Research On Enzyme-free Electrochemical Biosensor Based On Nickel Cobalt Phosphide Porous Nanomaterials

Glucose and hydrogen peroxide（H₂O₂）are important life information molecules in the organism,and monitoring the concentration of glucose and H₂O₂ is important to practical significance.The electrochemical sensor has the advantages of high sensitivity,fast speed and low cost,and is an effective method for detecting glucose and H₂O₂.Although the enzyme-based electrochemical sensor has high detection sensitivity and good selectivity,the process of enzyme immobilization on the electrode surface is complicated,and it is easily affected by environmental factors,and its long-term stability is poor.In recent years,enzyme-free electrochemical sensors based on inorganic nanomaterials have been favored by researchers due to their stability and simple preparation.Among them,the electrocatalytic activity of nanomaterials on detection molecules is a decisive factor affecting sensor performance.With abundant reserves of transition metal phosphides and unique semi-metallic properties,it is currently recognized as one of the most outstanding new catalytic materials.In addition to the characteristics of the material itself affecting its electrocatalytic activity,the structure of the material is also closely related to its catalytic activity.Porous nanomaterials can expose more catalytically active sites,promote electron/ion transfer,accelerate the kinetic process of catalytic reactions,and improve the electrocatalytic activity of the material.Based on this,this paper designs and prepares nickel-cobalt phosphide-based nanomaterials with porous structures and constructs high-efficiency enzyme-free electrochemical biosensors.The main research contents and results are as follows:（1）Transition metal cobalt phosphide（CoP）nanocages were prepared by a combination of hydrothermal and calcination methods.Studies have shown that the hollow nanocage structure of CoP has excellent electrocatalytic oxidation activity for glucose.Enzyme-free glucose electrochemical sensor based on CoP nanocage has a wide linear range（0.04-3 m M and 3-8 m M）,low detection limit（3.8μM）and high sensitivity,as well as good selectivity and repeatability,reproducibility and stability.In addition,the sensor can be applied to the rapid detection of glucose in human serum.（2）The study found that the nickel-cobalt bimetallic phosphide（NiCoP）nanocage exhibits excellent electrocatalytic reduction characteristics for H₂O₂ molecules at-0.55 V potential.The linear range of the enzyme-free H₂O₂ electrochemical sensor based on NiCoP nanocage is 0.6-8.8μM and 8.8μM-11.3 m M,and the sensitivity is 1214.36μA m M^-1 cm^-2 and 324.47μA m M^-1 cm^-2,The detection limit is 0.18μM,and it has good selectivity,repeatability,reproducibility and stability.（3）Using three-dimensional porous graphene（GFs）as a carrier,controllable synthesis of NiCoP-supported GFs porous materials（NiCoP/GFs）.Studies have shown that NiCoP/GFs exhibits excellent electrocatalytic reduction properties for H₂O₂molecules at a low overpotential（-0.3 V）.The sensitivity of enzyme-free H₂O₂electrochemical sensor based on NiCoP/GFs is 4398.54μA m M^-1cm^-2,1279.66μA m M^-1cm^-2 and 227.41μA m M^-1cm^-2.The detection limit is 0.028μM,The detection range is 0.2-1.8μM,1.8-10.8μM and 10.8μM-9.33 m M.And the sensor has good selectivity,repeatability,reproducibility and stability.In addition,the sensor can realize the direct detection of H₂O₂ released by living cells.