Assembly of hydrothermally synthesized tin oxide nanocrystals

We have successfully assembled highly crystalline tin oxide nanoparticles, which were synthesized through a simple hydrothermal approach, onto the chemical template of octadecyltrimethoxysilane self-assembled monolayer (OTS-SAM). Tin oxide nanoparticles were synthesized by refluxing ethanol containing 0.1 M of tin (IV) chloride pentahydrate at 70 °C for 3 h, and subsequently hydrothermally treating the resulted precipitates at 200 °C for 80 h. As a result, we could obtain the highly crystalline tin oxide nanoparticles. The average particle size and its distribution were estimated by high-resolution transmission electron microscopy observation to be about 5.8 nm and 27.6%. Area-selective assembly of tin oxide nanoparticles was performed by dipping a few drops of the suspension containing the nanoparticles onto the OTS-SAM template-covered silicon substrates, and then sonicating the substrate covered with the dried suspension in absolute toluene for 10 min. The nanoparticles assembled on the methyl-covered regions of the template were easily eliminated from the surface by the sonication, while those on the silanol-covered regions of the template remained tightly adhered to the substrate surface. As confirmed by atomic force microscopy, one-dimensional microarray of tin oxide was achieved on the substrates.