Study On Synergistic Sensitization Effect Of Ag-M Bimetallic Catalyst In ZnO-Based Gas Sensor

ZnO nanomaterials have many excellent physical properties and are widely used in sensors.However,the intrinsic semiconductor ZnO gas sensor is still unsatisfactory in terms of sensitivity and selectivity which can be significantly improved by adding a precious metal.To avoid the problems of single-metal catalysts using Pd,Pt and other precious metal poisonous,may lose activity,and high cost,a second metal is added to the precious metal catalyst to form a bimetallic nanocrystalline catalyst with a synergistic sensitization effect,providing a new solution for improving gas sensor performance.The results in this article are as follows:(1)A micro-electromechanical system(MEMS)process was used to manufacture an indirectly heated miniature sensor chip.One-dimensional ZnO nanowire material was grown on the sensor chip in situ,and a ZnO-based gas sensor was successfully manufactured.The experimental results showed that the detection limit of ZnO-based gas sensor for hydrogen was 10 ppm,and the detection limit for formaldehyde was 2 ppm.(2)A hydrogen sensor was successfully manufactured by synthesizing Pd-Ag bimetallic nanoparticle material using the hydrothermal method and loading it onto the surface of ZnO nanowire through inkjet printing technology.Compared with a single Pd or Ag nanoparticle catalyst,the catalytic activity of Pd-Ag bimetallic nanoparticle catalyst with synergistic sensitization effect on hydrogen was significantly improved,and the detection limit of hydrogen was 1 ppm.(3)Pentagonal Pt-Ag bimetallic core-shell structure nanomaterials were synthesized by the hydrothermal method and loaded onto the surface of ZnO nanowires by inkjet printing technology to successfully manufacture a formaldehyde gas sensor.Compared with a single Pt or Ag nanoparticle catalyst,the catalytic activity of pentagonal Pt-Ag bimetallic nanocrystals with synergistic sensitization effect on formaldehyde was significantly improved,and the detection limit of formaldehyde was 120 ppb.The online mass spectrometer test results show that HCHO molecules will be partially oxidized to HCOOH molecules at low temperature,and will be completely oxidized to CO2 molecules at high temperature.