Preparation Of Porous ZnO Nanobelts Anchored With Noble Metal (Au,Pt) Nanoparticles And Application On Temperature-modulated Gas-sensing Behaviors To VOCs

Noble metal nanoparticles are widely used to improve the performance of gas sensors due to their strong catalytic activity.The modification of noble metals can catalyze the reduction of the reaction energy barrier of gas on the surface of oxide nano-sensitive materials and enhance their sensitivity,but most modification of noble metals all adopt post-chemical modification method,which easily causes noble metals to fall off and the size is not uniform,thus leading to the instability of the sensor.Based on this,we proposed an ion exchange strategy for the preparation of noble metal nanoparticles modified porous Zn O nanobelts.In addition,due to the solid cross-sensitivity of semiconductor metal oxides,it responds to a variety of gases and cannot achieve specific recognition of a certain gas.According to the dependence of semiconductor gas sensors on temperature,we adopt dynamic temperature modulated strategy studied the gas sensitivity characteristics of the sensor to different gases under different temperature conditions.The main research contents of this paper are as follows:（1）Au nanoparticle modified porous Zn O nanobelt enhances the gas sensitivity of benzene series.First,ethanol was used as a dispersant to uniformly disperse the Zn Se·0.5N₂H₄ precursor nanobelt,and after adding the HAu Cl₄ solution,the uniformly dispersed Au nanoparticle-modified porous Zn O nanobelt was obtained by the ion exchange-thermal oxidation method.The Au-modified porous Zn O nanoribbons are constructed into a sensor.First,the modification amount of different Au is optimized under static working temperature,and the best modification amount of Au is 1 at%Au/Zn O.The detection of benzene series by 1 at%Au/Zn O finally realizes high-sensitivity detection of benzene series with a detection limit of 1 ppm and a fast response recovery time.（2）The 1 at%Au/Zn O nanobelt realizes the specific recognition of benzene series under the control of dynamic working temperature.Dynamic temperature control changes the dynamic operating temperature by controlling the high and low voltages and the time corresponding to the high and low voltages loaded on both ends of the heating resistance wire.In the detection of benzene series,the system first explores its influence on the non-linear curve of benzene series by adjusting different frequencies under fixed voltage and duty cycle conditions.The results are at 0.02 Hz,0.03 Hz,and 0.04 Hz.Under all conditions,the specific recognition of benzene series can be realized;secondly,the influence of different duty ratios on the nonlinear curve of benzene series is explored by fixing the voltage and frequency,and the nonlinear curve of alcohol,ketone and aldehyde is compared;Finally,under the optimal voltage of 6.5 V,frequency of 0.02 Hz,and duty cycle of 30%,different concentrations of benzene series were tested,and it was concluded that benzene,toluene,m-xylene,and ethylbenzene under these conditions The non-linear curves of the benzene series are the same,but the non-linear curves between the benzene series are quite different,and the specific recognition of the benzene series is finally realized.（3）Pt modified porous Zn O nanobelts realize selective recognition of triethylamine.They were prepared by ion exchange-thermal oxidation method.The sensitivity test of triethylamine was conducted at static working temperature,and the optimal modification amount and optimal working temperature were determined;according to the gas sensitivity enhancement and the static temperature Dynamic temperature modulation strategy,select 1 at%Pt/Zn O nanobelt to test triethylamine,in the best temperature range,1 at%Pt/Zn O nanomaterials only achieve specific recognition for triethylamine,and for others A variety of gases cannot be specifically identified;in addition,we have explored the specific recognition ability of 1 at%Pt/Zn O for two-component gases.It can still be achieved when the concentration of triethylamine is maintained at 25 ppm and another gas is added.Specific recognition of triethylamine.