Synthesis, characterization and chemistry of two-dimensional transition metal carbides and nitrides (MXenes)
"MXenes represent a relatively new and quickly growing family of two-dimensional (2D) early transition-metal carbides and nitrides first synthesized in 2011 from bulk layered crystalline MAX phases. Because of their 2D structure and unique combination of high conductivity and hydrophilicity, MXenes have raised a significant interest for various applications. However, it has been found that in some cases colloidal MXene flakes are not stable and can spontaneously degrade on a time scale from hours to days. In this work, we investigate the crucial factors for MXene degradation and demonstrate gas analysis as a powerful method to gain further insights into chemical reactivity of MXenes. The degradation rates of MXenes in water were further investigated depending on their monolayer thickness within the same chemical composition, as well as depending on chemical composition of the materials within the same monolayer thickness. We further demonstrate the role of chemical properties and reactivity of MXenes in some of their applications, in particular, related to tribology and adhesion. We investigated the tribological properties of Ti3C2 MXene and MXene/graphene coatings. We have observed that with a careful control of the environment in order to suppress undesirable chemical decomposition of MXenes, the friction of MXene coated silicon substrates can be reduced to superlubric regime. We also studied adhesion of MXenes to silicon using atomic force microscopy. The obtained adhesion evnergies of two types of MXenes to silicon do not depend on the number of MXene monpayers in a stack and are comparable with that of graphene to silicon, showing a great potential of MXenes for (opto)electronic device assembly"--Abstract, p. iv
Chemistry, Physical Sciences and Mathematics
Missouri University of Science and Technology
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