(536e) Electrochemical Synthesis of Organic Nanorods on Gold Nanoparticles Seeds

This talk is focused on nanoparticle-directed synthesis of tetrathiafulvalene charge-transfer salt (TTFBr) and potassium tetracyanoplatinate (KCP) organic nanorods using electrochemical deposition. Gold nanoparticles (AuNPs) acting here as nucleation seeds are deposited on highly oriented pyrolytic graphite (HOPG). The nanorods, either TTFBr or KCP, are deposited subsequently on the AuNPs-decorated HOPG for the study of seed-mediated crystallization process at the nanoscale. Both the seed and the organic crystal are deposited using electrochemical chemistry. The deposition processes are monitored by cyclic voltammetry and in-situ atomic force microscope. The field emission scanning electron microscope is also employed to characterize the seed and crystal nanostructures. The TTFBr and KCP crystals deposited on AuNPs-decorated HOPG show preferential nucleation on the AuNP in comparison with crystals electrochemically deposited on the planar HOPG. The size of the crystals is controlled predominantly by the solution concentration and the seed size. Nanorods as small as 7 nm in height are nucleated on AuNPs of 20 nm in height. We hypothesize that the local curvature of the seed particle, that limits the cross sectional dimension and introduces an interfacial strain, contributes to the nanoconfinement effect observed. Currently we are also applying this seed-directed synthesis method to fabricate organic nanowire sensors on gold lithographical patterns. The prototype sensor shows potential to compete with commercial sensors in detecting toxic and flammable gases. This research contributes a better understanding of crystallization at the nanoscale and a possible low-cost technology for chemical sensing applications.