One-Dimensional Carbon Nanotube/SnO2/Noble Metal Nanoparticle Hybrid Nanostructure: Synthesis, Characterization, and Electrochemical Sensing

Herein we report a facile and efficient method for self-assembling noble-metal nanoparticles (NPs) to the surface of SnO2-coated carbon nanotubes (CNT@SnO2) to construct CNT@SnO2/noble metal NP hybrids. By using SnCl4 as the precursor of the SnO2 shell on the surface of CNTs, the hydrolysis speed of SnCl4 was slowed down in ethanol containing a trace amount of urea and water. The coaxial nanostructure of CNT@SnO2 was confirmed by using X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). It was found that the coating layer of SnO2 was homogeneous with the mean thickness of 8 nm. The CNT@SnO2/noble-metal NP hybrids were obtained by mixing noble-metal NPs with as-prepared CNT@SnO2 coaxial nanocables by means of a self-assembly strategy. With the amino group terminated, the CNT@SnO2 coaxial nanocable can readily adsorb the as-prepared noble-metal NPs (Au, Ag, Au-Pt, and Au-Pd NPs). The presence of an amino group at the surface of SnO2 was proved by use of X-ray photoelectron spectroscopy (XPS). In addition, H2O2 sensing by amperometric methods could serve as detection models for investigating the electrocatalytic ability of as-prepared hybrid materials. It was found that wide linear ranges and low detection limits were obtained by using the enzyme-free CNT@SnO2@Au-Pt modified electrode, which indicated the potential utilizations of the hybrid based on CNT@SnO2 for electrochemical sensing.