Preparation Of CuO Nanomaterials Doping Different Metal Ions And Study On Their Properties Of Gas Sensing

Metal oxide（MOS）gas sensors are a promising portable gas detection device due to their low cost,simple production and small size.The performance of such sensors strongly depends on the properties of the material,such as morphology,structure and doping.In this study,we report the effects of different types of metal ion doping on the sensors of copper oxide（CuO）nanomaterials for various gases.Pure CuO and CuO nanomaterials doped with different metal ions（M-CuO）were prepared using a simple hydrothermal method.To understand the effect of different metal ion doping in CuO,different molar percentages of metal ions were doped with CuO.The structural morphology and crystalline phase elemental energies of the synthesised nanomaterials were investigated using XRD,SEM,BET,XPS and Raman characterisation instruments.Thin film gas-sensitive sensors were also prepared for all samples and subjected to different gases for detection.A systematic comparative study reveals the enhanced gas sensing performance of different metal ion doped CuO sensors for isopropanol gas.The main studies are as follows:（1）Ni-doped CuO micro-and nano-graded structures were successfully prepared by a low-temperature hydrothermal method,and the morphology and structure of the Ni-doped CuO mesoporous microspheres were assembled from many nanosheets according to SEM analysis.XRD and XPS results showed that the element Ni was present in the+2 valence form and successfully replaced Cu in the CuO lattice.The doping of Ni plays an important role in improving the sensing performance of isopropanol The doping of Ni plays an important role in improving the sensing performance of the gas.The results of the gas sensing tests show that the optimum Ni doping concentration is 3%and that the response value for 100 ppm of isopropanol gas（3.7）is 2.1 times higher than that of a pure copper oxide gas sensor.The sensitivity of the Ni-doped CuO microspheres is linear with gas concentration in the range of 1 ppm to 100 ppm,even at low concentrations（1 ppm）with a response of 1.3.The 3%Ni-doped CuO microspheres have a larger specific surface area（32.169 m²/g）compared to pure CuO,resulting in better gas sensitivity.The improved sensitivity of the Ni-doped CuO microspheres is attributed to the higher defect content of the sender and the larger specific surface area.（2）Mn-doped CuO nanoflower spheres with different concentrations were synthesized by a low-temperature hydrothermal method.The prepared samples were characterised by XRD,SEM,TEM and XPS.The results showed that the material was a spherical micro-nano-graded structure with porous CuO nanosheets and the diameter of the nanoflower spheres ranged from 4-10μm.The CuO-1%Mn nanoflower spheres showed an excellent linear response to 1 ppm-100 ppm of isopropanol at an optimum working temperature of 235℃,and the response to isopropanol remained stable for 31days.1%Mn nanoflower spheres showed a high selectivity for isopropanol and the response to isopropanol gas was significantly higher than that of other VOCs gases.Analyzing its gas-sensitive mechanism,the doped Mn ions would replace the Cu sites,creating more defects and providing more active sites for the adsorption of isopropanols.And due to the spillover effect,thermally excited electrons will migrate to the surface of Mn ions,thus improving the separation efficiency of hole electron pairs in CuO and expanding the range of hole accumulation layers.The adsorbed O₂molecules are more readily bound to the electrons,forming more oxygen anions on the surface of the Mn ions.As a result,more isopropanol molecules can be oxidised on the Mn-doped CuO nanoflower spheres surface.In addition,the CuO-1%Mn nanoflower spheres have a larger specific surface area（33.079 m²/g）and more pores,therefore,the CuO-1%Mn nanoflower spheres have superior isopropanol sensing performance than pure CuO.Fig.[57]Table[7]Ref.[114]...