Zhang Jizhen, Kong Na, Hegh Dylan, Usman Ken Aldren S, Guan Guangwu, Qin Si, Jurewicz Izabela, Yang Wenrong, Razal Joselito M
Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216, Australia.
School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216, Australia.
ACS Appl Mater Interfaces. 2020 Jul 29;12(30):34032-34040. doi: 10.1021/acsami.0c06728. Epub 2020 Jul 16.
Two-dimensional titanium carbide (TiCT), or MXene, is a new nanomaterial that has attracted increasing interest due to its metallic conductivity, good solution processability, and excellent energy storage performance. However, TiCT MXene flakes suffer from degradation through oxidation due to prolonged exposure to oxygenated water. Preventing the occurrence of oxidation, i.e., the formation of TiO particles, was found to be crucial in maintaining MXene quality. In the present work, we found that freezing aqueous MXene dispersions at a low temperature can effectively prevent the formation of TiO nanoparticles at the flake edge, which is known as the early stage of oxidation. The TiCT flakes in frozen dispersion remain consistent in morphology and elemental composition for over 650 days, compared with freshly synthesized MXene, which in contrast exhibits flake edge degradation within two days when stored at room temperature. This result suggests that freezing a MXene dispersion dramatically postpones the oxidation of MXene flakes and that the stored MXene dispersion can be treated as freshly prepared MXene. This work not only fundamentally fulfilled the study on temperature dependence of MXene oxidation but has also demonstrated a simple method to extend the shelf life of MXene aqueous dispersion to years, which will be a cornerstone for large-scale production of MXene and ultimately benefit the research on MXenes.
二维碳化钛（TiCT），即MXene，是一种新型纳米材料，因其具有金属导电性、良好的溶液可加工性和优异的储能性能而受到越来越多的关注。然而，由于长时间暴露于含氧水中，TiCT MXene薄片会因氧化而降解。防止氧化的发生，即防止TiO颗粒的形成，对于维持MXene的质量至关重要。在本研究中，我们发现低温冷冻MXene水分散体可以有效防止薄片边缘TiO纳米颗粒的形成，这是氧化的早期阶段。与新鲜合成的MXene相比，冷冻分散体中的TiCT薄片在超过650天的时间里形态和元素组成保持一致，而新鲜合成的MXene在室温下储存两天内就会出现薄片边缘降解。这一结果表明，冷冻MXene分散体可显著推迟MXene薄片的氧化，并且储存的MXene分散体可被视为新鲜制备的MXene。这项工作不仅从根本上完成了对MXene氧化温度依赖性的研究，还展示了一种将MXene水分散体保质期延长至数年的简单方法，这将是MXene大规模生产的基石，并最终造福于MXene的研究。
