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Title: Edge Segregated Polymorphism in 2D Molybdenum Carbide

Abstract

Molybdenum carbide (Mo 2C), a class of unterminated MXene, is endowed with rich polymorph chemistry, but the growth conditions of the various polymorphs are not understood. Other than the most commonly observed T-phase Mo 2C, little is known about other phases. Here, Mo 2C crystals are successfully grown consisting of mixed polymorphs and polytypes via a diffusion-mediated mechanism, using liquid copper as the diffusion barrier between the elemental precursors of Mo and C. By controlling the thickness of the copper diffusion barrier layer, the crystal growth can be controlled between a highly uniform AA-stacked T-phase Mo 2C and a “wedding cake” like Mo 2C crystal with spatially delineated zone in which the Bernal-stacked Mo 2C predominate. The atomic structures, as well as the transformations between distinct stackings, are simulated and analyzed using density functional theory (DFT)-based calculations. Bernal-stacked Mo 2C has a d band closer to the Fermi energy, leading to a promising performance in catalysis as verified in hydrogen evolution reaction (HER).

Authors:
 [1]; ORCiD logo [2];  [1];  [1];  [1];  [2]; ORCiD logo [2];  [3];  [1];  [1]
  1. National Univ. of Singapore (Singapore)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Chinese Academy of Sciences (CAS), Beijing (China)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1509533
Alternate Identifier(s):
OSTI ID: 1495241
Grant/Contract Number:  
AC05-00OR22725; DE‐AC02‐05CH11231; DE‐AC05‐00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Advanced Materials
Additional Journal Information:
Journal Volume: 31; Journal Issue: 15; Journal ID: ISSN 0935-9648
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Zhao, Xiaoxu, Sun, Weiwei, Geng, Dechao, Fu, Wei, Dan, Jiadong, Xie, Yu, Kent, Paul R., Zhou, Wu, Pennycook, Stephen J., and Loh, Kian Ping. Edge Segregated Polymorphism in 2D Molybdenum Carbide. United States: N. p., 2019. Web. doi:10.1002/adma.201808343.
Zhao, Xiaoxu, Sun, Weiwei, Geng, Dechao, Fu, Wei, Dan, Jiadong, Xie, Yu, Kent, Paul R., Zhou, Wu, Pennycook, Stephen J., & Loh, Kian Ping. Edge Segregated Polymorphism in 2D Molybdenum Carbide. United States. doi:10.1002/adma.201808343.
Zhao, Xiaoxu, Sun, Weiwei, Geng, Dechao, Fu, Wei, Dan, Jiadong, Xie, Yu, Kent, Paul R., Zhou, Wu, Pennycook, Stephen J., and Loh, Kian Ping. Wed . "Edge Segregated Polymorphism in 2D Molybdenum Carbide". United States. doi:10.1002/adma.201808343.
@article{osti_1509533,
title = {Edge Segregated Polymorphism in 2D Molybdenum Carbide},
author = {Zhao, Xiaoxu and Sun, Weiwei and Geng, Dechao and Fu, Wei and Dan, Jiadong and Xie, Yu and Kent, Paul R. and Zhou, Wu and Pennycook, Stephen J. and Loh, Kian Ping},
abstractNote = {Molybdenum carbide (Mo2C), a class of unterminated MXene, is endowed with rich polymorph chemistry, but the growth conditions of the various polymorphs are not understood. Other than the most commonly observed T-phase Mo2C, little is known about other phases. Here, Mo2C crystals are successfully grown consisting of mixed polymorphs and polytypes via a diffusion-mediated mechanism, using liquid copper as the diffusion barrier between the elemental precursors of Mo and C. By controlling the thickness of the copper diffusion barrier layer, the crystal growth can be controlled between a highly uniform AA-stacked T-phase Mo2C and a “wedding cake” like Mo2C crystal with spatially delineated zone in which the Bernal-stacked Mo2C predominate. The atomic structures, as well as the transformations between distinct stackings, are simulated and analyzed using density functional theory (DFT)-based calculations. Bernal-stacked Mo2C has a d band closer to the Fermi energy, leading to a promising performance in catalysis as verified in hydrogen evolution reaction (HER).},
doi = {10.1002/adma.201808343},
journal = {Advanced Materials},
number = 15,
volume = 31,
place = {United States},
year = {2019},
month = {2}
}

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