Alijani Hossein, Rezk Amgad R, Khosravi Farsani Mohammad Mehdi, Ahmed Heba, Halim Joseph, Reineck Philipp, Murdoch Billy J, El-Ghazaly Ahmed, Rosen Johanna, Yeo Leslie Y
Micro/Nanophysics Research Laboratory, RMIT University, Melbourne, VIC 3000, Australia.
Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping SE-58183, Sweden.
ACS Nano. 2021 Jul 27;15(7):12099-12108. doi: 10.1021/acsnano.1c03428. Epub 2021 Jun 29.
The conversion of layered transition metal carbides and/or nitrides (MXenes) into zero-dimensional structures with thicknesses and lateral dimensions of a few nanometers allows these recently discovered materials with exceptional electronic properties to exploit the additional benefits of quantum confinement, edge effects, and large surface area. Conventional methods for the conversion of MXene nanosheets and quantum dots, however, involve extreme conditions such as high temperatures and/or harsh chemicals that, among other disadvantages, lead to significant degradation of the material as a consequence of their oxidation. Herein, we show that the large surface acceleration-on the order of 10 million 's-produced by high-frequency (10 MHz) nanometer-order electromechanical vibrations on a chip-scale piezoelectric substrate is capable of efficiently nebulizing, and consequently dimensionally reducing, a suspension of multilayer TiCT (MXene) into predominantly monolayer nanosheets and quantum dots while, importantly, preserving the material from any appreciable oxidation. As an example application, we show that the high-purity MXene quantum dots produced using this room-temperature chemical-free synthesis method exhibit superior performance as electrode materials for electrochemical sensing of hydrogen peroxide compared to the highly oxidized samples obtained through conventional hydrothermal synthesis. The ability to detect concentrations as low as 5 nM is a 10-fold improvement to the best reported performance of TiCT MXene electrochemical sensors to date.
将层状过渡金属碳化物和/或氮化物（MXenes）转化为厚度和横向尺寸为几纳米的零维结构，可使这些最近发现的具有优异电子特性的材料利用量子限制、边缘效应和大表面积带来的额外优势。然而，将MXene纳米片和量子点转化的传统方法涉及高温和/或苛刻化学物质等极端条件，这些条件除了其他缺点外，还会由于材料氧化而导致其显著降解。在此，我们表明，在芯片级压电基板上由高频（10 MHz）纳米级机电振动产生的高达1000万倍的大表面加速度，能够有效地雾化并因此减小多层TiCT（MXene）悬浮液的尺寸，使其主要成为单层纳米片和量子点，同时重要的是，保护材料不发生任何明显的氧化。作为一个示例应用，我们表明，与通过传统水热合成获得的高度氧化样品相比，使用这种室温无化学合成方法制备的高纯度MXene量子点作为过氧化氢电化学传感的电极材料表现出优异的性能。检测低至5 nM浓度的能力比迄今为止报道的TiCT MXene电化学传感器的最佳性能提高了10倍。
