Bottom-up synthesis of ultrathin straight platinum nanowires. Electric field impact

We present a study of the electric field effect on electrochemically grown ultrathin, straight platinum nanowires with minimum diameter of 15 nm and length in the micrometer range, synthesized on a silicon oxide substrate between metal electrodes in H2PtCl6 solution. The influence of the concentration of the platinumcontaining acid and the frequency of the applied voltage on the diameter of the nanowires is discussed with a corresponding theoretical analysis. We demonstrate for the first time that the electric field profile, provided by the specific geometry of the metal electrodes, dramatically influences the growth and morphology of the nanowires. Finally, we provide guidelines for the controlled fabrication and contacting of straight, ultrathin metal wires, eliminating branching and dendritic growth, which is one of the main shortcomings of the current bottom-up nanotechnology. The proposed concept of self-assembly of thin nanowires, influenced by the electric field, potentially represents a new route for guided nanocontacting via smart design of the electrode geometry. The possible applications reach from nanoelectronics to gas sensors and biosensors

Dielectrophoretic growth of platinum nanowires: Concentration and temperature dependence of the growth velocity

The growth velocity of platinum nanowires in an aqueous solution of K 2PtCl 4 is investigated as a function of the metal complex concentration and temperature. The solution is specially prepared to provide mainly the neutral complex cis-[PtCl 2(H 2O) 2] for growing nanowires by dielectrophoresis. The measured growth velocities indicate diffusion-limited nanowire growth at low concentration and high temperature in qualitative agreement with a theoretical analysis that includes the diffusion of metal complexes and the dielectrophoretic force on the complexes. At concentrations greater than 100 M and low temperature, different behavior is observed, suggesting the growth rate to be limited by the deposition reaction of platinum at the nanowire tip. The enhancement of the K + concentration is found to support nanowire growth. Possible reasons for a rate limitation and for the difference between observed and calculated nanowire growth velocities are discussed

Dielectrophoretic Growth of Platinum Nanowires: Concentration and Temperature Dependence of the Growth Velocity

The growth velocity of platinum nanowires in an aqueous solution of K₂PtCl₄ is investigated as a function of the metal complex concentration and temperature. The solution is specially prepared to provide mainly the neutral complex <i>cis</i>-[PtCl₂(H₂O)₂] for growing nanowires by dielectrophoresis. The measured growth velocities indicate diffusion-limited nanowire growth at low concentration and high temperature in qualitative agreement with a theoretical analysis that includes the diffusion of metal complexes and the dielectrophoretic force on the complexes. At concentrations greater than 100 μM and low temperature, different behavior is observed, suggesting the growth rate to be limited by the deposition reaction of platinum at the nanowire tip. The enhancement of the K⁺ concentration is found to support nanowire growth. Possible reasons for a rate limitation and for the difference between observed and calculated nanowire growth velocities are discussed