(232p) Controlled Synthesis of Organic Nanowires on Gold Nanoparticle Seeds for Sensors Applications

This research focuses on the fabrication of inorganic-organic crystallization using gold nanoparticles (AuNPs) as seeds in order to control potassium tetracyanoplatinate (KCP) or tetrathiafulvalene bromide charge transfer salt (TTFBr) deposition. The AuNPs were first deposited on highly oriented pyrolytic graphite (HOPG) for 0.01 s to 1 s. Then, either 1 to 10 mM TTF or 0.07 mM KCP was deposited on the AuNP decorated HOPG following literature procedures. Both steps were accomplished by electrochemistry. All the depositions were monitored by cyclic voltammetry and atomic force microscope. Field emission scanning electron microscope was employed to image the inorganic-organic system. For depositing AuNPs, the results show that concentration is the key factor to control the size and shape of AuNPs while the applied overpotential and deposition time play a secondary role. The size of the organic crystals grown on AuNP decorated HOPG is smaller comparing with those grown on bare HOPG. Using the same method, we successfully deposited TTFBr and KCP crystals on a gold nanopatterns designed by our lab. The electrical impedance of the sensor was measured by exposing the sensor surface to different gases at different concentrations. The results show that both sensors can detect ppm level toxic or flammable gases, for example, ammonia, within one minute. We plan to develop our sensor further for specific applications. Our work contributes both fundamental understanding of seed-mediated nucleation and technology of low-cost manufacturing of chemical sensors.