| Since the discovery in 2004,Graphene has aroused the worldwide scientists extensitive attention and research owing to its novel optical performances and unique electrical properities.However,graphene is metal-like material,because its zero-band gap,which significantly restricts its electronic devices applications.Therefore,there is an urgent to find a new two-dimensional semiconductor with a band gap.Inorganic transition metal dichalcogenides(TMDS)represent a new series of two-dimensional materials possess not only graphene-like plane structure and mono-molecular thickness,but also direct band gaps.The innovative optoelectronic and catalytic properties suggest their great potentials for the applications of optoelectronics,energy storage and catalytics.This dissertation mainly focuses on the controllable and cost-effective preparation of high-quality TMDS nanosheets.By lithium ions intercalation method successfully obtained metallicity monolayered Mo S2 and WS2 nanosheets,the high concentration of active sites electrochemistry materials was obtained by physic method size reduction.The coductivity and the stability of Mo S2(WS2)nanosheets can be highly improved by controlling the 1T and 2H phases ratio on the nanosheets.Utilizing the high conductivity of graphene composites with monolayer Mo S2(WS2)nanosheets into three-dimensional porous aerogel materials,and application in lithium-ion battery anode materials showed the excellent electrochemistry performance.Detail contents of this paper are showed in the following:1)We prepared monolayered Mo S2(WS2)nanosheets materials by Lithium intercalated method,and successfully obtained monolayer Mo S2(WS2)nanosheets ratio more than 90%after optimizing the experiment technology.The monolayered Mo S2(WS2)own 2H and 1T hybridization phase in plane,and the first principle calculation further demonstrated that this special structure Mo S2materials own metal-like high conductivity and good room-temperature stability.By decreasing the traverse dimension of Mo S2(WS2)nanosheets using ultrasonication method,small-sized Mo S2(WS2)monolayer nanosheets and quantum dots can be obtained.The decrease of traverse size increases the concentration of active sites in edge and defect density of the nanosheets.2)We found by adjusting the annealing temperature,the ratio of in-plane 1T/2H phases of the Mo S2(WS2)nanosheets can be controlled to achieve high stability and conductivity for the nanosheet films.Combining with theoretical calculation,we designed the most stable and condctivitive 1T-2H Mo S2(WS2)nanosheets as electrode material for use in supercapacitor and hydrogen evolution reaction or other electrochemaical application and so on.3)We found the three-dimensional porous heterojunction aerogels compositing monolayered Mo S2(WS2)nanosheets and highly-conductive graphene not only own improved conductivity but also enhanced structural stability.By regulating the graphene/TDMS ratio,the morphology of the aerogel pore can be effectively controlled.Used as lithium battery electrode material,three-dimensional aerogel with 80 wt.%Mo S2 nanosheets achieved 1200 m Ah g-1 capacity,excellent cycling performance and stability at 100 m A g-1 current density.The Mo S2-graphene and WS2-graphene aerogels also showed superior capacitance,excellent rate property and battery cycle when used as anode materials in lithium ion battery. |
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