Electrochemical sensing performance of nanodiamond-derived carbon nano-onions: Comparison with multiwalled carbon nanotubes, graphite nanoflakes, and glassy carbon

Abstract

Carbon nano-onions (CNOs) are emerging carbon nanomaterials with unique microstructure and electronic properties. CNOs are 0-D carbon analogs of 1-D carbon nanotubes (CNTs) and 2-D graphenes. CNOs are composed of sp2-bonded, concentric nanographene shells surrounding a hollow core. Microstructure, electrochemical properties, and biosensing performances of nanodiamond-derived CNOs (N–CNOs) were studied in comparison with other popular carbon electrodes: multiwalled carbon nanotubes (MWCNTs), graphite nanoflakes (GNFs), and glassy carbon (GC). First, morphology and microstructure of N–CNOs were characterized by scanning and transmission electron microscopies (SEM, TEM), X-ray diffraction (XRD), and Raman spectroscopy. Chemical composition and chemical functional groups were probed by X-ray photoelectron spectroscopy (XPS). Raman spectra of N–CNOs showed a large value of ID/IG, indicating that N–CNOs include defects, i.e., exposed edge planes. Second, electrocatalytic activity of N–CNOs toward oxygen reduction reaction was tested in comparison with MWCNTs, GNFs, and GC. Last, biosensing performances of N–CNOs were studied. Cyclic voltammetric and differential pulse voltammetric measurements were carried out for the detection of redox-active biomolecules such as dopamine, epinephrine, and norepinephrine. The results showed remarkable electrochemical activities of N–CNOs with high sensitivity, high selectivity, and stable electrode responses for the detection of biologically important molecules.