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Abstract MXenes, a new class of 2D transition metal carbides, nitrides, and carbonitrides, have attracted much attention due to their outstanding properties. Here, we report the broadband spatial self‐phase modulation of Ti2CTxMXene nanosheets dispersed in deionized water in the visible to near‐infrared regime, highlighting the broadband nonlinear optical (NLO) response of Ti2CTxMXene. Using ultrafast pulsed laser excitation, the nonlinear refractive indexn2and the third‐order nonlinear susceptibilityof Ti2CTxMXene were measured to be ∼10−13m2/W and ∼ 10−10esu, respectively. Leveraging the large optical nonlinearity of Ti2CTxMXene, an all‐optical modulator in the visible regime was fabricated based on the spatial cross‐phase modulation effect. This work suggests that 2D MXenes are ideal broadband NLO materials with excellent prospects in NLO applications. image
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On a Two-Dimensional MoS 2 /Mo 2 CT x Hydrogen Evolution Catalyst Obtained by the Topotactic Sulfurization of Mo 2 CT x MXene
- Award ID(s):
- 1740795
- PAR ID:
- 10226430
- Date Published:
- Journal Name:
- Journal of The Electrochemical Society
- Volume:
- 167
- Issue:
- 12
- ISSN:
- 1945-7111
- Page Range / eLocation ID:
- 124507
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Garnering attention for high conductivity, nonlinear optical properties, and more, MXenes are water-processable 2D materials that are considered candidates for applications in electromagnetic interference shielding, optoelectronic and photonic devices among others. Herein we investigate the intrinsic and photoexcited conductivity in Nb 2 CT x, a MXene with reported high photothermal conversion efficiency. DFT calculations show that hydroxyl and/or fluorine-terminated or is metallic, in agreement with THz spectroscopy, which reveals the presence of free charge carriers that are highly localized over mesoscopic length scales. Photoexcitation of Nb 2 CT x, known to result in rapid heating of the crystal lattice, is found to produce additional free carriers and a transient enhancement of photoconductivity. Most photoexcited carriers decay over the sub-picosecond time scales while a small fraction remain for much longer, sub-nanoseconds, times.more » « less
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Two-dimensional, 2D, niobium carbide MXene, Nb2CTx, has attracted attention due to its extraordinarily high photothermal conversion efficiency that has applications ranging from medicine, for tumor ablation, to solar energy conversion. Here, we characterize its electronic properties and investigate the ultrafast dynamics of its photoexcitations with a goal of shedding light onto the origins of its unique properties. Through density functional theory, DFT, calculations, we find that Nb2CTx is metallic, with a small but finite DOS at the Fermi level for all experimentally relevant terminations that can be achieved using HF or molten salt etching of the parent MAX phase, including –OH, –O, –F, –Cl, –Br, –I. In agreement with this prediction, THz spectroscopy reveals an intrinsic long-range conductivity of ∼60 Ω−1 cm−1, with significant charge carrier localization and a charge carrier density (∼1020 cm−3) comparable to Mo-based MXenes. Excitation with 800 nm pulses results in a rapid enhancement in photoconductivity, which decays to less than 25% of its peak value within several picoseconds, underlying efficient photothermal conversion. At the same time, a small fraction of photoinjected excess carriers persists for hundreds of picoseconds and can potentially be utilized in photocatalysis or other energy conversion applications.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1149/1945-7111/abad6e
