Catalysis, Nano-zno Preparation, Characterization, And Its Modified Electrode On The Power Of Biological Molecules

In the investigation of biosensors and biofuel cells, the immobilization of biomacromolecules is an important research area. Furthermore, the selection of the carriers is important for the immobilization of biomacromolecules. Considering that as a inorganic semiconductor material, ZnO is a cheap nanoparticles with simple preparation method to obtain the cheap nanoparticles and large special surface area, in this thesis, the preparation, characterization of ZnO nanoparticles as well as the preparation and electrochemical and electrocatalytic performances of HRP and GO_X immobilization on the ZnO nanoparticles modified electrode were investigated. The main results are as follows:1. ZnO nanoparticles were synthesized using the direct precipitation method. the morphology, structure and performance of ZnO nanoparticles were characterized by the analysis of XRD, EDS and TG etc., It was found that ZnO prepared with the direct precipitation method possessed the porous nanoparticles with the square conical shape, uniform particle size and good dispersity. The average size of the ZnO nanoparticles was about 65 nm. The special surface area was 43 m²/g and the pore diameter was 4 nm.2. The electrochemical and electrocatalytic performances of HRP immobilized on the surface of the ZnO-DMSO modified GCE were investigated. The results demonstrated that HRP immobilized on the ZnO-DMSO modified GCE was not denatured and could undergo the direct and quasi-reversible electrochemical reaction. The formal potential was -228 mV. And the formal potential was linearly proportional with the pH of the solution and it demonstrated that one electron and one proton participated in the direct electrochemical reaction of HRP. The electron transfer rate constant (k_s) was 3.95±0.89 s^-1, which was much larger than those reported in the literatures. HRP immobilized on the ZnO-DMSO modified GCE could undergo fast electron transfer because of the coordination of DMSO and ZnO. In addition, it was found that HRP immobilized on the ZnO-DMSO surface showed the good electrocatalytic activity, stability and repeatability for the reduction of H₂O₂.3. The electrochemical and electrocatalytic performances of GO_X immobilized on the surface of the ZnO modified GCE were investigated. The results demonstrated that GO_X immobilized on the ZnO modified GCE was not denatured and could undergo the direct and quasi-reversible electrochemical reaction. The formal potential was -456 mV, and the formal potential was linearly proportional with the pH of the solution and it was demonstrated that two electrons and two protons participate the direct electrochemical reaction of GO_X. The electron transfer rate constant (k_s) is 39.2±7.2 s^-1, which was much larger than those reported in the literatures, indicating that ZnO showed good action for the electrochemical reaction of GO_X. In addition, it was found that GO_X immobilized on the ZnO surface showed the good electrocatalytic activity for the reduction of O₂. When glucose was added into the solution, the current of the cathodic peak for the reduction of O₂ would be linearly decreased. It showed a good sensitivity. Therefore, it could be used to construct a new type of glucose sensor based on O₂ comsuption. The GO_X modified electrode could be also used in the biofuel cell. Thus, it is GO_X modified electrode that has good applicable future.