Study On The Performance Control Of TiO₂ Composite Electrode And Its Application In Photoelectrochemical Sensing

Nucleic acid,as a kind of substance carrying biological genetic information,is an important marker in clinical detection.PEC sensing successfully realizes the separation of signal excitation and detection,has the advantages of high signal-to-noise ratio,and can realize the highly sensitive analysis of nucleic acid targets.As a key part of PEC sensing process,the electrode active material often determines the performance of the sensor.TiO₂ has been widely used in the field of photoelectric biosensing due to its excellent chemical stability,photocatalytic activity and biocompatibility.However,the electron transfer between TiO₂ and electrode is very limited due to the poor conductivity of TiO₂.At the same time,the photochemical activity of TiO₂ electrode is affected by the poor visible light absorption and the rapid recombination of photogenerated charge.In this paper,through the means of materials science,the performance of TiO₂nanomaterials is regulated,effectively increasing the life and density of photogenerated carriers of TiO₂ materials.We use the modified electrode to realize the efficient detection of the target object.This research is expected to provide design ideas and experience for the development of a new generation of nucleic acid sensor electrode.Specific contents include:（1）In Chapter 2,layered Ti₃C₂T_x material was prepared successfully,and（001）exposed TiO₂ nanosheets were grown in situ on Ti₃C₂T_x material.After performance adjustment,the carrier lifetime of the electrode reaches about 2 ns and the density reaches 9.86×10¹⁸.The electrode can detect the target in the linear range of 1 p M-10n M,and the calculated detection limit is 0.3 p M.（2）In Chapter 3,an array of（001）exposed TiO₂ nanosheets was in-situ grown on the FTO substrate and loaded with In₂S₃ on the electrode surface.A type II heterojunction structure is established between In₂S₃ and TiO₂ to improve the charge separation ability of the electrode.After the modification of In₂S₃,the carrier lifetime of the electrode reaches about 2.96 ns,the density reaches 6.81×10¹⁹,and the detection performance is good in the range of 0.1 p M to 10 n M,and the detection limit is 0.07p M.（3）In Chapter 4,zero-dimensional Ti₃C₂T_x quantum dots are synthesized and loaded onto TiO₂ electrodes exposed on the（001）crystal surface.Ti₃C₂T_x quantum dots form an intramolecular type II heterostructure with TiO₂.After modification,the carrier lifetime reaches about 3.73 ns,and the density reaches 8.18×10¹⁹.Stable,sensitive and selective detection of micro RNA-155 can be achieved in the range of 0.1 p M to 10 n M.The detection limit was 0.025 p M.（4）In Chapter 5,the electrode structure is further designed,and the dendritic TiO₂nanorods array is used as the photoelectric detection electrode.The carrier lifetime of the electrode is about 3.97 ns,the density is 1.32×10²⁰,and the reliable and efficient detection of micro RNA-155 is realized.The detection range is 1 f M-10 n M,and the detection limit is 0.3 f M.（5）In Chapter 6,the dendritic RA-TiO₂ phase structure electrode is prepared.Rutile and anatase TiO₂ can form a structure similar to type II heterojunction and form a self-built electric field at the interface of the two electrodes.After modification,the carrier lifetime of the electrode can reach about 8.02 ns,and the density can reach 1.63×10²⁰.In the linear range of 1 f M～10 n M,high sensitivity for stable analysis of target DNA can be realized.The detection limit was 0.23 fM.