Preparation Of Cobalt-based Nano Composite Catalysts And Their Applications For Enzyme-free Glucose Sensors

Diabetes has become a global health challenge,with 537 million adults living with diabetes worldwide in 2021.In order to be better treated,people with diabetes must strictly control their blood sugar to prevent serious complications from rising blood sugar.For decades,there has been growing demand for glucose sensors with high sensitivity,high selectivity,good stability and low cost.So far,commercial glucose sensors are generally based on enzyme（glucose oxidase or glucose dehydrogenase）and glucose electrochemic-enzymatic method,but they also have many problems,such as lack of stability,high cost and complex manufacturing process,and enzyme activity is easily affected by external environmental factors.All these have hindered and limited their wide use in the field of glucose detection.In recent years,non-enzyme glucose sensors based on low-cost transition metals have become research hotspot due to their excellent catalytic performances.It is critical important to improve catalytic performances by increasing the number of active sites,promoting synergistic reaction and improving the contact between electrolyte and catalyst.In this study,cobalt-based materials were used to compound with other materials,and the synergistic effect between heterogeneous metals was utilized to prepare catalysts with excellent catalytic effects on glucose.The main contents are as follows:（1）Using melamine cyanurate（MCA）as template,bimetallic nanoparticles were added to synthesize Co Cu-melamine-cyanurate hexagon prism precursor（Co Cu/MCA）by a simple solvothermal method.Nitrogen-doped carbon seaweed nanosheets（Co Cu@MC）were synthesized by pyrolysis of Co Cu/MCA.The morphology of pyrolysis products was controlled by adjusting species of metal ions in hexagon prism precursor.The pyrolysis of Co/MCA and Cu/MCA respectively formed carbon nanotubes（Co@MC）and flocculent clusters（Cu@MC）.Co Cu@MC showed better catalytic glucose oxidation performances than Co@MC and Cu@MC.The sensitivity of Co Cu@MC electrode material for glucose detection was 1449μA m M^-1 cm^-2,while detection limit was 0.34μM and linear range was 1μM～1250μM.In addition,the Co Cu@MC sensor demonstrated good anti-interference,reproducibility and stability.（2）The CuCo₂O₄@Ni Co₂O₄ heterogeneous nanoarray electrode was prepared by hydrothermal and calcination methods.Unique nanostructure reduced the activation energy of electron transfer,shortened the migration path among ions,promoted electron transfer and improved electrocatalytic activity.With the synergistic effect of components,as-prepared electrode materials showed good electrochemical characteristics.As enzyme-free glucose sensor electrode material,the sensitivity of CuCo₂O₄@Ni Co₂O₄was 1549.32μA m M^-1 cm^-2,the linear range was 1μM to 2150μM（R²=0.9934）,the detection limit was 0.28μM,and the response time was less than 1 s.（3）Highly ordered three-dimensional layered Ni Co₂O₄ NWS@Ni Co₂O₄ NWE core-shell nanocone arrays were synthesized by a two-step hydrothermal method using copper foam as a conductive substrate.Unique nanostructure consisted of Ni Co₂O₄nanocone coated with Ni Co₂O₄ nanosheets.The catalytic performance of prepared electrode in glucose oxidation was studied by cyclic voltammetry and amperometry.Ni Co₂O₄ NWS@Ni Co₂O₄ NWE electrode showed good sensitivity to glucose(7641μA m M^-1 cm^-2),wide linear range（1μM～1250μM）,low detection limit（0.16μM）and fast response time（1 s）.