Application Of Photoelectrochemical Analysis In Mercury And Copper Ion Detection

Mercury,copper and other heavy metal pollution has becoming a serious environmental problem,which is badly endangering the health of human being.Due to the enrichment effect of heavy metals in the food chain,excessive ingestion can endanger human health,such as liver,kidney,digestive system and nervous system damage.At present,the methods used to detect heavy metal ions?mainly in spectroscopy and electrochemical analysis?are cumbersome,expensive instruments,many process of sample processing,and difficult to realize real-time online monitoring.Therefore,it is urgent to find a sensitive and accurate,Fast,economical,simple and real-time detection technology to achieve the effective detection of heavy metal ions.Photoelectrochemical?PEC?detection technology in recent years has emerged.Compared with pure photochemical detection and electrochemical detection,the excitation source?light?is completely separated from the detection signal?current?in this PEC method,which makes the background signal is reduced and the analytical sensitivity is improved.Furthermore,the equipment is simple,low cost and easy to build a small test device.In this paper,a new method of high sensitivity and detection for different heavy metal ions has been successfully established by designing new type photoelectrochemical sensors and chemical sensors.The main focus of this paper is as follows:?1?A novel photoelectrochemical sensor for Hg²⁺based on a multifunctional photosensitizer.First,the N3 dye has excellent photovoltaic properties,so the electrode will show a sensitive photocurrent response under visible light irradiation and the N3 dye is covalently bonded to the electrode through its immobilized groups,which greatly improves the stability of the sensor.Secondly,the target detection ion Hg²⁺can be specifically bound to the photoelectric anode through the coordination between the SCN ligand of the N3 dye and the Hg²⁺,so that the absorption characteristics of the N3 dye and the HOMO/LUMO energy level occurred the significant change,the photocurrent signal was significantly reduced and achieved the sensitivity detection of Hg²⁺.And the constructed PEC sensor showed specificity and stability.In addition,since N3 and N3-Hg²⁺are reversibly interconverted by the displacement reaction,the N-doped TiO₂ NWs photocathodes can be recycled.This paper presents a new method for the further development of high performance PEC sensor for Hg²⁺detection based on the multi-functional molecular photosensitizer which can respond directly to the target substance.?2?Sensitive Photoelectrochemical Detection of Cu²⁺Using CdS Quantum Dots Decorated TiO₂ Nanowires in Combination with a Chemical Reducing Reaction.First,TiO₂ nanowires were prepared by hydrothermal method.Then,CdS quantum dots were successfully modified on the TiO₂ NWs by chemical water bath deposition.So as to the obtained TiO₂ NWs/CdS nanocomposite photoelectric anode,which can produce significant photocurrent response due to the excellent photoelectric conversion performance of CdS.In the presence of Cu²⁺,the ascorbic acid AA in the detection system can rapidly reduce Cu²⁺to Cu⁺and deposited onto the surface of the CdS quantum dots in the form of Cu₂S.The resulting Cu₂S can recombine photoelectrons with holes and make the photocurrent decrease significantly to achieve the target ion sensitive detection.The method also has the advantages of simple structure,quick reaction and good selectivity.?3?A water-soluble and retrievable ruthenium-based probe for colorimetric recognition of Hg??? and Cys.First,a hydrophilic phosphonic acid group is introduced into the bipyridine ligand of the ruthenium complex during the synthesis of the probe 1 to solve the problem that the ruthenium-based probe is poor in water solubility.The probe 1-Hg²⁺complex is then formed by the specific coordination between Hg²⁺and the sulfur atom of the probe SCN group.The material will cause the spectrum of the probe 1 to change significantly to achieve the target ion detection,according to the spectral changes.And because of the stronger affinity of the mercapto group and Hg²⁺,Cys then extracts Hg²⁺in the 1-Hg²⁺complex after the addition of Cys in the solution,so that the probe I is released from the 1-Hg²⁺complex And the recovery profile is restored at the same time,so the formed 1-Hg²⁺complex can act as a effective colorimetric sensor for detecting Cys.At the same time,the color change of the assay can be observed by the naked eye.