Preparation And Electrochemical Application Of 2D Reduced Graphene Oxide Self-assembled Film

Graphene has excellent physical properties and electrochemical properties.After years of research and development,graphene and graphene-based carbon materials have become important composite additives,cocatalysts and carbon skeleton materials.They have excellent electrical and thermal conductivity,high flexibility and low dimension properties.It plays an important role in energy storage devices,liquid crystal optical materials,molecular sieves.However,because of its ease of agglomeration,the preparation of high-quality 2D graphene film is difficult,which seriously hinders the research and application of graphene.In this paper,we will report a self-assembled graphene film obtained by thermal driving and chemical driving,and take this as a starting point to study and explore the application of this graphene film in electrochemistry.We prepared the graphene film by solvent evaporation assisted self-assembly method.The physicochemical properties were characterized it by SEM,Raman spectroscopy,FT-IR spectroscopy,AFM and four-probe resistance tester.By controlling the reaction conditions,the thickness can be controlled from 20 nm to 200 nm.As the thickness increases,the sheet resistance decreases from 830 KΩ/sq to 2.95 KΩ/sq.On the Raman spectrum,the low-thickness graphene film exhibited a distinct 2D peak(at 2653 cm-1).In the research,we found that the graphene film obtained in this way exhibits strong physical operability.Based on this,it is applied and explored in electrochemical applications.First of all,passivation of lithium metal anodes to mitigate unstable solid electrolyte interface and parasitic dendrite growth is the premise for their successful implementation in lithium metal batteries.Herein,aiming to simultaneously reduce the interfacial resistance and suppress lithium dendrites,we coat the lithium metal anodes with a two-dimensional(2D)graphene layer prepared via solvent evaporation assisted self-assembly.Upon lithiation/delithiation the graphene coating cracks into mosaic-like flakes,in between the interconnected gaps serve as the passage for uniform lithium plating/striping.Half cells composed of the sandwich Cu/Li/graphene electrode vs.Cu foils reveal much improved Li usage and Coulombic efficiencies.Through ex-situ SEM imaging and XPS depth profiling,a comprehensive view of Li intercalation,deposition,and dendrite suppression on the graphene coating is obtained.As a result of the improved kinetics of Li transportation,excellent electrochemical performances are demonstrated in the symmetric gLi II gLi cells with a stabilized overpotential of only 87.9 mV at 5 mA cm-2 over 600 cycles,and in Li-S batteries with a stabilized capacity of 1200 mAh g-1 at 1 C near 1000 cycles.Secondly,the Janus functional 2D graphene film is used for photocatalytic hydrogen production.Layered semiconductors are the most important photocatalysts,especially for visible light-induced hydrogen production by water decomposition.We have separately grown different semiconductor materials and catalyst materials on both sides of the self-assembled graphene film by hydrothermal method,and obtained a low-thickness two-dimensional Janus graphene film.The structure of the film was characterized by SEM,XPS and Raman spectroscopy.The RuO2/G/CdS film obtained by this method was subjected to photocatalytic hydrogen production test.Under the condition of no Nature photosensitizer,the production of hydrogen is 87 μmol h-1 g-1,the production of oxygen is 53 μmol h-1 g-1...