Laser and thermal dewetting of gold layer onto graphene paper for non-enzymatic electrochemical detection of glucose and fructose

Electrochemical non-enzymatic detections of glucose and fructose were based on gold nanoparticles (AuNPs) onto graphene paper. Electrodes based on AuNPs have been obtained inducing dewetting, by thermal (furnace) or by laser, of sputter deposited 8 nm-thick Au layer onto graphene paper. The electrodes were characterized by Scanning Electron Microscopy, Micro Raman Spectroscopy, X-ray Diffraction, Rutherford back-scattering Spectroscopy and Cyclic Voltammetry. The main difference exhibited by thermal and laser dewetting processes lies in the size and shape of the resulting gold nanoparticles. Laser dewetting originates smaller particles than that obtained by thermal dewetting. The particles are almost spherical and mainly localized onto graphene nanoplatelets. The size of AuNPs is in the ranges 10-150 nm. Electrodes obtained by thermal process present gold nanostructures characterized by faceted AuNPs. Typical sizes are in the range of 20-40 and 200-400 nm. The electrocatalytic activity toward glucose and fructose oxidation in alkaline phosphate buffer solution are presented and discussed. Glucose was detected at a potential of 0.17 V (laser dewetting) or 0.19 V (thermal dewetting) vs SCE, which corresponds to the intense peak of two electrons oxidation. Fructose was detected at potential of 0.4 V vs SCE. Sensitivity up to 1240 mu A mM(-1) cm(-2) for glucose detection was obtained. The resulting analytical performances for glucose and fructose detection are very promising since comparable to the actual state of art for nanostructured gold electrodes which are, however, produced by complex multi-steps wet processes and/or enzymes.