| Colloidal particles, a kind of old but renewable building blocks, can be applied as"artificial atoms"to fabricate novel functional materials. As for the functional colloidal particles or hybrid colloidal particles, the simple, green, low-cost and scalable synthetic methods are highly required for their applications in various realms. Excellent dispersibility in green solvents especially in water is also highly required. Moreover, excellent dispersibility in both polar and non-polar solvents may widen their use to a considerable extent.In this paper, we focused on the preparation of magnetic and semiconductor colloids via solution-based synthetic methods. First, we paid our attention to one-step and large-scaled synthesis of PAA-modified Fe3O4 nanoparticles sized in ~ 20 nm in a facile aqueous synthetic system with a yield higher than 80%. The as-obtained PAA-modified Fe3O4 nanoparticles can form stable colloidal solution in water and various polar solvents. We also synthesized amphiphilic superparamagnetic ferrite/block copolymer hybrid hollow submicrospheres, and extend their applications in stabilizing the emulsion and controlled manipulation of tiny liquid drops. As a general method, a simple polyol synthetic method has also been applied to prepare amphiphilic nanostructured Ag, Cu, Cd and Ni. A novel chemical"top-down"method has been employed to prepare amphiphilic superparamagnetic Fe3O4 nanobelts with nearly uniform width by using exfoliated millimeter-/micrometer-sized FeOCl as the precursor.Highly monodisperse sub-micrometer CdS colloidal spheres (CSCS) with a controllable and tunable size (between 80 and 500 nm) have been synthesized through a facile solvothermal technique. Owing to the controllability of the reaction process, the growth mechanism of the colloidal spheres has been elucidated in detail. The whole growth process can be summarized as homogenous and slow nucleation of nanocrystals, formation of"cores"via 3D oriented attachment of nanocrystals, and further surface-induced growth to monodisperse colloidal spheres via in situ formation and random attachment of additional nanocrystals. It has been demonstrated that the obtained CSCS colloidal particles are able to be assembled into films which show characteristic stop band gaps of photonic crystals. Using the CSCS as a template, Ag2S, Bi2S3, Cu2S, HgS and Sb2S3 colloidal spheres, which are difficult to obtain directly, have also been prepared successfully through ion exchange.After decomposition of thiourea (TU) in the presence of various metal cations to form metal sulfide nanoclusters, an autocatalytic reaction between TU and the surface of the as-formed metal sulfide dominates the further growth of these metal sulfide nanoclusters. This autocatalytic surface growth is self-correcting, leading to formation of uniform metal sulfide colloidal particles. The size (from nanometer to micrometer) and shape of the particles are able to be tuned simply by varying the reactant concentration, reaction time and temperature. More complex anisotropic particles (including Bi2S3 nanowires, CuS nanorods and CdS anisotropic particles) can also be prepared in the autocatalytic surface growth system.Simply by adding some table salt, we could control the 3D oriented assembly of CdS nanocrystals into crystalline tetra-cone supraparticles (TCSs) in a controlled manner. We show here that Cl– anions and other inorganic anions can act as surfactants to tune both the morphology and properties of the TCSs. The influence of Cl– on the assembly and growth of CdS nanocrystals has been well addressed. The as-obtained TCSs exhibit remarkably enhanced photoelectric and electric properties as compared with the CdS colloidal spheres (CSCS) obtained in the absence of Cl–. This simple approache for the controlled oriented attachment of nanocrystals must be general to other solution-based synthetic system. Moreover, we could get Ag2S 3D superlattices on TCSs with enhanced light absorption in visible area. With suitable molar ratio of Ag and Cd, the Ag2S components could couple well with the CdS TCSs, and therefore result in the excellent absorption of the hybrid collidal particles in the whole visible area and enhanced surface photocurrent. |
