Direct Current Plasma-Sputtered Gold Nanoparticles/Carbon Nanosheets Nanohybrid Structures for Electrochemical Sensors

Multifunctional nanohybrid materials such as gold (Au) nanoparticles attached to the carbon nanostructures can be incorporated into devices for in vivo/in vitro detection of various analytes, catalysis and imaging purposes. In this work, vertically aligned carbon nanosheets (CNS) were grown over silicon substrate, followed by direct current plasma-sputtered deposition of Au for different times. The Au-CNS hybrid nanostructures so produced were characterized for surface and cross-sectional morphologies, phase composition and surface chemistry by means of scanning electron microscope, x-ray diffraction and x-ray photoelectron spectroscope techniques. The Au-CNS exhibit vertically aligned, dendritic wall morphology with different degrees of dispersion on the substrate. The electrochemical (EC) behavior of the different Au-CNS samples was investigated for application as electrochemical transductors. The EC activity was investigated by both cyclic voltammetry and electrochemical impedance spectroscopy in the presence of [Fe(CN)₆]^3−/4−. The variations in active surface area and roughness of different electrodes were evaluated in order to explore application of such Au-NS in the EC biosensors operating via the direct electron transfer process. The EC results show remarkable properties such as high diffusion coefficient (D_o), low peak-to-peak separation value (ΔE) for the oxidation and reduction processes of the [Fe(CN)₆]^3−/4− redox system and low surface resistivity. Such Au-CNS nanohybrid structures are promising for use in photoelectrochemical cells, sensing devices, catalysis, surface-enhanced Raman spectroscopy and biotechnology applications.