Design Of In VO₄-based Photoelectrochemical Sensor With Surface Polarized And Their Activities For Detecting Estradiol

In recent years,estrogen drugs remain in food and the environment due to heavy use in life and production.Among them,estradiol is one of the most active estrogen,even at a very low concentration,estradiol has serious toxic effects on organism,endangering human health.Owing to the large size of existing detection equipment,it cannot not be used for on-site real-time analysis of samples though it is more sensitive and has low detection characteristics.Based on the InVO₄ material,this thesis designs a phosphoric acid-boric acid co-modified InVO₄（BP-IVO）photoelectrochemical sensor to detect estradiol.The main work of this design is as follows:（1）The ultra-thin InVO₄ nanosheet material was successfully prepared by a simple hydrothermal method and co-modified with phosphoric acid-boric acid.A variety of characterization methods was used to reveal the mechanism of the significantly enhanced photoelectric response of InVO₄materials after multiple inorganic acid modification.Phosphoric acid is adsorbed on InVO₄by substituting hydroxyl groups on the surface of InVO₄,and then phosphoric acid and boric acid are connected through glycerol as a"bridge"to achieve BP-IVO.Inorganic acid will ionize in the solution,so that a negative electric field is formed on the surface of InVO₄,which enhance the separation of photo-generated charges.This is due to the rapidly migration of holes which generated under illumination to the surface of the material prompted by the negative electric field,effectively avoiding the recombination of photo-generated charges.Therefore,InVO₄ represent a remarkable photocatalytic performance.（2）BP-IVO photoelectrochemical sensor prepared by spin-coating BP-IVO material on the electrode surface.The phosphoric acid-boric acid co-modification accelerates the separation of electrons and holes.Meanwhile the holes was consumed in large quantities in the detection solution due to the oxidation of estradiol,which did not recombine with the electrons.The electrons are transmitted to the external circuit to form a photocurrent.We established a standard curve of photocurrent and estradiol concentration to detect estradiol.The optimal assay conditions can be obtained by optimizing the estradiol assay conditions.Estradiol was measured in the concentration range of 0.1-200 ng/m L,and a linear relationship was found between estradiol concentration and photocurrent magnitude:?I=0.001317C+0.08766,R²=0.9988,the sensitivity is 0.001317 m A/ng?m L^-1,the detection limit is 0.05 ng/m L.At the same time,experiments prove that the BP-IVO sensor has good selectivity,reproducibility and stability.Finally,by adding standard recovery tests on milk,fish meat,tap water and Yellow River water,the results prove that the recovery rate and relative standard deviation was within a reasonable range,up to the actual testing standard.In addition,it is consistent with the HPLC detection result,which fully proves the reliability of the sensor’s detection result.Hence,the BP-IVO photoelectrochemical sensor designed in this paper has the advantages of fast detection speed,high sensitivity,simple and portable,etc.,and provides a feasible reference for the design of electrochemical sensors for detecting estrogen residues.