Graphene In-situ Synchrotron Characterization Platform And Its Applications

Graphene is the name given to a flat monolayer of carbon atoms tightly packed into a two-dimensional(2D)honeycomb lattice,combines extreme mechanical strength,exceptionally high electronic and thermal conductivities,impermeability to gases,as well as many other supreme properties,all of which justify its nickname of a miracle “omnipotent material”.Recent years have witnessed the progresses of the synthesis of large area graphene with high crystallinity and controllable layers by chemical vapor deposition,significantly advanced its applications in nano-electronic devices,biomedicine,solar cells,supercapacitors,Li-ion battery and many others.However,until now,the controllable graphene growth and its structural refinement through chemical vapor deposition are still mainly on the basis of “trial-and-error approach”,with limited researches focus on the in-situ thermodynamics,kinetics,growth mechanism(s),real-time structure regulations and the structure-performance relationship in graphene applications.Those researches are blocked by the lack of insitu experimental setup and corresponding time-resolved characterization techniques.On the other hand,the high brightness,tunable energy,coherence,high collimation,large equipment integrated space of synchrotron radiation can provide multiple technologies that enable the real-time dynamics study of materials.Thus,here,based on the hard X-ray diffraction and absorption spectrum beamlines in Shanghai Synchrotron Radiation Facility,we construct a universal in-situ chemical vapor deposition platform,battery cells and moisture cells,toward the in-situ study of graphene growth,refinement and electrochemical application.The main studies include the following aspects:1)Using the home-made chemical vapor deposition(CVD)chamber,we demonstrated the direct growth of graphene on a single-crystal silicon surface.In-plane propagation,edge-propagation,and core-propagation processes were proposed to evaluate the sequentially changing graphene domains at serial growth temperatures.A better understanding of the direct nucleation and growth mechanisms may enable the synthesis of large area and layer-controlled,highquality graphene on single crystal silicon substrates.2)We developed a sub-second time-resolved two-dimensional X-ray diffraction grazing-incidence(2D-GIXRD)platform combination with in-situ CVD chamber,which can track the continuous evolution of the interlayer spacing and related structural parameters during the growth of graphene and the following protonation process.Using this technique,we demonstrated that thermal protons can transport through multilayer graphene on nickel foil at 900 °C.In comparison,under the same conditions,the multilayer graphenes are impermeable to argon,nitrogen,helium,and their derived ions.Complementary in situ transport measurements further verify the penetration phenomenon at high temperature.3)3-dimensional skeleton composite materials consisting of a core-shell amorphous porous carbon/multilayer graphene are synthesized by chemical vapor deposition on Ni foam using a facile one-step growth method.The data suggest that these composites have not only outstanding electrical and mechanical properties of the multilayer graphene but also the mesoporous characteristics of the amorphous carbon.The carbon composites exhibit ultralow density and high conductivity.In-situ synchrotron radiation characterizations reveal the property-structure relationships of graphene composites,which further demonstrate its superior electrochemical performance and the potential to explore practical applications.