Liquid-Phase Synthesis, Structural Characterization And Properties Of Some Metal And Alloy Nanomaterials

Metal nanomaterials have broad prospects in the field of catalysis, nonlinear optics, magnetic, etc. Thus, more and more efforts have been devoted to the study of them. In this dissertation, solution-based chemical methods have been developed to synthesize the metallic and alloy nanoparticles, i.e., Au, Pt/Cu, and Pd/Ag nanomaterials have been synthesized employing the microemulsions and solvothermal methods, respectively. Moreover, the structures and properties of the prepared metal and alloy nanomaterials have been investigated systematically. Base on the prepared gold nanoparticles, the gold model catalyst has been synthesized and employed to investigate the relationship between particle size and CO catalytic oxidation activity. Furthermore, the alloy nanoparticles of Pt/Cu and Pd/Ag have been prepared and characterized thoroughly. Additionally, the mechanisms and the factors influencing the formation of the alloy nanoparticles have also been explored, respectively. The main results are summarized as follows. 1. The relationship between particle size and CO catalytic oxidation activity of gold nanoparticle catalysts has been investigated systematically. It is difficult to investigate the relationship between particle size and CO catalytic oxidation activity of gold catalysts because of the effect of the preparative methods and supports employed. To give more reasonable results, the gold model catalysts supported on γ-Al₂O-3 have been prepared via the gold sol with different particle sizes by micelle method. Two groups of gold catalysts with different sizes have been prepared by varying the ratios of PVP/Au and the calcination temperatures of the catalysts, where the catalysts were characterized by HRTEM and XRD, respectively. Furthermore, the catalytic activities were tested by CO oxidation. Experimental results show that the catalytic activity becomes much weaker with the increasing of the particle size from 3 to 7 nm, suggesting that the particle size is a key factor to govern the catalytic activity. Obviously, as for the investigations of the relations between the size and activity, the method adopted here has two main advantages compared with others...