Jing Hongyue, Yeo Hyeonwoo, Lyu Benzheng, Ryou Junga, Choi Seunghyuk, Park Jin-Hong, Lee Byoung Hun, Kim Yong-Hoon, Lee Sungjoo
SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea.
School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST),291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea.
ACS Nano. 2021 Jan 26;15(1):1388-1396. doi: 10.1021/acsnano.0c08664. Epub 2021 Jan 5.
The physical and chemical properties of MXenes are strongly dependent on surface terminations; thus, the tailoring of surface functional groups in two-dimensional transition-metal carbides (MXenes) may extend the applicability of these compelling materials to a wider set of fields. In this work, we demonstrate the chemical modification of TiCT MXene diazonium covalent chemistry and the subsequent effects on the electrical properties of MXene. The 4-nitrophenyl group was grafted onto the surface of MXene through a solid-liquid reaction, which was confirmed by various characterization methods, including X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, electron energy loss spectroscopy, atomic force microscopy, and transmission electron microscopy. The degree of modification of MXene is expediently tunable by adjusting the concentration of the diazonium salt solution. The work function of functionalized MXene is modifiable by regulating the quantity of grafted diazonium surface groups, with an adjustable range of around 0.6 eV. Further, in this study, the electrical properties of modified MXene are investigated through the fabrication of field-effect-transistor devices that utilize modified MXene as a channel material. It was demonstrated that with increasing concentration of 4-nitrophenyl groups grafted onto the surface the on/off current ratio of the modified MXene was improved to as much as 3.56, with a corresponding decrease in conductivity and mobility. The proposed approach of controlled modification of surface groups in TiCT may imbue TiCT with favorable electronic behaviors and demonstrate prospects for use in electronic field applications.
MXenes的物理和化学性质强烈依赖于表面终端；因此，二维过渡金属碳化物（MXenes）表面官能团的定制可能会将这些引人注目的材料的适用性扩展到更广泛的领域。在这项工作中，我们展示了通过重氮共价化学对TiCT MXene进行化学修饰以及随后对MXene电学性质的影响。通过固液反应将4-硝基苯基接枝到MXene表面，这通过各种表征方法得到证实，包括X射线光电子能谱、傅里叶变换红外光谱、电子能量损失光谱、原子力显微镜和透射电子显微镜。通过调节重氮盐溶液的浓度可以方便地调节MXene的修饰程度。通过调节接枝的重氮表面基团的数量，可以改变功能化MXene的功函数，可调范围约为0.6 eV。此外，在本研究中，通过制造以修饰后的MXene作为沟道材料的场效应晶体管器件来研究修饰后MXene的电学性质。结果表明，随着接枝到表面的4-硝基苯基浓度的增加，修饰后MXene的开/关电流比提高到3.56，同时电导率和迁移率相应降低。所提出的对TiCT表面基团进行可控修饰的方法可能会赋予TiCT良好的电子行为，并展示其在电子领域应用的前景。
