In Situ Study Of Interaction Between Two-dimensional Nanomaterials And Gases

As the unique properties of two-dimensional (2D) nonmaterial spring up continually, theresearch of two dimensional nanomaterials moves towards increasing sophistication. Theinteraction of gas and two dimensional nanomaterials is widely applied in post-processing oftwo-dimensional nanomaterials, because it can boost the performance of two-dimensionalphotoelectric device. Besides, the interaction can change the conductive properties oftwo-dimensional nanomaterials, therefore, it has a potential application prospect in the field ofgas sensor.In this thesis, we systematically studied the interaction of graphene as well astwo-dimensional metal oxide with gas molecules by using the in-situ Raman spectroscopy andX-ray photoelectron spectroscopy method. We mainly discussed the impact of gas moleculeson structure and electrical properties of2D nanomaterials. Mainly including two aspects asfollowing:1、The experimental graphene was prepared by chemical vapor deposition. The graphenewas annealed in three kinds of different gases such as nitrogen、argon and oxygen, combinedwith in-situ Raman spectroscopy and Hot&Cold stage, during the annealing process, thein-situ Raman spectroscopy measurement of graphene was conducted. At the same time, weanalyzed the impacts of annealing effect in different gases atmosphere on Raman characteristicpeaks of graphene. Annealing process in different gases would result in changes of stress andappearance of disorder structure. Doping effect came into being during the process as well,because of the interfacial effect between graphene and substrate.2、The hydration tungsten trioxide nanoplates were prepared by hydrothermal method.H2O molecules in the hydration WO3nanoplates can be annealed out and its phase will changefrom orthorhombic to monoclinic after annealing. The hydrogen response of hydration WO3nanoplates before and after annealing is investigated and the interaction mechanism is revealedusing in-situ Raman spectroscopy and quasi-situ X-ray photoelectron spectroscopy. We find thatstructural water molecules form in the nanoplate during its interaction with hydrogen. However,the generation of oxygen vacancy is not observed. The reduction of W6+to W5+and coloration phenomenon was due to structural displacement and electron transfer during the interaction,and that’s why the electrical conductivity increased.