Facile Tailoring of Surface Terminations of MXenes by Doping Nb Element: Toward Extraordinary Pseudocapacitance Performance

Jianguang Xu; Zhiyong Liu; Qiang Wang; Junsheng Li; Yuxiang Huang; Mengnan Wang; Linyu Cao; Wei Yao; Haijiang Wu; Chi Chen

doi:10.1021/acsami.2c21838

Facile Tailoring of Surface Terminations of MXenes by Doping Nb Element: Toward Extraordinary Pseudocapacitance Performance

ACS Appl Mater Interfaces. 2023 Mar 29;15(12):15367-15376. doi: 10.1021/acsami.2c21838. Epub 2023 Mar 16.

Authors

Jianguang Xu^{1

2}, Zhiyong Liu^{2

3}, Qiang Wang^{1

2}, Junsheng Li², Yuxiang Huang^{2

3}, Mengnan Wang², Linyu Cao², Wei Yao², Haijiang Wu^{3

4}, Chi Chen^{5

6}

Affiliations

¹ School of Materials and Energy, Shanghai Key Laboratory of Engineering Materials Application and Evaluation, Shanghai Polytechnic University, Shanghai 201209, P. R. China.
² School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, Jiangsu, P. R. China.
³ School of Mechanical and Energy Engineering, Shaoyang University, Shaoyang 422000, P. R. China.
⁴ Key Laboratory of Hunan Province for Efficient Power System and Intelligent Manufacturing, Shaoyang University, Shaoyang 422000, Hunan, P. R. China.
⁵ CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, P. R. China.
⁶ Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, and Xiamen Institute of Rare Earth Materials, Haixi Institute, Chinese Academy of Sciences, Xiamen 361021, P. R. China.

PMID: 36924166
DOI: 10.1021/acsami.2c21838

Abstract

MXenes show promising potential in supercapacitors due to their unique two-dimensional (2D) structure and abundant surface functional groups. However, most studies about MXenes have focused on tailoring surface structures by alternating synthesis methods or post-etch treatments, and little is known about the inherent relationship between surface groups and M elements. Herein, we propose a simple and novel strategy to adjust the surface structure of few-layered MXene flakes by adding a small amount of Nb element. Because of the strong affinity between Nb and O elements, the as-received V_1.8Nb_0.2CT_x and Ti_2.7Nb_0.3C₂T_x MXenes have much fewer -F functional groups and a higher O content than V₂CT_x and Ti₃C₂T_x MXenes, respectively. Thus, both V_1.8Nb_0.2CT_x and Ti_2.7Nb_0.3C₂T_x MXenes show enhanced pseudocapacitance performance. Especially, V_1.8Nb_0.2CT_x delivers an ultrahigh volumetric capacitance of 1698 F/cm³ at a scan rate of 2 mV/s. Moreover, benefiting from the high activity of MAX precursors obtained through a fast self-propagating high-temperature synthesis, the etching time to produce V-based MXenes is much shorter than that in previous reports. Therefore, the results presented here are applicable to the surface engineering and rational design of 2D MXene materials and develop them into promising, cost-effective electrode materials for supercapacitors or other energy-storage equipment.

Keywords: MXenes; V1.8Nb0.2CTx; V2CTx; solid solution; supercapacitors; surface terminations.