We report the novel fabrication of a highly sensitive, selective, fast responding, and affordable amperometric glucose biosensor using exfoliated graphite nanoplatelets (xGnPs) decorated with Pt and Pd nanoparticles. Nafion was used to solublize metal-decorated graphite nanoplatelets, and a simple cast method with high content organic solvent (85 wt %) was used to prepare the biosensors. The addition of precious metal nanoparticles such as platinum (Pt) and palladium (Pd) to xGnP increased the electroactive area of the electrode and substantially decreased the overpotential in the detection of hydrogen peroxide. The Pt−xGnP glucose biosensor had a sensitivity of 61.5 ± 0.6 μA/(mM·cm2) and gave a linear response up to 20 mM. The response time and detection limit (S/N = 3) were determined to be 2 s and 1 μM, respectively. Therefore, this novel glucose biosensor based on the Pt nanoparticle coated xGnP is among the best reported to date in both sensing performance and production cost. In addition, the effects of metal nanoparticle loading and the particle size on the biosensor performance were systematically investigated.
xGnP‐Reinforced LLDPE nanocomposites have been prepared using co‐, counter‐ and modified co‐rotating screw systems. The highest tensile strength and modulus were shown in the case of composites made by counter‐rotating screws. The percolation threshold of exfoliated graphite nanoplatelet/LLDPE nanocomposites was between 12 and 15 wt.‐%. The change of crystallinity caused by exfoliated graphite nanoplatelet loading was monitored using DSC and XRD. It was found that solution mixing showed better dispersion of exfoliated graphite nanoplatelets than melt mixing, and counter‐rotating screws produced better dispersion of the exfoliated graphite nanoplatelets than co‐ and modified co‐rotating screws even though bubbling appeared during mixing in the barrel.
Exfoliated graphite nanoplatelets (xGnPs) with an average thickness of 1–10 nm present an inexpensive alternative to carbon nanotubes in many applications. In this paper, stable aqueous suspension of xGnP was achieved by noncovalent functionalization of xGnP with polyelectrolytes. The surfactants and polyelectrolytes were compared with respect to their ability to suspend graphite nanoplatelets. The surface charge of the nanoplatelets was characterized with zeta potential measurements, and the bonding strength of the polymer chains to the surface of xGnP was characterized with Raman spectroscopy. This robust method opens up the possibility of using this inexpensive nanomaterial in many applications, including electrochemical devices, and leads to simple processing techniques such as layer-by-layer deposition. Therefore, the formation of xGnP conductive coatings using layer-by-layer deposition was also demonstrated.
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