Research On Preparation And Gas Sensitivity Of P-type Co₃O₄,NiO Nanomaterials

With the increasing emphasis on environmental issues,the gas sensor as a convenient detection method has become more widespread.The effective detection of toxic gases is of great significance to ensure the environment and healthy life of human beings.Metal oxide gas sensors have become a hot topic in the field of gas sensitivity due to their low cost,simple preparation process,and portability.With the increasing demand of gas environment monitoring,the requirements of sensors are getting higher and higher.Researchers are committed to improving the comprehensive performance of metal oxide gas sensors.Two of the most commonly used methods are the morphology control of sensitive materials and the use of additives.In this paper,p-type semiconductor Co3O4 and NiO are used as sensitive materials to improve the sensitive performance of the gas sensor by adjusting the morphology of the material,using metal doping,and surface modification,and the mechanism of enhancing the sensitive performance of the sensor is discussed in detail:1.In this study,we used ZIF-67 as the reactant to prepare cobalt-based nanosheet structure.In order to compare the influence of morphology on gas sensing performance,cobalt-based nanosheet was converted into porous Co3O4 nanosheets by regulating the calcination temperature to obtain small nanopartical size and continuous phase.The experimental results show that the porous material can effectively increase the amount of load on gas molecules,and the sensitivity of mesoporous Co3O4 nanosheets are outstanding after the heat treatment at 350?.The response value to 100 ppm acetone was 24.8,and the response/recovery time was 15.2/14.8 s.Also,the stability of the material could reach 86.4%of the initial response value to 100 ppm acetone after 35 days,and it had a low cross-reaction to other gases.The excellent performance of porous Co3O4 nanosheets is attributed to ultrathin and porous structure,which provides smooth gas transport channels,enhances the adsorption of gas molecules,and provides rich catalytic sites.2.In this paper,porous flower-like NiO nanomaterials doped In were successfully prepared by simple hydrothermal and calcining method using ethylene glycol as structural guide.In order to further improve gas sensitivity,Ag nanoparticles were loaded on the surface of 3 at%In-doped NiO nanosheets(AgNPs/3 at%In-NiO)and the gas sensitivity of methanol was prepared.The short response time of NiO nanomaterials to 100 ppm methanol was 6.3 s,but the selectivity was not obvious,the response to 100 ppm methanol was 2.16.After doping 3 at%of In,the sensitivity to 100 ppm methanol reached 6.93,which improved the selectivity of methanol.Further loading of Ag nanoparticles,the sensitivity of AgNPs/3 at%In-NiO to 100 ppm methanol was 16.3,which greatly improved the sensitivity of methanol,and the performance was 8 times than that of pure NiO nanomaterials.The material improves the selectivity and sensitivity of methanol,indicating that the noble metal catalysis is the main reason to improve the methanol sensing performance.In summary,we effectively improved the sensitivity of gas detection by adjusting the morphology of Co3O4 and applying additives to NiO nanomaterials,which provided a new idea for the manufacture of gas sensors.