超临界CO2-超声场耦合剥离石墨宏量制备石墨烯及其柔性透明电极的构建

Macro-controllable preparation of high quality graphene with low cost, high efficiency is crucial to its scale application and future development. Considering the issues of liquid exfoliation for producing graphene, such as bad conductive rate, low production efficiency, organic solvent residues and environmental hazards, a new strategy of supercritical CO2 coupled with ultrasound is developed. By taking its advantages of low interface tension, high compressibility and diffusibility, solvent power, CO2 molecular is penetrated and inserted between the layers of graphite, and the graphite is exfoliated under the coordination effects of the mechanical and cavitation of the ultrasound with supercritical CO2. The exfoliating mechanism is investigated. The relationship of density and pressure of supercritical CO2, and the ultrasonic power, frequency and time with the layer numbers, size and conductivity of the graphene is determined, revealing the influencing rules of the coupled parameters. The exfoliation mechanisim of supercritical CO2 coupled with ultrasound field is established. The theoretical foundation and green scalable method are developed for preparation of graphene with controllable structure and performance based on supercritical CO2 coupled with ultrasound field. The graphene ink with high concentration and stability is studied. The theory and method of dispersing water-based graphene are developed. Inkjet printing of highly conductive flexible electrodes and fabricating graphene-electrodes-based flexible loudspeaker are explored. Research results are meaningful in terms of science and practice for the scalable manufacture of graphene and its application.

低成本、高效、宏量可控制备高质量石墨烯是决定其规模应用和未来发展的关键所在。针对液相剥离法制备的石墨烯导电性差、生产效率低、有机溶剂残留以及对环境危害等问题，提出超临界CO2—超声场耦合剥离新方法，以鳞片和膨胀石墨为原料，利用超临界CO2的低界面张力、高扩散性、溶剂化能力及其性质可调的特点，将CO2分子扩散、渗透插入到石墨的碳原子层间，在超声的机械和空化等效应耦合作用下剥离石墨；探索超临界CO2与超声场协同剥离机制，确定超临界CO2密度、压力和超声功率、频率和时间与目标物层数、尺度和导电性能的关系，揭示耦合参数影响规律，建立超临界CO2-超声场耦合宏量可控制备石墨烯的理论基础和绿色方法；研制高浓度、高稳定水基石墨烯墨水，建立石墨烯分散稳定的理论和方法；研究喷墨打印构建石墨烯基柔性电极，组装石墨烯基电极的柔性扬声器，研究成果对石墨烯规模化制备的理论基础和方法及其应用具有科学意义和实际价值。

石墨烯具有优异的热学、电学、大比表面积等优异性质,在柔性电子器件、储能、热管理材料和催化剂载体以及复合材料等领域具有广阔的应用前景。低成本、宏量可控制备高质量石墨烯是决定其规模应用和未来发展的关键所在。本项目构建了超临界CO2—超声场耦合和超临界CO2-超声--机械剪切外场力系统，建立了高质量和低成本宏量制备石墨烯的绿色方法。运用计算流体动力学（CFD）与实验相结合的方法，模拟了不同超声功率和压力对压力场、速度场、剪应力场和空化分布的影响。阐明了超声诱导的流体剪切力和系统中周期性的压力波动是剥离石墨为石墨烯的主要因素，考察了超声波频率、功率、超声方式和时间与超临界CO2密度、压力耦合以及剪切速度对石墨烯结构、形貌、层数、周边尺寸和性能的影响规律，研究了超临界CO2-超声-剪切协同剥离石墨制备石墨烯的方法，获得了石墨烯产率达到63%，其中5层以下产率达到79%的工艺条件，阐明了超临界CO2与超声耦合剪切协同增效剥离石墨制备石墨烯机制，揭示了超临界CO2-外场力耦合剥离方法的关键影响因素。建立了超临界CO2从石墨与石墨烯的混合物中分离纯化石墨烯的洗提方法，为高纯度石墨烯的制备提供了新思路。研制了高浓度、高分散和高稳定的水基石墨烯墨水，构建了石墨烯-银纳米线-石墨烯柔性透明电极。为了进一步获得高导电透明电极，建立了超高长径比银纳米线的绿色合成新方法，获得了平均直径为18nm，长度为70μm的银纳米线。提出了石墨烯在室温下催化断裂乙醇C-C键和硝酸银中N-O键形成C≡N的反应机制，建立了石墨烯自组装宏量制备一维石墨烯卷的新工艺以及从二维材料自组装制备一维卷的通用方法。分别从微观和宏观层面对所制备的石墨烯结构和性能进行了深入研究，石墨烯保持原有晶体结构，具有优异的电学和热学性能，其薄膜电导率达到∽106 S/m，在储能、导电墨水、柔性电子器件、电热膜和防腐涂层等方面的应用具有明显优势。研究成果为高质量、低成本、绿色和宏量制备石墨烯提供了理论基础和实验依据，对石墨烯的规模化应用具有实际意义。