Carbon Nanotube/Silica Coaxial Nanocable as a Three-Dimensional Support for Loading Diverse Ultra-High-Density Metal Nanostructures: Facile Preparation and Use as Enhanced Materials for Electrochemical Devices and SERS

Abstract

In this paper, we have reported a very simple strategy (combined sonication with sol−gel techniques) for synthesizing well-defined silica-coated carbon nanotube (CNT) coaxial nanocable without prior CNT functionalization. After functionalization with NH2 group, the CNT/silica coaxial nanocable has been employed as a three-dimensional support for loading ultra-high-density metal or hybrid nanoparticles (NPs) such as gold NPs, Au/Pt hybrid NPs, Pt hollow NPs, and Au/Ag core/shell NPs. Most importantly, it is found that the ultra-high-density Au/Pt NPs supported on coaxial nanocables (UASCN) could be used as enhanced materials for constructing electrochemical devices with high performance. Four model probe molecules (O2, CH3OH, H2O2, and NH2NH2) have been investigated on UASCN-modified glassy carbon electrode (GCE). It was observed that the present UASCN exhibited high electrocatalytic activity toward diverse molecules and was a promising electrocatalyst for constructing electrochemical devices with high performance. For instance, the detection limit for H2O2 with a signal-to-noise ratio of 3 was found to be 0.3 μM, which was lower than certain enzyme-based biosensors. And the detection limit for hydrazine is <0.5 μM, which was lower than amperometric hydrazine sensors based on functional nanomaterials such as zinc oxide nanonails, CNTs-modified electrodes, o-aminophenol grafted GCE electrode, and multilayer film containing cobalt phthalocyanine. Furthermore, the as-obtained high-density gold/silver core/shell NPs supported on coaxial nanocables could be used as a good surface-enhanced Raman scattering (SERS) substrate for the detection of different molecules [4-aminothiophenol (4-ATP) and adenine], showing the great potential of CNT/SiO2/(Au/Ag) as a convenient and powerful SERS substrate for biological tags and biological molecular detection.