Electroanalytical applications of a graphite–Au nanoparticles composite included in a sonogel matrix

A novel sonogel composite stably including graphite grains studded with Au nanoparticles (AuNPs) has been synthesised with the aim of obtaining an electrode characterised by electrocatalytic activity, reduced surface passivation and simple and reproducible surface renewal. The impregnation of graphite grains with pre-synthesised AuNPs constitutes a valid approach to stably fix a high amount of AuNPs in such an inorganic matrix. As verified by TEM images, AuNPs fixed on carbon grains surface maintain their individual nature, constituting the basic feature for exerting their electrocatalytic and antifouling properties at best. The electrode was characterised through morphological and electrochemical investigations, demonstrating the uniform distribution of AuNPs on the surface and at different depth of the bulk. Finally, electrochemical tests carried out on the cathodic reduction of H2O2 and on the anodic oxidation of glucose demonstrate the electrocatalytic activity of the AuNPs, the high repeatability of the responses obtained and the reproducibility of the electrode systems, simply restored by routine mechanical cleaning procedure. At variance with many non-enzymatic electrode systems developed for glucose determination, the sensor proposed is suitable for the determination of such a species even at the physiologic neutral pH.