Echols Ian J, An Hyosung, Yun Junyeong, Sarang Kasturi T, Oh Ju-Hyun, Habib Touseef, Zhao Xiaofei, Cao Huaixuan, Holta Dustin E, Radovic Miladin, Green Micah J, Lutkenhaus Jodie L
Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States.
Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States.
Langmuir. 2021 Sep 28;37(38):11338-11350. doi: 10.1021/acs.langmuir.1c01904. Epub 2021 Sep 15.
MXenes, 2D nanomaterials derived from ceramic MAX phases, have drawn considerable interest in a wide variety of fields including energy storage, catalysis, and sensing. There are many possible MXene compositions due to the chemical and structural diversity of parent MAX phases, which can bear different possible metal atoms "M", number of layers, and carbon or nitrogen "X" constituents. Despite the potential variety in MXene types, the bulk of MXene research focuses upon the first MXene discovered, TiCT. With the recent discovery of polymer/MXene multilayer assemblies as thin films and coatings, there is a need to broaden the accessible types of multilayers by including MXenes other than TiCT; however, it is not clear how altering the MXene type influences the resulting multilayer growth and properties. Here, we report on the first use of MXenes other than TiCT, specifically TiCT and NbCT, for the layer-by-layer (LbL) assembly of polycation/MXene multilayers. By comparing these MXenes, we evaluate both how changing M (Ti Nb) and "" (TiCT TiCT) affect the growth and properties of the resulting multilayer. Specifically, the aqueous LbL assembly of each MXene with poly(diallyldimethylammonium) into films and coatings is examined. Further, we compare the oxidative stability, optoelectronic properties (refractive index, absorption coefficient, optical conductivity, and direct and indirect optical band gaps), and the radio frequency heating response of each multilayer. We observe that MXene multilayers with higher "" are more electrically conductive and oxidatively stable. We also demonstrate that NbCT containing films have lower optical band gaps and refractive indices at the cost of lower electrical conductivities as compared to their TiCT counterparts. Our work demonstrates that the properties of MXene/polycation multilayers are highly dependent on the choice of constituent MXene and that the MXene type can be altered to suit specific applications.
MXenes是源自陶瓷MAX相的二维纳米材料，在包括能量存储、催化和传感在内的广泛领域引起了相当大的关注。由于母体MAX相的化学和结构多样性，存在许多可能的MXene组成，其可以承载不同的可能金属原子“M”、层数以及碳或氮“X”成分。尽管MXene类型存在潜在的多样性，但大部分MXene研究集中在最早发现的MXene，即TiCT上。随着最近聚合物/MXene多层组装体作为薄膜和涂层的发现，有必要通过纳入除TiCT之外的MXene来拓宽可获得的多层类型；然而，尚不清楚改变MXene类型如何影响所得多层的生长和性能。在此，我们报告了首次使用除TiCT之外的MXene，特别是TiCT和NbCT，用于聚阳离子/MXene多层的逐层（LbL）组装。通过比较这些MXene，我们评估了改变M（Ti与Nb）和“X”（TiCT与TiCT）如何影响所得多层的生长和性能。具体而言，研究了每种MXene与聚（二烯丙基二甲基氯化铵）在水中的LbL组装成膜和涂层的情况。此外，我们比较了每种多层的氧化稳定性、光电性能（折射率、吸收系数、光导率以及直接和间接光学带隙）和射频加热响应。我们观察到具有较高“X”的MXene多层更具导电性和氧化稳定性。我们还证明，与TiCT对应物相比，含NbCT的薄膜具有较低的光学带隙和折射率，但以较低的电导率为代价。我们的工作表明，MXene/聚阳离子多层的性能高度依赖于组成MXene的选择，并且可以改变MXene类型以适应特定应用。
