Ames Laboratory; Chemistry
Ames Laboratory, Chemistry
Journal of Physical Chemistry C
Since the discovery of two-dimensional transition metal carbides, referred to as MXenes, research efforts have targeted their applications in energy storage, as lithium-ion batteries and supercapacitors. This interest is attributable to MXenes’ large volumetric capacitance, high rate handling capability, and stable cycling performance, which largely rely on the surface chemistry provided by the terminating groups, such as −OH, −O, and −F. However, the atomic-scale characterization of these surface terminations is challenging for diffraction methods. Solid-state (SS)NMR spectroscopy, especially 1H SSNMR, is a promising approach for scrutinizing the surface terminations and the intercalated water on an atomistic-scale; yet, only a few SSNMR studies of MXenes have been reported to date, offering conflicting results and limited understanding of −OH terminations. Here, we used 1H SSNMR experiments in concert with the DFT calculations of NMR parameters to identify multiple types of −OH groups residing on the external and internal surfaces in a commonly studied MXene, Ti3C2Tx. The study also identifies bulklike water trapped between the MXene flakes and interfacial water stranded on the surface. Lastly, two-dimensional 1H–1H correlation spectra elucidated the water–surface interactions and the mechanism of water deintercalation upon annealing.
DOE Contract Number(s)
Department of Energy Subject Categories
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Iowa State University Digital Repository, Ames IA (United States)