Michałowski Paweł P, Anayee Mark, Mathis Tyler S, Kozdra Sylwia, Wójcik Adrianna, Hantanasirisakul Kanit, Jóźwik Iwona, Piątkowska Anna, Możdżonek Małgorzata, Malinowska Agnieszka, Diduszko Ryszard, Wierzbicka Edyta, Gogotsi Yury
Łukasiewicz Research Network-Institute of Microelectronics and Photonics, Warsaw, Poland.
A. J. Drexel Nanomaterials Institute and Department of Materials Science and Engineering, Drexel University, Philadelphia, PA, USA.
Nat Nanotechnol. 2022 Nov;17(11):1192-1197. doi: 10.1038/s41565-022-01214-0. Epub 2022 Sep 22.
The MXene family of two-dimensional transition metal carbides and nitrides already includes ~50 members with distinct numbers of atomic layers, stoichiometric compositions and solid solutions, in-plane or out-of-plane ordering of atoms, and a variety of surface terminations. MXenes have shown properties that make them attractive for applications ranging from energy storage to electronics and medicine. Although this compositional variability allows fine-tuning of the MXene properties, it also creates challenges during the analysis of MXenes because of the presence of multiple light elements (for example, H, C, N, O, and F) in close proximity. Here, we show depth profiling of single particles of MXenes and their parent MAX phases with atomic resolution using ultralow-energy secondary-ion mass spectrometry. We directly detect oxygen in the carbon sublattice, thereby demonstrating the existence of oxycarbide MXenes. We also determine the composition of adjacent surface termination layers and show their interaction with each other. Analysis of the metal sublattice shows that MoTiAlC MAX exhibits perfect out-of-plane ordering, whereas CrTiAlC MAX exhibits some intermixing between Cr and Ti in the inner transition metal layer. Our results showcase the capabilities of the developed secondary-ion mass spectrometry technique to probe the composition of layered and two-dimensional materials with monoatomic-layer precision.
二维过渡金属碳化物和氮化物的MXene家族已经包含约50个成员，它们具有不同的原子层数、化学计量组成和固溶体、原子的面内或面外排列以及各种表面终止结构。MXene已展现出的特性使其在从能量存储到电子学和医学等一系列应用中具有吸引力。尽管这种成分的可变性允许对MXene的特性进行微调，但由于存在多个紧邻的轻元素（例如H、C、N、O和F），这也给MXene的分析带来了挑战。在此，我们使用超低能二次离子质谱对MXene及其母体MAX相的单个颗粒进行了具有原子分辨率的深度剖析。我们直接检测到了碳亚晶格中的氧，从而证明了碳氧化物MXene的存在。我们还确定了相邻表面终止层的组成，并展示了它们之间的相互作用。对金属亚晶格的分析表明，MoTiAlC MAX呈现出完美的面外排列，而CrTiAlC MAX在内部过渡金属层中Cr和Ti之间存在一些混合。我们的结果展示了所开发的二次离子质谱技术以单原子层精度探测层状和二维材料组成的能力。
