| Abstract [eng] |
Graphene a two-dimensional one atom thickness of graphite comprises of sp2 carbon atoms which are tightly packed into a honeycomb crystal lattice. This compound has remarkable physical, chemical, and mechanical properties with values that surpass those obtained in any other materials, enabling them to be used in a wide range of applications. Despite these exceptional properties this compound possess, having a zero band-gap restrain its use in electrocatalaysis and sensing applications. This problem could be overcome by chemically doping graphene with heteroatoms. The doping of graphene with N and S was achieved by hydrothermally treating GO with NH4SCN and different amount of pyrrole to obtain a sponge-like monolith graphene nanocomposite NS-G. This nanocomposites were characterized using SEM, FTIR, XPS and Raman spectroscopy. SEM images of NS-G reveals this nanocomposite to have rough curled edges due to defective sites form during heteroatoms doping. FTIR revealed functional groups on the modified material. Some peaks disappear or decrease in intensity, while other peaks appear or increase in intensity. The FTIR spectra confirm the presence of C=N, CN, and C-S bonds indicating that the doping of nitrogen and sulphur atoms has successfully entered the GO structure. XPS analysis further confirm a successful doping by displaying peaks of C, O, N, and S, and showing the atomic percentages for elemental analysis. In the Raman spectra, the ID/IG ratio increases with increased modification indicating disorder in the nanocomposite. The electrochemical analysis of NS-G was carried out by cyclic voltammetry and chronoamperometry. Although NS-G and GO control had the same potential window, the current peak of NS-G was way higher than the GO control. The reduction FAD and oxidation of FADH2 was identified by the cathodic and anodic currents respectively. Chronoamperometry increase linearly till 2.5 mM of glucose. The NS-G could function as a glucose biosensor with linear range of 0.5 mM to 2.5 mM, a sensitivity of 6.9476 µA*mM-1*cm-2, and limit of detection of 0.4911 µM. |
