(409a) Electrochemical Synthesis of Organic Nanorods on Gold Nanoparticle Seeds

This talk describes seed-mediated nucleation and growth of organic nanorods of tetrathiafulvalene charge-transfer salt (TTFBr) and potassium tetracyanoplatinate (KCP) using electrochemically deposited gold nanoparticles (AuNPs) as nucleation seeds. Both the AuNP seeds and the organic crystals were electrochemically deposited on the highly oriented pyrolytic graphite (HOPG) substrate. The electrochemical processes were monitored by cyclic voltammetry (CV), AFM, and field-emission SEM. The AuNP deposition was studied as a function of the gold salt concentration, applied overpotential, and pulse time. The results showed that the most dominant factor in controlling the AuNP morphology was the gold salt concentration. The TTFBr and KCP crystals were synthesized on the gold nanoparticle-decorated HOPG electrode following the literature conditions. The electrocrystallization of TTFBr and KCP displays preferential nucleation on the AuNP seed rather than on the planar HOPG electrode. The resulting crystal size was confined and controlled by the salt concentration, AuNP size, and AuNP shape. Nanorods as small as 7 nm in height were nucleated on AuNPs of 20 nm in height. The nanoconfinement effect is attributed to the local curvature of the seed particle that imposes an interfacial strain, thus limiting the cross-sectional dimension of the ensuing organic crystal. This study contributes to the understanding of electrocrystallization at the nanoscale and a solution-based method to incorporate nanorods and nanowires into nanodevices.