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Two-Dimensional MXenes Mo(2)Ti(2)C(3)Tz and Mo2TiC2Tz: Microscopic Conductivity and Dynamics of Photoexcited Carriers
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Two-Dimensional MXenes Mo(2)Ti(2)C(3)Tz and Mo2TiC2Tz: Microscopic Conductivity and Dynamics of Photoexcited Carriers

Guangjiang Lui, Varun Natu, Teng Shi, Michel W. Barsoum and Lyubov Titova
ACS applied energy materials, v 3(2), pp 1530-1539
01 Feb 2020

Abstract

Chemistry Chemistry, Physical Energy & Fuels Materials Science Materials Science, Multidisciplinary Physical Sciences Science & Technology Technology
MXenes are a recently discovered family of two-dimensional transition metal carbides, nitrides, and carbonitrides with electronic properties that can be tuned by their chemistry and structure. Herein THz spectroscopy was used to investigate the microscopic conductivity and photoexcited charge carrier dynamics in two Mo-based MXenes: Mo2Ti2C3Tz and Mo2TiC2Tz. We find that both have high intrinsic carrier densities (similar to 10(20) cm(-3) in Mo2Ti2C3Tz and similar to 10(19) cm(-3) in Mo2TiC2Tz) and mobilities and exhibit high conductivities within individual nanosheets. Optical 'excitations result in a transient conductivity increase in both compositions, in stark contrast with the most studied member of the MXene family, Ti3C2Tz, where photoexcitation suppresses the conductivity for nanoseconds. Deintercalation of water, and other species, from between the nanosheets by mild vacuum annealing at 200 degrees C further improves the long-range, internanosheet transport of the photoexcited carriers and increases their lifetime. High, and long-lived, photoinduced conductivity that can be engineered by substituting Mo for Ti renders these Mo-based MXenes attractive for a variety of optoelectronic, sensing, and photoelectrochemical applications.

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Collaboration types
Domestic collaboration
Web of Science research areas
Chemistry, Physical
Energy & Fuels
Materials Science, Multidisciplinary
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