Preparation Of Heteroatom Doped Two-dimensional Energy Materials Through Low-temperature Plasma Route And The Research Of In-situ AFM In Two-dimensional Materials Characterization

Two-dimensional materials represented by graphene have shown a good application prospect in the fields of energy storage and transformation,which due to their special physical and chemical properties.As the most common modification method of two-dimensional materials,heteroatom doping was widely used in various two dimenisonal materials to improve their N or P type conductive properties and adjust their electrochemical activities.The preparation of such high-activity heteroatom doped two dimenisonal materials through a facile and efficient way is one of the most important research directions in the field of energy related materials.However,traditional preparation method for heteroatom doped materials always shows the disadvantages of high energy consumption and environmentally harmfully,such as solvent thermal method and high temperature treatment,which more or less unable to meet the urgent needs of the society.Based on the above issues,this thesis introduced the preparation of heteroatom doped reduced graphene oxide and graphite phase carbon nirtride materials by using high-efficiency dielectric barrier discharge plasma technology.Great electrochemical and photocatalysis performance and reaction mechanism of the as-prepared materials were also confirmed and explored in this work,respectively.Moreover,this thesis took two-dimensional Co?OH?₂ nano-sheet as the model material,preliminarily explored the application of in situ atomic force microscope?AFM?technology in the characterization of two-dimensional materials,which in view of the deficiency of mechanism analysis of two-dimensional energy materials in electrochemical application.The detailed research main contents are as follows:?1?Boron doped reduced graphene oxide?B-rGO?was successfully prepared by using DBD plasma technology.The boron doped material with a doping content of 1.4%could be obtained only in about 3 min by this plasma process route,and the as-prepared B-rGO material exhibits great capacitance ability of 446.24 F g^-1 at the current density of0.5 A g^-1.What is more,the suggested low temperature plasma method has the advantages of high efficiency,environmentally friendly and easy for mass preparation.This study provides a new sight for the efficient preparation of heteroatom doped two-dimensional materials.?2?rGO/g-C₃N₄ and B-rGO/g-C₃N₄ composites for photocatalytic degradation were synthesized by using DBD plasma technology.XPS and FTIR results confirms the formation of C-O-C covalent bonds between rGO and g-C₃N₄ structure,and this covalent bonding ability could be enhanced by boron doping modification of g-C₃N₄.Moreover,the optical and electrical characterization demonstrated that the enhanced C-O-C covalent bonding could further improve the separation of the photo-generated chargers and narrow the bandgap of the nanocomposites.Photocatalytic degradation experiments confirmed the photocatalytic degradation efficiency of B-rGO/g-C₃N₄composites was 50%higher than rGO/g-C₃N₄ composites?under a same optimized rGO addition level?.What is more,the photocatalytic degradation mechanism of as-prepared composites was studied in detail:organic pollutants were mainly oxidized to small molecules by photo-generated holes and·O^2-free radicals.?3?The study on the mechanism investigation of?-Co?OH?₂ two dimensional nanosheet materials during electrochemical application was conducted this thesis.In-situ electrochemical AFM was utilized to study the dynamics mechanism of Co?OH?₂nanosheet.The in-situ AFM measurement clarified that in the potential range which only one redox reaction?Co?OH?+OH?CoOOH+H O+?occurred,the basic structure size of Co?OH?₂ sheet enlarged with the cyclic voltammetry?CV?cycle number increased.The in-situ AFM measurement in single CV cycle confirmed that the effects of structure expansion always exists,the overall trend is independent from the redox reaction.The dynamics mechanism of Co?OH?₂ nanosheet was proposed based on ex-situ SEM,XRD and XPS results and in-situ AFM measurement of Co?OH?₂nanosheet:the structure expansion phenomenon can be explained by the effect of H₂O molecule insertion into the Co?OH?₂ crystal layer and dissolution/re-deposition of Co?OH?₂.Moreover,the stability performance of hexagon Co?OH?₂ nanosheet was directly influenced by the structure morphology.This research results provide a theoretical basis for the subsequent design and preparation of similar materials.