Electrostatic-Force-Directed Assembly of Ag Nanocrystals onto Vertically Aligned Carbon Nanotubes

Abstract

A facile dry route electrostatic-force-directed assembly (ESFDA) was used to deposit silver nanocrystals onto the external surface of vertically aligned multiwalled carbon nanotubes (MWCNTs). Charged and nonagglomerated aerosol silver nanocrystals were first produced using a mini-arc plasma source. The nanocrystals were then assembled onto the electrically biased MWCNT array through the enhanced electric field near the CNT surface. The electrostatic field plays a crucial role in the assembly process. Gradients of the nanocrystal size and the nanocrystal areal density along the length of the CNT have been observed, and these are likely due to the variation of the electric field near the CNT surface. The ESFDA technique enables the in situ coating of CNT arrays with nanocrystals to create novel hybrid nanomaterials with tailored properties.

Room‐Temperature Gas Sensing Based on Electron Transfer between Discrete Tin Oxide Nanocrystals and Multiwalled Carbon Nanotubes

“…A fraction of the as-produced nanocrystals from the mini-arc reactor were electrically charged by the arc plasma or through the thermionic emission [40]. The charged tin oxide nanocrystals were assembled onto MWCNTs on the sensor substrate using ESFDA [29,30]. In ESFDA, charged nanocrystals were carried into a gap formed between the grounded tubing for the nanocrystal delivery and the electrically biased CNTs on the interdigitated electrode.…”

“…Such a small size and narrow size distribution on the CNT are attributed to the known intrinsic nanocrystal size selection that occurs during the ESFDA process. [29,30] Figure 1. a) Discrete SnO 2 nanocrystals supported on an individual CNT used as a new gas-sensing platform. Possible gas sensing mechanisms include b) direct adsorption of target gas molecules (e.g., NO 2 ) onto the SnO 2 -CNT surface inducing electron transfer and changing the sensor conductivity (Mechanism 1) and c) catalytic reaction between target gas molecules (e.g., H 2 and CO) and oxygen adsorbates releasing electrons back into the SnO 2 -CNT surface and changing sensor conductivity (Mechanism 2).…”

Facile, noncovalent decoration of graphene oxide sheets with nanocrystals

“…We recently developed a facile and materialindependent dry route electrostatic force directed assembly (ESFDA) for the assembly of nanocrystals onto both randomly dispersed CNTs [27 30] and vertically aligned CNTs [28] without the need for chemical functionalization of CNTs. Here we report the assembly of aerosol nanocrystals (e.g., Ag) onto graphene oxide sheets (generated by simple sonication of graphite oxide (GO) in water) that have their basal planes and edges decorated with oxygen functional groups [31 33], using the ESFDA technique.…”

Absorption Properties of Hybrid SnO2 Nanocrystal-Carbon Nanotube Structures

“…[33][34][35] We have also developed a material-independent dry route based on electrostatic force directed assembly (ESFDA) to assemble aerosol nanocrystals onto CNTs. 36,37 The noncovalent attachment of nanocrystals onto CNTs is likely to preserve the unique properties of low-defect pristine CNTs. Herein, we report on the absorption properties of SnO 2 nanocrystals and hybrid SnO 2 nanocrystal-CNT structures.…”