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Title: Control of electronic properties of 2D carbides (MXenes) by manipulating their transition metal layers

In this paper, a transition from metallic to semiconducting-like behavior has been demonstrated in two-dimensional (2D) transition metal carbides by replacing titanium with molybdenum in the outer transition metal (M) layers of M 3C 2 and M 4C 3 MXenes. The MXene structure consists of n + 1 layers of near-close packed M layers with C or N occupying the octahedral site between them in an [MX] nM arrangement. Recently, two new families of ordered 2D double transition metal carbides MXenes were discovered, M' 2M"C 2 and M' 2M" 2C 3 – where M' and M" are two different early transition metals, such as Mo, Cr, Ta, Nb, V, and Ti. The M' atoms only occupy the outer layers and the M" atoms fill the middle layers. In other words, M' atomic layers sandwich the middle M"–C layers. Using X-ray atomic pair distribution function (PDF) analysis on Mo 2TiC 2 and Mo 2Ti 2C 3 MXenes, we present the first quantitative analysis of structures of these novel materials and experimentally confirm that Mo atoms are in the outer layers of the [MC] nM structures. The electronic properties of these Mo-containing MXenes are compared with their Ti 3C 2 counterparts, andmore » are found to be no longer metallic-like conductors; instead the resistance increases mildly with decreasing temperatures. Density functional theory (DFT) calculations suggest that OH terminated Mo–Ti MXenes are semiconductors with narrow band gaps. Measurements of the temperature dependencies of conductivities and magnetoresistances have confirmed that Mo 2TiC 2T x exhibits semiconductor-like transport behavior, while Ti 3C 2T x is a metal. Finally, this finding opens new avenues for the control of the electronic and optical applications of MXenes and for exploring new applications, in which semiconducting properties are required.« less
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [3] ;  [1] ;  [4] ;  [1] ;  [1]
  1. Drexel Univ., Philadelphia, PA (United States)
  2. Columbia Univ., New York, NY (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Columbia Univ., New York, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-05CH11231; SC0012704; DMR-1534910; CRG 3; W911NF-15-1-0133
Accepted Manuscript
Journal Name:
Nanoscale Horizons
Additional Journal Information:
Journal Volume: 1; Journal Issue: 3; Journal ID: ISSN 2055-6756
Royal Society of Chemistry
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); Drexel Univ. (United States); King Abdullah Univ. of Science and Technology (KAUST) (Saudi Arabia); Army Research Office (United States)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1327611