Improve NiO Nanomaterials Toluene And Xylene Gas Sensing Properties By Semiconductor Composition And Doping

Nowadays, with rapid development of science and technology, people’s standard of livingincreases rapidly. At the same time, people draw due attention to all sorts of problems. Theproblem of air pollution becomes more and more serious. Combustible and explosive gases andpoisonous gases endanger people’s health all the time. Therefore, how to effectively monitor anddetect combustible and explosive gases and poisonous gases has become an important problem.Metal oxide semiconductor gas sensors have excellent performance and low cost. In this article,we choose nickel oxide semiconductor material as sensing material. However, pure metal oxidesemiconductor materials always show poor sensitivity and selectivity. Thus, we make somemodifications for nickel oxide semiconductor material to improve gas sensing properties.In this article, we take two methods to improve the gas-sensing properties of the nickeloxide materials. Firstly, we use semiconductor composition technology to enhance the gassensing performance of the nickel oxide. Secondly, we use doping method to enhance the gassensing properties of NiO materials. The detail methods are shown as follows.The NiO materials were prepared through hydrothermal method. The NiO materials werecharacterized by XRD, SEM and BET. The gas sensing properties of NiO materials were alsoinvestigated systematically. The results showed that the hollow structure NiO material exhibitedthe excellent performance gas sensing to toluene and xylene. NiO hollow structure ofnanomaterials based gas sensor is the highest response for toluene, which illustrate the NiOhollow structure nanometer materials have the potential to become excellent toluene, xylene gassensor.We use semiconductor composition technology to enhance the gas sensing performance ofthe nickel oxide. The Fe3O4-NiO core-shell composite materials were synthesized byhydrothermal method. The composition of Fe3O4can improve the toluene and xylene sensingproperties of NiO gas sensor, especially the response and selectivity. At the optimum operating temperature of Fe3O4-NiO composite materials, the response to100ppm toluene of Fe3O4-NiOcomposite materials was3times lager than that of NiO materials. The selectivity performancewas also enhanced after the composition of Fe3O4. The enhancement gas sensing performance ofFe3O4-NiO composite materials was caused by the change of heterojunction barrier in targetedgases and air.To solve the poor selectivity of NiO materials, we use the doping method to improve the gassensing properties of NiO materials. The Cr doped NiO materials were obtained by hydrothermalmethod. The optimum amount of Cr was investigated and the result showed that the2at%Crdoped NiO showed the best gas sensing prosperities to xylene. Two factors may account for theenhancement of Cr doped NiO materials. The first one is that the doping of Cr can increase thesurface oxygen vacancy, which enhanced the ability of oxidizing at the surface. Besides, thecatalytic effect of Cr or Cr2O3to methyl is another key factor for the enhanced gas sensingproperties of nickel oxide.