Optimizing electronic structure of Mo_(2)TiC_(2)T_(x) MXene through Nb doping for enhanced electrochemical performance  

作　　者：Jingyuan Zhao Wenzheng Yan Zhaoxi Liu Xiaobin Liu Yapeng Tian Xinwei Cui 

机构地区：[1]Henan Institute of Advanced Technology,College of Materials Science and Engineering,Zhengzhou University,Zhengzhou 450003,China [2]College of Physics and Electronic Information Engineering,Guilin University of Technology,Guilin 514004,China

出　　处：《Nano Research》2024年第8期7174-7181,共8页纳米研究（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.52272242);the Provisional Key Research and Development Program of Henan Province(No.231111240600);the Natural Science Foundation of Henan Province(No.242300421428);the Start-up Funding for Scientific Research of Zhengzhou University(No.32310221).

摘　　要：MXene is a promising electrode material for both high volumetric capacitance and high-rate performance in supercapacitors.However,the current study has mainly focused on the monometallic element Ti_(3)C_(2)T_(x) MXene until now,while the bimetallic and multimetallic MXene have received comparatively less attention.In this work,we demonstrate that the electronic structure of the Mo_(2)TiC_(2)T_(x) MXene could be regulated by fine-tuning the content of doped Nb atoms.The enhanced electron cloud density of surface–O termination and the electron spin of the Mo atoms in the Mo_(2)TiC_(2)T_(x) MXene,leads to the boost of electric double-layer capacitor(EDLC)and improvement of pseudocapacitance.As a consequence,the electrochemical performance of Nb-doped Mo_(2)TiC_(2)T_(x) MXene(Nb-0.3-MXene)demonstrates a capacitance of 398 F·cm^(−3),roughly doubling that of the pristine Mo_(2)TiC_(2)T_(x) MXene electrode at 197 F·cm^(−3) in the 3 M H_(2)SO_(4) electrolyte.At the same time,the Nb-0.3-MXene could even maintain a capacitance of 82.75% at 200 mV·s−1,with high cyclic stability for 19,000 cycles at 10 A·g−1.Additionally,Nb-0.3-MXene-based hybrid supercapacitors deliver a remarkable volumetric energy density of 48.1 W·h·L^(−1)at 230.7 W·L^(−1),and 34.4 W·h·L^(−1)at a high power density of 82.6 kW·L^(−1).There exists a balance between the volumetric capacitance and rate performance with different ratios of Nb atoms in the Nb-doped MXene due to the strong interaction between the Nb-doped MXene and the intercalated protons.Therefore,optimizing the electronic structure of MXene through heteroatom doping is of great potential for enhanced supercapacitor performance.

关 键 词：niobium doping electronic structure Mo_(2)TiC_(2)T_(x)MXene electron spin rate performance volumetric capacitance 

分 类 号：O64[理学—物理化学]