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Highly Enhanced Pseudocapacitive Performance of Vanadium‐Doped MXenes in Neutral Electrolytes
Author(s) -
Gao ZhiWen,
Zheng Weiran,
Lee Lawrence Yoon Suk
Publication year - 2019
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201902649
Subject(s) - mxenes , electrolyte , materials science , vanadium , doping , alkali metal , titanium carbide , inorganic chemistry , metal , pseudocapacitor , supercapacitor , titanium , capacitance , chemical engineering , electrode , nanotechnology , chemistry , optoelectronics , organic chemistry , engineering , metallurgy
2D titanium carbide (Ti 3 C 2 T x MXene) is recognized as a promising material for pseudocapacitor electrodes in acidic solutions, while the current studies in neutral electrolytes show much poorer performances. By a simple hydrothermal method, vanadium‐doped Ti 3 C 2 T x 2D nanosheets are prepared to tune the interaction between MXene and alkali metal adsorbates (Li + , Na + , and K + ) in the neutral electrolyte. Maintaining the 2D morphology of MXene, the coexisting V 3+ and V 4+ are confirmed to form surface V–C and V–O species. At a medium doping level of V:Ti = 0.17:1, the V‐doped MXene exhibits the highest capacitance of 365.9 F g −1 in 2 m KCl (10 mV s −1 ) and excellent stability (5% loss after 5000 cycles), compared to only 115.7 F g −1 of pristine MXene. Density functional theory calculations reveal the stronger alkali metal ion–O interaction on V‐doped MXene surface than unmodified MXene and a further capacitance boost to 404.9 F g −1 using Li + ‐containing neutral electrolyte is reported, which is comparable to the performance under acidic conditions.