Construction And Application Of Salicylic Acid Molecularly Imprinted Photoelectrochemical Sensor Based On Organic-Inorganic Hybrid Perovskite

Photoelectrochemical(PEC)sensor,evolved from solar cells,is a novel analytical method with high efficiency and excellent detection performance.With the development of the Materials,new optoelectronic active species are the state-of-the art.The photo-active electrodes with high photoelectrical conversion efficiency would effectively improve the sensitivity of the PEC sensor,which has become the focus of PEC sensor development.Organic-inorganic hybrid perovskites have excellent photoelectrical performance and are widely used in various fields such as solar cells and photocatalysis.In this thesis,the organic-inorganic hybrid perovskite was used as the photosensitive material,which was modified by different methods to significantly improve its stability and photoelectrochemical response ability.Based on these,combined with molecularly imprinted polymer(MIP)recognition elements,the PEC sensor was constructed for the detection of salicylic acid(SA).The major contents were described as follows:Part One Dual functional molecular imprinted polymer-modified organometal lead halide perovskite:synthesis and application for photoelectrochemical sensing of salicylic acidThe CH3NH3PbI3 film was successfully formed on indium tin oxide glass(ITO)through one-step method.The MIP polymer was imprinted on the surface of CH3NH3PbI3/ITO by thermally initiated free radical polymerization,using salicylic acid as the template molecule.The as-obtained MIP/CH3NH3PbI3/ITO electrode was characterized by Scanning Electron Microscope(SEM),X-ray Diffraction(XRD),Photoluminescence(PL)and other techniques,indicating that both stability and electron-hole separation efficiency of CH3NH3PbI3 were increased by employing MIP.Thanks to the excellent photoelectrical performance of CH3NH3PbI3 and the high selectivity of MIP,the linear range of the PEC sensor for the detection of salicylic acid was 7.0×10-13-1.0×10-8 mol·L-1 with the limit of detection was 1.95×10-13 mol·L-1.The PEC sensor,with numerous amounts of recognition sites to salicylic acid,exhibited desirable performance in terms of good sensitivity,selectivity,stability,and feasibility for real sample analysis.This work not only featured the use of MIP/CH3NH3PbI3 for PEC detection of SA,but also provided a new horizon for the design and implementation of functional polymers/perovskite materials in the field of PEC sensors.Part Two Molecularly imprinted polymers and PEG double engineered perovskite:an efficient platform for constructing aqueous solution feasible photoelectrochemical sensorIn this chapter,amphiphilic polymer polyethylene glycol(PEG)was used to modify CH3NH3Pbl3,which endowed CH3NH3PbI3 moisture resistance.MIP-PEG/CH3NH3PbI3/ITO electrode was synthesized by anchoring a selective MIP for salicylic acid on the PEG modified CH3NH3PbI3 through a facile UV-polymerization process.Through various characterization techniques,it was proved that MIP and PEG formed the copolymer,which was modified on CH3NH3PbI3 to improve its stability and photoelectrical response capability.Under optimal conditions,salicylic acid was detected by monitoring the changes of the photocurrent signals of the PEC sensor resulting from the reaction between salicylic acid and MIP.The liner range of the as-fabricated PEC sensor was 1.0×10-15-7.0×10-11 mol·L-1 with the detection limit of 2.71×10-16 mol·L-1.The MIP-PEG/CH3NH3PbI3 PEC sensor has the advantages such as sensitivity,selectivity,stability and feasibility for real samples.Part Three Construction and application of salicylic acid molecularly imprinted photoelectrochemical sensor based on CH3NH3PbI3/TpPa-1-COFIn this chapter,a two-dimensional covalent organic framework(COF)TpPa-1 based on Schiff-base condensation was applied to form CH3NH3PbI3/TpPa-1-COF precursor solution.This precursor solution was modified on an indium tin oxide coated(ITO)glass.Using the salicylic acid as the template,the MIP was synthesized by UV-light initiation.The MIP/CH3NH3PbI3/TpPa-1-COF/ITO photoactive electrode was prepared and PEC sensor was constructed for the detection of salicylic acid.The prepared electrodes and PEC sensor were characterized by various techniques.The results showed that the photoelectrical response and stability of CH3NH3PbI3 was significantly enhanced due to the high specific surface area and high stability of TpPa-1,achieving the highly sensitive detection of SA eventually.The linear range was 1.0×10-15-1.5×10-11 mol·L-1 with the detection limit of 2.31×10-16 mol·L-1.The PEC sensor based on MIP/CH3NH3PbI3/TpPa-1-COF/ITO has the characters of high sensitivity,high selectivity,and high stability with fast speed.It has been successfully used in the real sample analysis.