The Application Of Gold Nanoparticle Sensitized Semiconductor Tin Dioxide And New Photoelectric Material Perovskite In Photoelectrochemical Sensing Analysis

Photoelectrochemical sensor operates in a similar principle to that of solar cell,and is an expanded application of photoelectrochemistry in the field of analytical chemistry detection.Since photoelectrochemical device use light as a signal input and current as a signal output,they can effectively avoid the background interference of signal input,thus it is an analysis method with high potential.Photoelectrochemical devices have the advantages of simple construction,low cost,easy to realize miniaturization,high throughput detection,low background response and high sensitivity.So they have attracted significant interest from researchers.Based on different photoelectric conversion materials,photoelectric chemical sensors generally can be divided into two categories:one is the photoelectrochemical sensor based on the inorganic semiconductor nanomaterials,and the other is optoelectronic chemical sensors based on the dye sensitized semiconductors.Out of the many semiconductor materials,SnO₂ is the optimal photoelectrochemical substrate material,because of its high thermal and chemical stability,low cost,low toxicity,high electron mobility.The electron mobility of nanoscale SnO₂ is as high as about 250 cm² v^-1s^-1,much higher than that of nanoscale TiO₂ anode optical materials(electron mobility about 1cm²v^-1s^-1).As N-type wide band gap semiconductor?band gap about 3.6 eV?,SnO₂has strong absorption for UV light,and visible light utilization of SnO₂ is not very high.Besides,after the light excites,electron/hole of SnO₂ semiconductor easily recombine,leading to low photoelectric response and poor sensitivity.Therefore,developing stable photoelectrochemical material with high utilization ratio of visible light is a hot research area for photoelectric chemical sensors.This work started from improving the semiconductor nanoscale SnO₂ photoelectric conversion rate and developing new photoelectric materials,constructed optical chemical sensors with high sensitivity,more stability and specificity,realized the detection of small molecular compounds and endocrine disruptors.The specific research contents are as the following:On the ITO glass electrode,ITO/SnO₂ electrode was prepared with the method of spin coating and sintering,then it was decorated with gold with a facile spraying method.The thickness of the decorated gold nanoparticles can be controlled through the time of the spraying time.This process is quite convenient.By using the preparation of ITO/SnO₂/Au electrode combined with optical signal molecules Ru?bpy?₃²⁺which can detect bisphenol A?BPA?,the linear range is 10_<sup><sup>-910^-5?M,the minimum detectable concentration reaches 1 fM,satisfying the requirement of national standard.Thus,this method has high potential for detection of endocrine disruptors.In recent years,inorganic-organic hybrid perovskites,represented by methylamine lead iodine compounds?CH₃NH₃PbI₃?,have became"star"materials in the field of photovoltaic materials,due to its strong absorption,high mobility and controllable band gap.Therefore,in this work,we introduced the organic-inorganic hybrid perovskite materials as a photosensitive layer and induction layer by one step synthesis method,and applied this system in the qualitative detection of hemin.This method opens the door to constructing sensors based on perovskite materials.In the second work,although the ITO/SnO₂/CH₃NH₃PbI₃ electrode has a low cost for preparation and good photoelectric effect,its poor stability,easy degradation in electrolyte solution,with a stability time of 120 s,make it incapable of quantitative detection for a long time.Thus,seeking for a way to improve the stability of the photoelectric detection system based on perovskite is necessary.In this work,we adopt electrospinning method to prepare porous SnO₂"cotton aggregate"structure,then rapidly soaked the perovskite precursors,allowing them to be immersed in SnO₂"cotton aggregate".After calcination,perovskite was trapped in the interior of the SnO₂"cotton aggregate".The results show that this method can improve the stability of the system.The detection time was improved to 2500 s,and this system can realize quantitative detection for Hemin.The results of this study show that the sensor based on Au-SnO₂ composite nanomaterials has high stability,high sensitivity and successfully solved the problem of low visible region absorption response and low photoelectric sensitivity for SnO₂;Organic-inorganic hybrid perovskite materials having high visible light absorption rate as optical sensitization layer and construction of photoelectric detection system greatly enriched the diversity of photoelectrochemical detection system.