Inorganic nanoparticles: Synthetic shape control and catalytic studies

Nanomaterials are receiving more and more attention due to their special properties compared to the bulk. It is also known that many of these properties are size and shape dependent. Hence, much research has been devoted to the shape and size control of nanostructures. We report here the solution-phase synthesis of inorganic nanoparticles with controlled shapes, such as highly uniform and monodisperse cubic Cu2O nano and microcubes, La/Cu/O and gold nanorods.; For Cu2O microcubes, Copper (II) salts in water are reduced with sodium ascorbate in air, in the presence of a surfactant. The average edge length of the cubes varies from 200 to 450 nm, as a function of surfactant concentration. Transmission electronic microscopy suggests that these cubes are composed of small nanoparticles and appear to be hollow. Highly uniform Cu2O nanocubes can be prepared by reducing copper(II) salts in water with ascorbic acid in air in the presence of polyethylene glycol (PEG) and sodium hydroxide. The average edge length of the cubes can be controlled from 25 to 200 nm by changing the order of addition of reagents, and the PEG concentration.; In addition to the synthesis, nanoindentation tests were performed directly on solid and hollow cuprous oxide (Cu2O) nanocubes. The hardness and elastic modulus of solid Cu2O nanocubes were measured and compared with the values of bulk Cu2O. It is found that the hollow cube top wall acts as a membrane that bends under an indentation load. The Cu 2O nanocubes are more ductile rather than brittle. Deformation behavior and fracture mechanics are discussed in conjunction with the structure of the Cu2O nanocube.; To explore the potential catalytic applications of inorganic nanomaterials, we prepared some rod-like La/Cu/O nanoparticles by a simple hydrothermal reaction with a sonication process. Catalytic study shows that these nanoparticles are highly active as catalyst for the hydroxylation of phenol. Compared to the 4--6 h, 40% of phenol hydroxylation yield reported in literatures, our nanoparticle catalyst demonstrates a nearly 100% conversion within 3 h based on GC.; In addition, the shape changing properties of gold nanorods were explored by performing different treatments to unpurified gold nanorod solutions, which was synthesized by a seed mediated growth approach.