Research On Electrocatalysts For High Selective Hydrogen Peroxide Reduction And Biosensor Application

Electrochemical biosensors have been widespread used in disease diagnoses,environmental monitoring,and other fields.With the presence of oxygen,oxidase can catalyze target analytes and generate hydrogen peroxide,the electrochemical measurement of which can be used to determine the concentration of target analytes.However,the detection of hydrogen peroxide is generally based on anodic approach that requires applied potential as high as+0.6 V,resulting in oxidation of many endogenous and exogenous substances,impairing assay selectivity.Using the principle of hydrogen peroxide cathodic detection,the influence of these interfering substances can be naturally avoided.However,when hydrogen peroxide is reduced,oxygen is reduced simultaneously on commonly used stable noble metal electrocatalysts,of which the reduction potentials are almost overlapped.With the fluctuation of oxygen concentration,the output current produces corresponding changes,limiting the detection accuracy and practical application of the cathodic detection principle.Therefore,designing oxygen-tolerant electrocatalysts with high selectivity to hydrogen peroxide reduction reaction is essential to the development to high-performance electrochemical biosensors.In this paper,a series of high-selective oxygen-tolerant electrocatalysts for hydrogen peroxide electroreduction were prepared by depositing a thin layer of chromium oxide on the surface of noble metal nanoparticles.Applications of these catalysts on electrochemical biosensor were also discussed.The main research contents are outlined as follows:1.The noble metal/chromium oxide electrocatalysts were prepared by using an electrochemical deposition approach.A series of oxygen-tolerant hydrogen peroxide electrocatalysts were obtained by optimizing the thickness of CrOx layer.Then,the mechanism of the selectivity of electrocatalysts towards hydrogen peroxide reduction was further explored.After that.these electrocatalysts-based electrode was integrated into electrochemical sensors and used for hydrogen peroxide detection,the interference of oxygen concentration fluctuation and endogenous and exogenous electroactive substances,as well as stability and reproducibility were systematically examined.2.A series of electrochemical biosensors with high detection selectivity were constructed by loading oxidase enzyme onto Pt/CrOx,a sample electrocatalysts.Since hydrogen peroxide can be reduced selectively,the current declining caused by oxygen consumption in oxidase reaction was avoided,guaranteeing the final output of biosensors was linear related to peroxide concentration,enzymatic reaction product,realizing the high selective bioassays of glucose,ethanol,choline,sucrose,lactic acid,and uric acid.The non-invasive bioassay was also simulated by using artificial sweat.