Gao Yushuan, Wang Yindong, Chen Chengxiang, Zhou Jun, Cheng Yonghong, Shi Le
Center of Nanomaterials for Renewable Energy (CNRE), State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, P. R. China.
Langmuir. 2022 Aug 30;38(34):10520-10529. doi: 10.1021/acs.langmuir.2c01320. Epub 2022 Aug 18.
Montmorillonite (MMT) is an abundant silicate mineral with ultrahigh stability. The exfoliation of stacked MMT into high-aspect-ratio nanosheets is of crucial importance for various applications such as toxic gas suppression, barrier property enhancement, flame retardancy, and ion conduction. In this work, we develop a new heating/rehydrating and gas-pushing method that can successfully exfoliate MMT into nanosheets with aspect ratios (600-5000) far higher than the currently reported values (1-120). The MMT first goes through a "starvation pretreatment" under different heating temperatures to improve its hydrophilicity and is then rehydrated in a hydrogen peroxide solution. The hydrogen peroxide in the MMT interlayer space can decompose into water and oxygen bubbles, thus finally leading to the exfoliation via gas-pushing while preserving the large lateral size (mainly in the range of 1-6 μm) of the nanosheets. By changing the pretreatment temperature and pH value of the hydrogen peroxide solution, the exfoliation performance can be tuned. This simple and low-cost exfoliation method is promising to achieve the mass production of MMT nanosheets with a high aspect ratio and may promote its application in various fields such as energy conversion, drug delivery, and photocatalysis.
蒙脱石（MMT）是一种储量丰富且具有超高稳定性的硅酸盐矿物。将堆叠的蒙脱石剥离成高纵横比的纳米片对于诸如有毒气体抑制、阻隔性能增强、阻燃性和离子传导等各种应用至关重要。在这项工作中，我们开发了一种新的加热/再水化和气体推动方法，该方法能够成功地将蒙脱石剥离成纵横比（600 - 5000）远高于目前报道值（1 - 120）的纳米片。蒙脱石首先在不同加热温度下进行“饥饿预处理”以提高其亲水性，然后在过氧化氢溶液中再水化。蒙脱石层间空间中的过氧化氢会分解成水和氧气泡，从而最终通过气体推动导致剥离，同时保留纳米片较大的横向尺寸（主要在1 - 6μm范围内）。通过改变预处理温度和过氧化氢溶液的pH值，可以调节剥离性能。这种简单且低成本的剥离方法有望实现高纵横比蒙脱石纳米片的大规模生产，并可能促进其在能量转换、药物递送和光催化等各个领域的应用。
