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Adv Mater. 2018 May;30(21):e1706409. doi: 10.1002/adma.201706409. Epub 2018 Apr 6.

W-Based Atomic Laminates and Their 2D Derivative W1.33 C MXene with Vacancy Ordering.

Author information

1
Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83, Linköping, Sweden.
2
Chemical Physics, Department of Physics, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.
3
Department of Chemical and Biological Engineering, Drexel University, Philadelphia, 19104 PA, USA.
4
Department of Materials Science and Engineering, Drexel University, Philadelphia, 19104, PA, USA.

Abstract

Structural design on the atomic level can provide novel chemistries of hybrid MAX phases and their MXenes. Herein, density functional theory is used to predict phase stability of quaternary i-MAX phases with in-plane chemical order and a general chemistry (W2/3 M21/3 )2 AC, where M2 = Sc, Y (W), and A = Al, Si, Ga, Ge, In, and Sn. Of over 18 compositions probed, only two-with a monoclinic C2/c structure-are predicted to be stable: (W2/3 Sc1/3 )2 AlC and (W2/3 Y1/3 )2 AlC and indeed found to exist. Selectively etching the Al and Sc/Y atoms from these 3D laminates results in W1.33 C-based MXene sheets with ordered metal divacancies. Using electrochemical experiments, this MXene is shown to be a new, promising catalyst for the hydrogen evolution reaction. The addition of yet one more element, W, to the stable of M elements known to form MAX phases, and the synthesis of a pure W-based MXene establishes that the etching of i-MAX phases is a fruitful path for creating new MXene chemistries that has hitherto been not possible, a fact that perforce increases the potential of tuning MXene properties for myriad applications.

KEYWORDS:

MXene; density functional theory; hydrogen evolution reaction; i-MAX phase; tungsten

PMID:
29633399
DOI:
10.1002/adma.201706409

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