Preparation Of NiO-based Composite Nanofibers And Their Acetone Gas-sensing Properties

Construction of high-performance gas sensors based on p-type metal oxides has always been a hot and difficult topic in the field of gas sensing.Therefore,in this work,with the objective of improving the sensing properties of p-type NiO,modifications of NiO have been done by construction of heterojunctions and noble metal decoration.A series of Nb2O5-NiO nanofibers and Rh-NiO composite nanofibers with various molar ratios were fabricated by a facile electrospinning technique.The effects of Nb2O5 and Rh contents on surface area,oxygen species absorbing capability,as well as acetone sensing properties of NiO nanofibers were systematically investigated,which provide experimental and theoretical reference for the development of high performance NiO based gas sensor.The specific results are as follows:(1)Nb2O5-NiO heterojunction nanofibers with different Nb/Ni molar ratios(0,6%,9%and 12%)were synthesized by a simple electrospinning approach,which effectively enhanced the specific surface area and oxygen adsorption capacity of material.Sensing results demonstrated that 9 mol%Nb2O5-NiO nanofiber sensor exhibited the highest sensing response.The response of 9 mol%Nb2O5-NiO sensor is 70.10 to 200 ppm acetone at the optimum work temperature 225 ?,which was 10 times higher than that of pure NiO nanofiber sensor.Moreover,the 9 mol%Nb2O5-NiO nanofibers also possessed excellent acetone selectivity.The enhanced acetone performances can mainly be attributed to the formation of p-n heterojunction between NiO and Nb2O5,which formed an internal electric field and accelerated the mobility of carriers in the material.Thus,electronic activity and the adsorbed oxygen content were increased,and the gas sensing properties were enhanced as well.(2)A series of porous Rh-NiO composite nanofibers with various molar ratios(Rh/Ni=3%,5%and 7%)were fabricated by a facile electrospinning technique.Sensing results demonstrated that the Rh-NiO sensor with an optimal Rh amount of 5 mol%exhibited the highest p-type response of 70.10 to 200 ppm acetone at 225?,which was 37.9 times higher than that of pure NiO nanofiber sensor.Moreover,the 5 mol%Rh-NiO nanofibers also possessed excellent acetone selectivity.The improved sensing response of Rh-NiO nanofibers was mainly attributed to the formation of ohmic contacts between Rh nanoparticles and NiO nanoparticles,facilitating the reduction of sensor resistance in air and the increase of chemisorbed oxygen capability.Chemical sensitization effect of Rh nanoparticles and increased BET surface area also contributed to the improved acetone response of Rh-NiO nanofibers.