The Construction Of Three-dimensional Hierarchical Transition Metal Composites And Their Enzyme-free Glucose Sensing Properties

With the increasing incidence of diabetes in the world,accurate measurement of glucose content in human blood becomes more and more significant for the diagnosis and control of diabetes mellitus.Electrochemical enzyme-free glucose sensor has been widely used because of its high sensitivity,good selectivity,low detection limit,short response time,easy miniaturization and so on.Electrode material is the core factor affecting the performance of electrochemical sensor,and the performance of electrode material is determined by its chemical composition and microstructure.Therefore,based on the transition metal nanomaterials,which have strong redox properties,good stability,and good catalytic activity for glucose,several three-dimensional hierarchical composite materials are prepared in this paper.First,a hierarchical structure Au@NiCo LDH was compounded by noble metal and double hydroxide through microstructure designing.The material modified glassy carbon electrode as glucose sensor showed good sensing performance.Because the application of powder materials requires the use of a binder and an electrode carrier,a copper foam carrier was introduced in subsequent studies to further study transition bimetal（hydrogen）oxide composites based on copper foam.Copper foam has porosity,high conductivity,and can provide a large amount of copper,which effectively enhances the sensitivity of the electrode material and improves the sensing performance.The research contents are as follows:1. A three-dimensional（3D）rhombic dodecahedron ZIF-67 was prepared by mixing metal ions and organic ligands,and then annealed.The 3D hierarchical hollow core-shell structure composite（Au@NiCo LDH）with 2D NiCo LDH nanosheets as shell and Au nanoparticles（Au NPs）as core was synthesized by acid etching and doped with a small amount of noble metals,which modified with glassy carbon electrode for electrochemical enzyme-free glucose sensing.Au@NiCo LDH electrode showed good sensing performance for electrochemical enzyme-free glucose sensing.range of 0.005-12 m M.The electrode has good anti-interference ability for glucose detection.2. With copper foam as substrate,the copper hydroxide nanowires were grown in situ on the surface of 3D porous copper foam by oxidation method,and then the transition metal hydroxide with two-dimensional structure was grown on copper hydroxide nanowires by hydrothermal method.The bimetallic hydroxide M（OH）_x/Cu（OH）₂/CF（M=Ni,Co,Fe and Zn）with three-dimensional hierarchical structure was prepared.The experimental results show that M（OH）_x/Cu（OH）₂/CF（M=Ni,Co,Fe and Zn）has good catalytic performance for glucose oxidation.Taking Ni（OH）₂/Cu（OH）₂/CF as an example,in the detection range of 0.005-1.0 m M,the detection sensitivity can reach 9351μA·m M^-1·cm^-2,detection limit of 0.5μΜ（S/N=3）,and the anti-interference performance is good,so it can be directly used in the detection of real blood samples.3. On the basis of experiment 2,bimetallic hydroxide based on copper foam was calcined to bimetallic oxide,and its morphology and structure were analyzed and its catalytic performance was tested.The results show that MO_x/Cu O/CF（M=Ni,Co,Fe,Zn）have good catalytic performance in glucose oxidation.Among them,Co₃O₄/Cu O/CF electrode performs the best.Its detection sensitivity can reach 9163.8μA·m M^-1·cm^-2 within 0.005-12 m M,and it has good anti-interference performance.