Application Of Graphene And MXene In Electromagnetic Wave Absorption And All-Solid-State Stretchable Micro-Supercapacitor Arrays

The prosperity and development of society is based on the human beings demand for the natural world,accompanied by serious electromagnetic pollution and energy crisis.Therefore,scientists from all over the world are committed to studying all kinds of functional materials to solve these problems related to the long-term development of mankind.Among them,two-dimensional materials(graphene,mxene,etc.)exhibit excellent chemical,physical and mechanical properties,and the use of these properties for technical applications(electromagnetic wave attenuation and supercapacitors,etc.)will effectively improve the embarrassing situation faced by human beings and further optimize the structural form of energy storage devices.Based on this,we have developed a graphene/flaky Fe3O4 composite with a rich heterogeneous interface via a simple synthetic process,which has shown amazing application potential in the field of electromagnetic wave absorption;In addition,based on the research of MXene/bacterial cellulose(BC)composite paper,we have also developed an all-solid-state micro-supercapacitor arrays(MSCAs)with excellent electrochemical properties,bendability,twistability and stretchability,which is an indispensable part for the development and construction of the power independent flexible/stretchable electronic system.The main research results are included as follows:1.To further improve the microwave absorption performance,with no introduction of complex components,we rationally designed and synthesized the composite of Fe3O4 flakes and reduced graphene oxide(RGO)with increased contact areas and enhanced interfacial polarization via hydrothermal method followed by H2 steam reduction.Compared with pure Fe3O4 flakes and RGO/granular Fe3O4 composite,the obtained composites of Fe3O4 flakes and RGO(RGO/Fe3O4)exhibit remarkable enhancement of microwave absorption.The measurement results indicate the maximum reflection loss of RGO/Fe3O4 can reach-47.2 dB at the thickness of 2.4 mm and the effective absorption bandwidth less than-10 dB reaches 6.4 GH2(from 11.36 GHz to 17.76 GHz),much higher than that of pure Fe3O4 flakes and RGO/granular Fe3O4 composite.The improved performances are believed to be from the rationally designed rich heterointerfaces,which are created by the combination of Fe3O4 flakes and graphene nanosheets.The construction of enhanced areas of heterointerfaces is also a valid strategy to improve the microwave absorption performance.2.Stretchable micropower sources with high energy density and stability under repeated tensile deformation are a key component for flexible/wearable microelectronics.Compared to conventional stretchable supercapacitors obtaining deformability depending on the sandwich electrodes configured in a wavy shape,the two-dimensional(2D)planar stretchable micro-supercapacitor arrays achieving stretchability through the tensile deformation of elastic/stretchable conductive frameworks would be a better choice for integration into usually planar stretchable electroniccircuits because of their more rational configuration.Although some impressive progresses in MSCAs have been made,developing an easily-manipulated and efficient protocol to fabricate stretchable MSCAs with both high areal capacitance and stability is still highly desired but of great challenge.Herein,through the combination of strain engineering and interlayer-spacing modulation,freestanding and lightweight MXene/bacterial cellulose composite papers with excellent mechanical stability and high electrochemical performance were desighed and prepared based on a facile all-solution-based paper making process.Followed an efficient laser-cutting kirigami patterning process,a bendable,twistable,and stretchable all-solid-state MSCAs were further fabricated.As expected,benefiting from the high-performance MXene/BC composite electrodes and rational sectional structure design,the resulting kirigami MSCAs exhibit areal capacitance as high as 111.5 mF cm-2,being stable under stretchingup to 100%,and bending or twisting state.The demonstrated combination of all-solution-based MXene/BC composite papers making method and easily-manipulated laser-cutting kirigami patterning technique enables the fabrication of MXene-based deformable all-solid-state planar MSCAs in a fast and efficient manner while achieving excellent areal performance metrics,making them promising compatible micropower sources for flexible/wearable microelectronics.