Synthesis Of Porous Nickel Oxide Nanomaterials And Its Gas Sensing Studies

Nickel oxide(NiO)is a typical p-type metal oxide semiconductor sensing material.For a long time,how to effectively improve its sensing performance is the focus of the research.The main factors that affect the sensing properties are the structure and composition of the nanomaterials.Three dimensionally ordered macroporous(3DOM)structure can providemore active sites due to its large surface area,high porosity and long-range ordered periodic structure.Tetravalent tin(Sn)doping into the NiO lattice will introduce free electrons.Semiconductor composite will form p-n heterojunction,changing the concentration and carrier mobility of the materials,which is conducive to the formation of more chemisorbed oxygen.In this work,3DOM NiO,Sn-doped 3DOM NiO and 3DOM NiO-NiFe2O4 nanomaterials have been prepared by using the colloidal crystal template method.The effects of the structure and composition of the nanomaterials on the gas-sensing properties have been studied deeply.The details are as follows:1.A series of Sn-doped 3DOM NiO with different doping ratios have been prepared and their gas-sensing properties have been studied.Appropriate Sn doping content can effectively improve the gas response,stability and selectivity of 3DOM NiO to formaldehyde.The 3DOM NiO/10%Sn has a gas response of 145 to 100 ppm formaldehyde at 225 °C,which is about 85 times higher than that of pure 3DOM NiO.Gas sensing mechanism studies have shown that 3DOM NiO/10%Sn has large surface area and high porosity.Sn doping provides more free electrons for the NiO nanomaterials through the electron compensation mechanism,reducing the carrier(hole)concentration of the materials,and increasing the chemisorbed oxygen on the surface of the materials,which will enhance the gas-sensing properties to formaldehyde.High-performance NiO gas-sensing materials provide theoretical support for the practical application of sensing elements.2.The 3DOM NiO-NiFe2O4 nanocomposites have been prepared and their gas-sensing properties have been studied.The response of the nanocomposites to 100 ppm acetone was 58.7 at 260 °C.The analysis results shown that the role of semiconductor composite is to form p-n heterojunction,increasing the carrier mobility of the nanocomposite,producing more chemisorbed oxygen,thereby improving gas sensitivity.