Supercritical CO2-Assisted Layer Exfoliation of MAX Ti3AlC2 Nanosheets Without Etching,Advanced Materials Technologies

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Supercritical CO2-Assisted Layer Exfoliation of MAX Ti3AlC2 Nanosheets Without Etching
Advanced Materials Technologies ( IF 6.4 ) Pub Date : 2024-03-12 , DOI: 10.1002/admt.202301437
Hyeri Kim ₁ , Dajeong Gwon ₂ , Dohyeong Kim ₂ , Jinho Kee ₂ , Jaseung Koo _{1,

2}

Affiliation

Although MAX exhibits excellent heat resistance, chemical resistance, and electrical conductivity due to its metallic and ceramic properties, the exfoliation of the MAX sheets with oxidation stability is a key issue in maximizing its advantages and improving its performance. In this study, the supercritical CO₂ (scCO₂) technique is employed to mechanically exfoliate MAX sheets without chemical etching. The supercritical fluid process is conducted in two continuous steps under different CO₂ conditions: supercritical drying and rapid exfoliation of the supercritical suspension (RESS). X-ray diffraction and scanning electron microscopy results reveal that both supercritical drying (45 °C and 100 bar) and RESS (100 °C and 120 bar) processes are required for MAX sheet exfoliation. During these processes, scCO₂ molecules are deeply intercalated into the MAX sheet interlayers. The scCO₂-treated MAX sheets and oxidized MXene exhibit electrical conductivities of 457, 303, and 46 S cm⁻¹ at 100 bar based on the powder resistivity measurement system. Because the layer exfoliation of MAX sheets is closely correlated with the performance of MAX-based materials, the technique employed in this study can provide a route for applications requiring expanded MAX, ranging from nanoelectronic devices to energy-storage materials such as supercapacitors and battery anodes.

中文翻译：

超临界 CO2 辅助层剥离 MAX Ti3AlC2 纳米片无需蚀刻

尽管MAX因其金属和陶瓷特性而表现出优异的耐热性、耐化学性和导电性，但具有氧化稳定性的MAX片材的剥离是最大限度地发挥其优势并提高其性能的关键问题。在本研究中，采用超临界CO ₂ (scCO _{2 ) 技术在不进行化学蚀刻的情况下机械剥离MAX 片材。超临界流体过程在不同的CO}₂条件下分两个连续步骤进行：超临界干燥和超临界悬浮液的快速剥离(RESS)。 X 射线衍射和扫描电子显微镜结果表明，MAX 片材剥离需要超临界干燥（45 °C 和 100 bar）和 RESS（100 °C 和 120 bar）工艺。在这些过程中，scCO ₂分子深深地嵌入到MAX片夹层中。根据粉末电阻率测量系统，经scCO _{2处理的MAX片和氧化MXene在100巴下表现出457、303和46 S cm}^-1的电导率。由于 MAX 片材的层剥离与 MAX 基材料的性能密切相关，因此本研究中采用的技术可以为需要扩展 MAX 的应用提供途径，从纳米电子器件到超级电容器和电池阳极等储能材料。

更新日期：2024-03-12

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