| Fabrication and application of graphene and metal nanocomposites have become a focus in the field of graphene research. The metal/graphene nanocomposite combines many excellent properties of graphene and metal nanomaterials such as the high catalytic activity of metal nanomatrials and many extraordinary properties of graphene including the larger specific surface area, strong mechanical strength, high conductivity, and good biocompatibility. In addition the excellent properties of graphene may have synergistic effect to the loading materials, which leads to greatly enhanced overall performance of the composites. So, metal/graphene-based composites may have great potential applications in many areas such as fuel cells, supercapacitors, bio-sensors, nano-devices, etc.There are many approaches to prepare the nanocomposites of graphene and metal. But, the synthesis of graphene supported metal nanoparticles with a simple way, in which metal nanoparticles distribute uniformly on the surface of graphene, is still a challenge. During this research, our attention was centered on finding a green, simle but efficient method to synthesize the nanocomposites of graphene and platinum. We focused on the catalytic performance of this nanocomposite to electro-oxidation of methanol and glucose. The application of this nanocomposite in methanol fuel cells and nonenzymatic glucose biosensors was also explored. The main contents and the main conclusions are as follows:Firstly, PtNCs/graphene composite was synthesized within a one-step process in which ascorbic acid was chosen as the reducing agent. The experiment results demonstrated Pt nanoclusters could be well dispersed on the surface of graphene sheet. After that, this composite was evaluated with a series of electrochemical measurements, which directly show that PtNCs/graphene composite exhibits high electrocatalytic ability and stability as the electrochemical catalyst in the electrooxidation of methanol. All these results demonstrated that PtNCs/graphene composite was synthesized by a clean and efficient method, which may have further application in the synthesis of graphene-based nanocomposites. Secondly, to further improve the catalytic activity of Pt, we introduced Polyvinyl-Pyrrolidone (PVP) as dispersing agent during the fabrication of PtNCs/graphene so as to enhance the dispersity of the Pt nanoclusters. The results directly showed that Pt nanoclusters dispersed uniformly on the surface of graphene. After further voltammetric and amperometric tests we were amazed to find that the synthesized PtNCs/graphene exhibited excellent electrocatalytic activity toward glucose oxidation in neutral solution. Current response curve showed a sensitivity factor of8.49μA cm-2mM-1and a wide linear range from1to20mM. This nanocomposite also proved a good resistance to surface poison from absorbed intermediate products or the influence from co-existing electroactive species such as uric acid (UA), ascorbic acid (AA), acetaminophen (AP), etc.Finally, controllable growth of Au nanoparticles on the surface of glassy carbon was studied. Au nanoparticles were successfully prepared on the surface of the glassy carbon plates by the modified seed mediated growth method. The size and density of the gold nanoparticles could be easily tuned through the growth time. Related electrochemical results directly showed that AuNPs/GC has extraordinary electrocatalytic ability toward the oxidation of glucose. The AuNPs/GC electrodes show a wide linear range from0.1mM to25mM with the sensitivity of87.5μA cm-2mM-1and a detection limit down to0.05mM for the detection of glucose. Normal interfering species naturally present in the physiological environment have no obvious effects for the oxidation of glucose on AuNPs/GC electrodes, implying further the promise of AuNPs/GC electrodes in the fabrication of nonenzymatic glucose biosensors. |
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