01754nas a2200205   4500008004100000022001400041245011500055210006900170260000900239300001600248490000700264520103300271100001901304700001601323700001601339700001501355700002401370700002401394856013001418       2022                        eng d  a2050-748800aUnderstanding the effect of sodium polyphosphate on improving the chemical stability of Ti3C2Tz MXene in water0 aUnderstanding the effect of sodium polyphosphate on improving th  cOCT   a22016-220240 v103 a<p>
	Degradation of MXenes in aqueous environments severely limits the application and industrialization of this large family of two-dimensional (2D) materials. Hydrolysis and oxidation are now considered as two main degradation mechanisms and while significant efforts have been directed to prolonging the shelf-life of MXenes, separating and studying their degradation mechanisms have lagged behind. Herein, gas analysis via gas chromatography and Raman spectroscopy were used to investigate the effect of sodium polyphosphate, PP, on the degradation of Ti3C2Tz MXene. Transmission and scanning electron microscopies, as well as X-ray photoelectron spectroscopywere also used as complimentary techniques to support conclusions derived from gas analysis and to confirm the extent of degradation via characterization of solid reaction products. Based on these studies we have determined that the addition of PP to an equal mass of Ti3C2Tz solution can effectively suppress hydrolysis and protect Ti3C2Tz from degradation.</p>
1 aHuang, Shuohan1 aNatu, Varun1 aTao, Jingyi1 aXia, Yumin1 aMochalin, Vadym, N.1 aBarsoum, Michel, W.  uhttps://library.ncl.res.in/content/understanding-effect-sodium-polyphosphate-improving-chemical-stability-ti3c2tz-mxene-water02275nas a2200289   4500008004100000022001400041245007000055210006900125260000800194490000700202520140500209653001801614653001101632653002301643653001301666653002701679100002301706700002301729700002101752700001701773700001601790700001301806700002001819700002401839700002301863856009901886       2023                        eng d  a0935-964800aUltrafast spectroscopy of plasmons and free carriers in 2D MXenes0 aUltrafast spectroscopy of plasmons and free carriers in 2D MXene  cFEB0 v353 a<p>
	2D MXenes have diverse and chemically tunable optical properties that arise from an interplay between free carriers, interband transitions, and plasmon resonances. The nature of photoexcitations and their dynamics in three different members of the MXene family, Ti3C2, Mo2Ti2C3, and Nb2C, are investigated using two complementary pump-probe techniques, transient optical absorption, and time-resolved terahertz (THz) spectroscopy. Measurements reveal pronounced plasmonic effects in the visible and near-IR in all three. Optical excitation, with either 400 or 800 nm pulses, results in a rapid increase in lattice temperature, evidenced by a pronounced broadening of the plasmon mode that presents as a plasmon bleach in transient absorption measurements. Observed kinetics of plasmon bleach recovery provide a means to monitor lattice cooling. Remarkably slow cooling, proceeding over hundreds of picoseconds to nanoseconds time scales, implies MXenes have low thermal conductivities. The slowest recovery kinetics are observed in the MXene with the highest free carrier density, viz. Ti3C2, that supports phonon scattering by free carriers as a possible mechanism limiting thermal conductivity. These new insights into photoexcitation dynamics can facilitate their applications in photothermal solar energy conversion, plasmonic devices, and even photothermal therapy and drug delivery.</p>
10a2D properties10aMXenes10aOptical properties10aplasmons10aultrafast spectroscopy1 aColin-Ulloa, Erika1 aFitzgerald, Andrew1 aMontazeri, Kiana1 aMann, Javery1 aNatu, Varun1 aNgo, Ken1 aUzarski, Joshua1 aBarsoum, Michel, W.1 aTitova, Lyubov, V.  uhttps://library.ncl.res.in/content/ultrafast-spectroscopy-plasmons-and-free-carriers-2d-mxenes