Highly Enhanced Pseudocapacitive Performance of Vanadium-Doped MXenes in Neutral Electrolytes

TY - JOUR

T1 - Highly Enhanced Pseudocapacitive Performance of Vanadium-Doped MXenes in Neutral Electrolytes

AU - Gao, Zhi Wen

AU - Zheng, Weiran

AU - Lee, Lawrence Yoon Suk

N1 - Publisher Copyright: © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

PY - 2019/10/1

Y1 - 2019/10/1

N2 - 2D titanium carbide (Ti3C2Tx 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 Ti3C2Tx 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 V3+ and V4+ 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.

AB - 2D titanium carbide (Ti3C2Tx 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 Ti3C2Tx 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 V3+ and V4+ 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.

KW - TiCT MXene

KW - neutral electrolytes

KW - pseudocapacitors

KW - strong interaction

KW - vanadium doping

UR - http://www.scopus.com/inward/record.url?scp=85070775289&partnerID=8YFLogxK

U2 - 10.1002/smll.201902649

DO - 10.1002/smll.201902649

M3 - 文章

C2 - 31419018

AN - SCOPUS:85070775289

SN - 1613-6810

VL - 15

JO - Small

JF - Small

IS - 40

M1 - 1902649

ER -