MOFs Template Synthesis Of Transition Metal Oxygen/sulfide Materials And Their Glucose Electrochemical Sensing Properties

Diabetes is a dangerous disease caused by glucose metabolism disorders and is a metabolic disease characterized by high blood glucose.Hyperglycemia is usually a blood glucose level higher than 11.1 mmol/L,but it is not until the blood glucose concentration reaches a higher value(15-20 mmol/L)that the symptoms may begin to become obvious.Long-term high blood glucose can cause the failure of various organs and tissues.If left untreated,it can cause serious health problems,such as stroke,cardiovascular disease,chronic kidney disease,foot ulcers,and eye damage,which will significantly increase diabetic morbidity and mortality,and bring heavy economic burdens to individuals and countries.Diabetes has become one of the most common and serious threats to human health.Glucose is considered a key intermediate product in the metabolic process,and its concentration at each stage of the metabolic process is directly related to human health.During the diagnosis,treatment,and control of related diseases,it is necessary to monitor the concentration of glucose in body fluids.To diagnose diabetes and monitor blood glucose levels quickly in real-time,many sensors have been researched and developed to test the blood glucose level.In addition to clinical diagnosis,the importance of glucose testing in the biotechnology and food industries has also attracted attention.Therefore,the development of effective detection methods with high sensitivity,high selectivity,and low cost has become an important scientific and technical hot topic.Compared with other detection methods,electrochemical technology has high sensitivity,good selectivity,and easy operation,and is a promising method for constructing simple and low-cost sensors.The development of fast and reliable glucose monitoring sensor devices for the treatment and control of diabetes has always been a hot topic of electroanalytical chemistry.Electrochemical glucose detection methods include enzyme-based electrochemical sensors,and electrochemical non-enzyme sensors.In the past few decades,electrochemical sensors based on glucose oxidase have received widespread attention.Many studies have involved the use of glucose oxidase for the construction of various glucose detection biosensors.Glucose oxidase specifically catalyzes the oxidation of glucose to glucose lactone.Although enzyme-based sensors have high selectivity and excellent sensitivity,they have the following problems:(1)The inherent characteristics of enzymes,they lack stability;(2)The difficulties of immobilizing enzymes,they lack simplicity(3)H2O2 generated by oxidase requires high overpotential and is susceptible to interference from other redox active molecules such as ascorbic acid(AA).To solve the above problems,electrochemical non-enzymatic glucose sensors have attracted great interest due to their low cost,easy operation,and good stability.The electrochemical non-enzymatic glucose sensor is considered to be a more promising method for glucose detection.Transition metal oxides are often used to construct non-enzymatic glucose electrochemical sensors.Many transition metal oxides(Fe3O4,MnO2,Co3O4,NiO,ZnO etc.)can be used as catalysts with good electrocatalytic activity,low cost,and environmentally friendly features.There are many ways to synthesize these catalysts,such as the hydrothermal method,redox method,electrodeposition method,template method,and so on.With MOF as the precursor,no external template is required.The MOFs derivative material prepared by high-temperature calcination can keep the morphology unchanged and produce a rich porous structure.Therefore,electrochemical sensors based on MOFs derivatives have more obvious advantages.In this paper,MOFs prepared by a solvothermal method is used as a template to synthesize transition metal oxides by high-temperature annealing,and the MOFs precursor is sulfurized to obtain transition metal sulfides.In the research of electrochemical glucose sensing,among the synthesized materials,cobalt nickel oxide(Ni-Co-3)and copper-cobalt sulfide(Co-Cu-2)have good electrochemical catalytic performance for glucose detection.The specific work research is as follows:1.Through a simple hydrothermal method and subsequent calcination,the layered NiO nanorods assembled by nanoparticles and the microflowers assembled by nanosheets have been successfully synthesized.During electrochemical tests,NiO nanorods and NiO micro-flowers modified glassy carbon electrodes(GCE)both show excellent performance in detecting glucose.The linear equations fitted by NiO nanorods and NiO micro flower electrodes are I(?A)=0.1184C(?M)+11.7184(R2=0.9960)and I(?A)=0.1129 C(?M)+5.8705(R2=0.9989).The linear ranges are 0.0018-4.65 mM and 0.0018-3.65 mM,respectively.In addition,the low detection limits of NiO nanorods and micro-flowers electrodes are calculated to be 0.7 and 0.8?M,respectively,and the corresponding sensitivities of the two NiO electrodes are 1677.5 and 1598.9 ?A·mM-1·cm-2,respectively.2.Using Ni(NO3)2·6H2O,Co(NO3)2·6H2O and H4DOBDC(2,5-dihydroxyterephthalic acid)as raw materials,a series of different nickel and cobalt molar ratios were synthesized via solvothermal method,denoted as Ni-Co-MOF-1,Ni-Co-MOF-2,Ni-Co-MOF-3.Furthermore,different ratios of nickel and cobalt oxides(Ni-Co-1,Ni-Co-2,Ni-Co-3)were produced by followed calcination at 350? for 2 h.The electrochemical glucose sensing performance of Ni-Co-1,Ni-Co-2,and Ni-Co-3 at 0.45,0.50,0.55,and 0.60 V potential was tested respectively.By comparison with the other samples,the Ni-Co-3 microtubes modified electrode exhibits excellent electrochemical performance at a working potential of 0.55 V(0.1 M NaOH).The sensor constructed by this material is fitted with a linear equation at 0.60 V potential:I(?A)=0.075C(?M)+12.84(R2=0.9970),and the calculated sensitivity is:1062.32?A·mM-1·cm-2,the linear range is 0.001-3.67 mM,and the detection limit is 0.5 ?M.3.A series of Co-Cu-MOFs were synthesized by a simple solvothermal method,using Cu(NO3)2·6H2O,Co(NO3)2·6H2O,H4DOBDC as raw materials,and the molar ratio of Co/Cu is 8:2,7:3,and 0:1.The copper/cobalt sulfide micro-spindle structures(Co-CuS-1,Co-CuS-2,Co-CuS-3)with different ratios of Co/Cu were obtained by further sulfuration process at 110?.The electrochemical glucose sensing performance of Co-CuS-1,Co-CuS-2,Co-CuS-3 was tested by cyclic voltammetry and chronopotentiometry.The sensor shows excellent electrochemical sensing performance.At a potential of 0.55 V,the linear equation fitted by the electrochemical glucose sensor constructed with this material is:I(?A)=0.1004C(?M)+13.57(R2=0.9972),The linear range of detection is 0.001-3.66 mM,The calculated sensitivity is 1422.09 ?A·mM-1·cm-2,and the detection limit is 0.1 ?M(S/N=3).