Preparation And Properties Of Porous Single-Crystalline ZnO Nanosheets Gas Sensors

Zinc oxide(ZnO)is a kind of n-type semiconductor material with a wide band gap(3.4 eV).It is widely used in gas sensors,optoelectronic devices and photocatalysis because of its low cost and stable chemical properties.However,the application of ZnO gas sensors still have the disadvantages of low sensitivity,high working temperature,poor selectivity and poor stability,which greatly limit its application in the construction of national economy.In this paper,three-dimensional porous single-crystalline ZnO nanosheets were synthesized and the effect of gold nanoparticles(Au NPs)on the gas sensing has been studied,the performance of the UV-activated single ZnO nanosheet gas sensor has been investigated The main contents were as follows:The hierarchical porous single-crystalline ZnO nanosheets(HPSCZNs)were synthesized through a one-pot wet-chemical method followed by an annealing treatment.Polyethyleneimine(PEI)was used to modify the surface of the HPSCZNs,and then the PEI-modified samples were mixed with Au NPs sol solution.Electrostatic interactions drive Au NPs loading onto the surface of the HPSCZNs.The properties of the porous single-crystalline of the material have been confirmed by characterization.The effects of the formation mechanism,working temperature and gold content on the sensor's performance have been investigated,and the optimal value has been selected.Finally the gas sensing mechanism has been discussed in depth.It was reported that the polycrystalline structure would lead to poor stability of gas sensors,and the gas sensors were mostly with higher operating temperature.In this paper,the PSCZNs was ultrasonically dispersed in ethanol and added to the Au interdigitated electrode.A single layer ZnO gas sensor was fabricated by depositing platinum(Pt)layer connected electrode with a focused ion beam double-beam system(FIB).Scanning electron microscopy(SEM)images showed the good condition of the single ZnO and the connectivity with the electrodes and the gas sensitivity of ethanol was explored.Finally,the mechanism of UV activated sensor was discussed in depth.