Graphene-modified Carbon Fiber Microelectrode: Electrochemical Preparation And Applications In Electrochemical Sensors

Graphene, as a two-dimensional monolayer carbon material, has been widely used in thefield of electrochemistry in recent years due to its extraordinary properties such as excellentelectrical conductivity, large specific surface area and good biocompatibility. Comparedwith carbon fiber microelectrode, graphene modified carbon fiber microelectrode possesseslarger specific surface area and excellent electrochemical catalysis which is caused by theintroduced graphene. To testify the feasibility of GCF as a matrix like conventional carbonglassy electrode for the preparation of electrochemical sensors, it is significant toinvestigate the electrochemical sensors based on GCF composite. From the above, the maincontent of this thesis is divided into the following two parts:1. Graphene modified carbon fiber was successfully fabricated by a novelelectro-deposition method. The amount of electro-deposited graphene sheets could beeasily controlled by deposition time. The prepared graphene modified carbon fibermicroelectrode (GCFME) showed highly sensitive and selective for the detection ofdopamine (DA), and the oxidation peak currents of DA in DPV curves had a linearrelationship with the added H2O2concentration in the range of1.0μM to100.0μM.The detection sensitivity was0.81nA μM-1and the detection limit was0.5μM.2. Homoglobin (Hb) was successfully modified on GCF to fabricate Hb/GCFMEelectrochemical sensor upon a dip method. Direct electron transfer of Hb was obtainedon GCF and Hb showed good catalytic activity to H2O2. The electrocatalytic activity ofHb on GCF towards the reduction of H2O2was investigated by amperometrictechniques. The reduction currents had a linear relationship with the added H2O2concentration in the range of8.0to214.0μM. The detection limit was estimated to be2.0μM, and the Michaelis-Menten constant (Kmapp) was calculated to be0.08mM.Moreover, different kinds of materials were modified on GCF, such as enzyme, doublesalt, conducting polymer and metal nanoparticles. All of these materials showed goodelectrochemical activities, suggesting that GCF can be used as a universal matrix for thefabrication of electrochemical sensors.