Preparationg And Application Of Photoelectrochemicall Sensor Based On Composite Material

In recent decades,photoelectrochemical?PEC?sensors have achieved rapid development as an emerging detection method.PEC sensors have the advantages of high sensitivity,simple equipment,short detection time,low cost and equipment is easy to miniaturize.But,photoelectrochemical analysis methods are still in their infancy compared with the traditional methods of electrochemical analysis and optical analysis.Therefore,research on sensor element design and signal transmission mechanism still needs to be deeper.And it is of great significance to study the research of PEC sensors by studying the photoelectric active materials with good photoelectric performance,constructing new sensing modes and creating new sensing mechanisms.In this paper,different composite materials were prepared as photoelectric active materials,and sensitive detection of GSH,PFOA and H₂O₂ was realized.?1?A novel glutathione photoelectrochemical sensor based on PbS QDs/TiO₂ NPsGlutathione?GSH?palys an important role in biological functions,such as signal transduction and cell proliferation.In addition,GSH is also closely related to various diseases,such as cancer,cardiovascular disease and so on.Therefore,achieving high-sensitivity detection of GSH has a guiding role in the diagnosis and post-treatment of diseases.In this experiment,TiO₂ NPs were modified to the surface of ITO electrode by high temperature calcination method to prepare TiO₂ NPs/ITO electrode.Then,PbS QDs were modified to the surface of TiO₂ NPs/ITO electrode by SILAR cycle method to prepare PbS QDs/TiO₂ NPs/ITO electrode.Due to the combination of large band gap TiO₂ NPs and narrow band gap PbS QDs,the photocurrent of the detection system is effectively enhanced.At 470 nm visible light,PbS QDs are excited to generate electrons and holes.The electrons are transferred to the TiO₂ NPs and the holes and the holes are trapped by GSH in the solution.Then GSH is oxidized to GSSH,which effectively avoids the recombination of electrons and holes of PbS QDs,thus improving the photoelectrocatalytic performance of the sensor.The sensor has a highly sensitive detection of GSH.The detection range is0.06¹ mmol/L and the limit of detection?LOD?is 4.6?10^-33 mmol/L?S/N=3?.?2?A novel PFOA photoelectrochemical sensor based on CdS QDs/TiO₂ NPsThe study found that perfluorooctanoic acid?PFOA?is toxic and carcinogenic to animals and humans,and PFOA has been detected in various water sources,soils,air,and organisms.Therefore,the establishment of PFOA accurate analysis method is significance for environmental detection and life and health.The cadmium sulfide quantum dots?CdS QDs?were successfully prepared by using thioglycolic acid?TGA?as a stabilizer.CdS QDs were modified onto the surface of TiO₂/ITO electrode by layer-by-layer self-assembly technique to prepare CdS QDs/TiO₂ NPs/ITO electrodes for the detection of PFOA.In this sensor,PFOA is adsorbed to the electrode surface by the carboxylate on the surface of the CdS QDs interacting with protons in the PFOA.Due to the accumulation of PFOA on the electrode surface,the diffusion of the electron donor to the electrode surface is hindered,so that the photocurrent is lowered.The prepared sensor has high sensitivity and high selectivity to PFOA,the linear range is 0.05⁰.7mmol/L,the LOD is 9.6?10^-33 mmol/L,and the average recovery is 98.2¹02.2%.?3?H₂O₂ photoelectrochemical sensor based on CdS QDs/Au NPs/TiO₂ NPsHydrogen peroxide?H₂O₂?plays an important role in chemical industry,environmental detection and biological processes,and it is associated with a variety of diseases.In this experiment,firstly,CdS QDs/Au NPs/TiO₂ NPs composite materials were successfully prepared by high-temperature calcination and layer upon layer self-assembly,as photoelectric active materials of PEC sensors.Then,HRP was modified to the surface of the CdS QDs/Au NPs/TiO₂ NPs/ITO electrode by coupling reaction to prepare HRP/CdS QDs/Au NPs/TiO₂ NPs/ITO electrode,which has good photoelectric properties.When HRP/CdS QDs/Au NPs/TiO₂ NPs/ITO electrodes are placed in PBS buffer?pH=7.4?containing 4-chloro-1-naphthol?4-CN?and H₂O₂,H₂O₂ was catalytically oxidized by HRP.At the same time,4-CN will be converted into insoluble and insulating 4-chloro-1-naphthalenone and deposited on the surface of the electrode to form an insulating layer,which hinders the diffusion of the electron donor ascorbic acid?AA?to the electrode surface,resulting in photocurrent reduce.The prepared sensor has high sensitivity and high selectivity to H₂O₂,the linear range is 0.2¹ mmol/L,the LOD is 53?10^-33 mmol/L,and the average recovery is98.75¹01.3%.