Photoelectric Properties And Biosensing Of Controllable Fabricated ZnO Microspheres

Whispering gallery mode?WGM?microcavity can reduce the optical loss,threshold and improve the quality factor through the inner wall total reflection of light,which makes WGM microcavity as a promising candidate for lasing,biological detection and quantum physics.In various WGM microcavites,the isotropic microsphere is more conducive to reducing the optical loss and improving the quality of microcavity.Due to its advantages such as the direct band gap,high exciton binding energy,high refractive index,rich morphology,simple preparation,and good biological compatibility,Zinc Oxide?ZnO?with symmetrical geometry can be used as a natural WGM microcavity that does not require an external gain medium.It is of a great significance on the research to study how to effectively synthesize ZnO microspheres with controllable morphology,crystallinity and surface roughness.In addition,it is also worthwhile to synthesize various ZnO composite microcavities to improve their performance and apply to different fields.With the development of plasmon photonics,the performance of surface plasmon-enhanced semiconductor materials has attracted widespread attention.The collective oscillation of free electrons from the metal surface caused by the incident light can make the light field energy highly localized on the surface,which exhibits strong near-field enhancement characteristics.By couplling efficiently with the evanescent wave propagating on the surface of the microcavity,it can be achieved that luminescence and absorption enhancement.The intrinsic luminescence efficiency and the light utilization of ZnO can be effectively improved by using this physical effect,which has great prospects for designing and constructing new optoelectronic devices and biosensors.This paper aims to realize the controllable synthesis of ZnO microstructures by hydrothermal method and laser ablation method.ZnO microspheres with different structures can be flexibly selected according to the applications.The microcavity is coupled with the surface plasmon,which can enhance the ultraviolet luminescence,photocatalytic property and surface Raman scattering of ZnO microcavity in the field of optoelectronic and biosensing.The main contents are listed as follows:1.Different ZnO structures were successfully prepared by hydrothermal method and laser ablation method.ZnO microspheres with different sizes and surface roughness were prepared by the synergistic action of C₆H₁₂N₄ and trisodium citrate.The internal structure of sphere can be adjusted by changing the aging time after hydrothermal reaction.The smooth ZnO sphere with high crystallinaty also could be prepared in one step by the instantaneous heating from pulsed laser.2.The metal plasma and graphene were decorated on the surface of smooth ZnO microspheres to enhance their ultraviolet luminescence.The WGM lasing of ZnO microspheres was significantly enhanced by using of the local surface plasmon resonance effect?LSPR?and electron transfer process from Au nanoparticles.The coverage of single-layer graphene on the surfaces of ZnO microspheres can lead to different photoluminescence,which further proved that the graphene surface plasmon formed an effective coupling with the ZnO excitons.3.The ZnO/metal composite can achieve efficient photocatalysis by expanding the absorption range and promoting the separation and migration of electron holes.The hollow ZnO/Ag microspheres fabricated by photochemical deposition showed high degradation rate for methylene blue,methyl orange,phenol red and Rhodamine 6G under different light sources.Different Pt/ZnO/CdS spherical structures were constructed for the photocatalytic hydrogen production.And the hydrogen production efficiency could be greatly improved with the help of their morphologies.4.A Surface Enhanced Raman Scattering?SERS?substrate with recyclability,high stability and ultra-sensitive properties was constructed on the basis of porous ZnO/Ag microspheres and photocatalysis of semiconductor,and showed ultra-highly sensitive detection for Rhodamine 6G,phenol red,dopamine and glucose.In addition,the reactive oxygen species?ROS?and Zn²⁺released by ZnO made porous ZnO/Ag inhibit the growth of Escherichia coli?E.coli?,Staphylococcus aureus?E.aureus?and Enterococcus faecalis?E.faecalis?effectively.