The fabrication of metal nanoparticles has drawn considerable attention because of both fundamental interest and the potential for applications. [1][2][3][4][5] Depending on the exact particle size to be synthesized, elaborate and often time-consuming processes can be required to achieve highly uniform particles. Herein, we demonstrate a simple, inexpensive, and rapid method for making metal nanoparticles ranging between 10 and 100 nm in size. The process can be competed in approximately 11 min without the use of a clean-room environment or vacuum techniques. The method works by using a thin supported TiO 2 film as a photocatalyst and an alumina membrane as a template. The nanoparticle array formed in this manner is nearly monodisperse and the particle surface density and geometry are uniform over large areas. The templates are reusable and the technique may be amenable for biosensing as well as catalytic applications.
Metal nanoparticles possess unique physical, magnetic, optical, electrical, and catalytic properties. [1][2][3][4][5] Gaining control over their size and geometry during the fabrication process is of central interest. This has led to remarkable achievements in the preparation of nearly monodisperse particles up to approximately 10 nm in diameter by employing synthetic methods. [6][7][8][9][10] Moreover, photolithographic methods now make it possible to precisely control geometries down to the 100 nm scale. [11][12][13][14] There are, however, fewer methods for easily fabricating highly uniform metal nanoparticle arrays on an intermediate length scale.
Previous fabrication efforts on the 10 to 100 nm scale have included reduction synthesis and nanolithography. [15][16][17][18] Also, template approaches have been used to synthesize nanotubes, [19][20][21][22][23][24][25][26][27][28] nanorods, [29,30] nanoelectrodes, [31] and nanoparticles. [32,33] Some of these techniques depend on wet electrochemical methods to deposit metal onto a uniform nanoporous template, [20][21][22][23][24][25][26][27][28][29] while others apply thermal or electron-beam evaporation followed by etching procedures. [32,33] Anodic aluminum oxide (AAO) templating has been widely exploited in these applications because of its uniformity, rigidity, and size-controllable properties.