The synthesis of nanocrystals is in the limelight in modern nanotechnology. Biosynthesis of nanoparticles by plant extracts is currently under exploitation. Not only could silver nanoparticles ranging from 55 to 80 nm in size be fabricated, but also triangular or spherical shaped gold nanoparticles could be easily modulated by reacting the novel sundried biomass of Cinnamomum camphora leaf with aqueous silver or gold precursors at ambient temperature. The marked difference of shape control between gold and silver nanoparticles was attributed to the comparative advantage of protective biomolecules and reductive biomolecules. The polyol components and the water-soluble heterocyclic components were mainly responsible for the reduction of silver ions or chloroaurate ions and the stabilization of the nanoparticles, respectively. The sundried leaf in this work was very suitable for simple synthesis of nanoparticles.

The electronic structures of Au clusters deposited on the stoichiometric and reduced rutile TiO 2 (110) surfaces were investigated by means of X-ray photoelectron spectroscopy. With the increasing Au thickness, the Au 4f binding energy shifts monotonically toward lower binding energy on the stoichiometric surface, essentially demonstrating a particle size effect. On the reduced surface, the Au 4f binding energy exhibits a monotonically downward shift with the increasing Au thickness below 1.5 Å, then unexpectedly shifts to higher binding energy when the Au thickness increases from 1.5 Å to 2 Å. The Au 4f binding energy shift observed on the reduced surface can be reasonably explained by a collective contribution from the particle size effect and the charge transfer from the reduced surface to Au clusters. Our results experimentally present direct XPS evidence for the charge transfer from the reduced TiO 2 (110) surface to Au clusters.

The development of dependable, environmentally benign processes for the synthesis of nanoscale materials is an important aspect of nanotechnology. In the present study, we report one-pot biogenic fabrication of palladium nanoparticles by a simple procedure using broth of Cinnamomum camphora leaf without extra surfactant, capping agent, and/or template. The mean size of palladium nanoparticles, ranging from 3.2 to 6.0 nm, could be facilely controlled by merely varying the initial concentration of the palladium ions. The polyols components and the heterocyclic components were believed to be responsible for the reduction of palladium ions and the stabilization of palladium nanoparticles, respectively.National Natural Science Foundation of China [20776120, 20576109]; National High Technology Research and Development Program of China [2007AA03Z347]; Natural Science Foundation of Fujian Province of China [2008J0169

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