Novel graphene-gold nanohybrid with excellent electrocatalytic performance for the electrochemical detection of glucose

• Graphene-gold hybrid with 3D and orientated pores and high catalytic activity.
• The unique porous structure greatly improves the mass transport of electrolyte.
• Monodisperse GNs enhances the electrical conductivity and catalytic activity.
• The sensor exhibits an ultrasensitive electrochemical response towards glucose.
• The study provides promising approach for the fabrication of graphene-metal hybrids.

Graphene-gold nanohybrids have become a hot research topic in material science, because the hybridization can be an effective strategy to enhance the functionality of materials and the integration of nanomaterials on graphene nanosheets potentially paves a new way to improve their electronic, chemical and electrochemical properties. The study reported a novel graphene-gold nanohybrid with excellent electrocatalytic performance for electrochemical detection of glucose. First, the monodisperse gold nanoparticles (GNs) were prepared via the citrate reduction associated with pH-shifting. The resulting GNs give an average particle size of 6 nm and narrow size distribution. Then, one part of the GN solution was mixed with the graphite oxide solution, which followed by the ascorbic acid reduction and unidirectional freeze-drying to prepare graphene aerogel@GNs (GA@GNs). The formed GA@GNs offers a well-defined three-dimensional and orientated porous structure. In addition, the most of GNs in the aerogel was embedded in the intertwined graphene sheets. Finally, another part of the GN solution was sucked into the GA@GNs to obtain GA@GNs/GNs. It was subjected to freeze-drying and thermal annealing in air at 180 °C to remove the citrate modified on the surface of GNs. Because their active sites were well exposed outside, the adsorbed GNs are of high catalytic activity. The study shows that the as-prepared GA@GNs/GNs gives high electrical conductivity (15.4 S m−1), specific surface area (291.6 m2 g−1) and apparent heterogeneous electron transfer rate constant (14.8 ± 0.12 cm s−1). The sensor based on the GA@GNs/GNs displays ultrasensitive electrochemical response to glucose, owing to largely enhanced electron transfer, mass transport and catalytic activity. Its peak current linearly increases with the increase of glucose in the range from 0.01 to 16 mM with the detection limit of 0.004 mM (S/N = 3). The analytical method presents the advantage of sensitivity, repeatability and stability compared with present glucose sensors. It has been successfully applied in the detection of glucose in serum samples with the spiked recovery of 95.7–104.2%. The study also provides a promising approach for building on various graphene-metal nanohybrids with excellent electrochemical performance for sensing, catalysis and energy storage/conversion devices.

The study reported a novel graphene-gold nanohybrid with an excellent electrocatalytic performance. Its unique structure creates a fast electron transfer and mass transport, and high electrocatalytic activity. The sensor based on the nanohybrid provides an ultrahigh sensitivity of electrochemical detection of glucose.Figure optionsDownload as PowerPoint slide