Preparation, Characterization And Electrochemical Properties Of H₂O₂Based On Graphene Nanocomposites

Graphen (GNs), found as a new substance in the carbon family materials, it ishigher than the graphite on surface and conductivity, and it also has higher electriccatalytic performance to some specific substrate, caused the people a broad range ofinterests. Nano Pd (Pd-NPs) which has excellent chemical stability, high catalyticactivity, conductivity and strong corrosion resistance, is widely used in REDOXreaction to test object analysis. Meanwhile nano Fe2O3is a kind of horseradishcatalase substance, and also play catalysis of H2O2. Therefore, this dissertationinvolved three types of nano materials, and charactered on the material structure,characteristics and electrode assembly process for functional interface. And then thecharacterization of the modified electrodes was researched in the electrochemicalproperties and catalytic mechanism for H2O2.1. We first synthesized the Graphene Oxide and the Pd-NPs/GNs nanocompositesby one step reduction method. Pd Nanoparticles (~5nm) dispersed homogeneously atthe surface of GNs or embedded inside GNs layers, which not only behavior to GNsdispersion, and also make it with bigger specific surface area and better interlayerconductive properties. Pd-NPs/GNs modified electrodes significantly reduce the overpotential, and enhance the electronic transmission rate between graphite layers. Theresults showed that on the electrode surface H2O2for adsorption processes, andelectrode reaction for two electronic and two protons in electrochemical process. Peakcurrent and the concentration of H2O2presents good linear relationship from1.0×10-9to1.0×10-7mol/L with a correlation coefficient is0.9903, which makes the detectionlimit reach2.0×10-10mol/L.2. Through the electrostatic attraction among negatively charged Polyvinylpy-rrolidone (PVP)-GNs, positively charged poly two allylic two methyl ammoniumchloride (PDDA) and Pd-NPs packaged with negatively charged citric acid, the layersof self-assembly Pd-NPs/PDDA/PVP-GNs nanocomposites were formed. Themodified electrodes present higher electrocatalysis to H2O2. A good linear relationshipbetween anodic peak current and H2O2concentration was obtained in the range of 7×10-8~5×10-6mol/L with the detection limit of1.0×10-8mol/L(R2=0.9956). Themodified electrode shows good selectivity, high stability and great reproducibility.3. Fe2O3, ionic liquid (IL) and GNs were used to bulid Fe2O3-IL-GNs modifiedglassy carbon electrode by a combination method, and was applied to H2O2tests. Thismethod has the following advantages:(1) Fe2O3nanoparticles plays class horseradishcatalase role, and can electrocatalysis of H2O2.(2) GNs is able be effectively fixed byFe2O3, and meanwhile GNs itself has nano catalytic properties of H2O2.(3) Becauseroom-temperature IL well distributed in nanocomposites, it can further promote thecharge transfer rate betwenn GNs layers, greatly enhances current response, andimprove the detection sensitivity. By the three synergetic effect, the modifiedelectrodes presented well electrocatalysis characteristics to H2O2.When the proposedmethods were applied, a linearity was achieved from8.0×10-8~5×10-6mol/L with adetection limit of6.0×10-9mol/L(R2=0.9964). The electrochemical process is shownas two electronic and a proton in electrode reaction.