective advantages of the two metals are fully utilized,and the photocatalytic reaction rate is improved.to about 6100μmol?g^-1?h^-1.In the Au-Ti O₂ core-shell structure,when the gold content reaches 2%,the photocatalytic reaction rate can also be increased to about 3000μmol?g^-1?h^-1.The photothermal effect and carrier migration of metal plasmons were studied based on Raman spectroscopy.In order to simulate the photothermal effect of the catalyst in the aqueous solution during the photocatalysis process,the Raman spectroscopy of the catalyst film was detected.The Raman spectra were detected by laser excitation at 532 nm and 633nm,respectively.It was found that the temperature increase of Au Ni Ti O₂ was mainly caused by its photothermal effect,and the contribution of carrier migration was more obvious in Ni Ti O₂.The temperature rise of Au Ni Ti O₂ is very obvious,and its carrier contribution is also large,indicating that its photothermal effect is good and its internal carrier mobility is very high.in addition.Comparing the temperature changes of the powder and the film,it can be found that the temperature increase is more significant in the powder state,which is due to the faster thermal conductivity of the catalyst in the film state.The subject uses the software FDTD Solutions to simulate the near-field distribution of nanoparticles,and to study the field enhancement effect of plasmons more intuitively.The establishment of the model is based on the particle structure and size shown by the TEM image,which is as close as possible to the actual particle.The simulation results show that the maximum value of the electric field near Ti O₂ loaded with metal nanoparticles is increased by a factor of about 3.Multiple core-shell particles have an electric field accumulation effect,and the maximum electric field is stronger than that of a single particle.In the nanochain composed of five core-shell particles with a spacing of 2 nm,the maximum electric field strength reaches 15.198 V/m.In this dissertation,the photothermal effect of metal plasmons and the role of carrier migration in photocatalysis are studied in detail,which provides theoretical guidance for subsequent in-depth mechanism research.