Investigation of vacancy-ordered Mo1.33C MXene from first principles and x-ray photoelectron spectroscopy
2017 (English)In: Physical Review Materials, E-ISSN 2475-9953, Vol. 1, no 4, article id 044002Article in journal (Refereed) Published
Abstract [en]
MXenes are a comparatively young class of 2D materials, composed of transition-metal carbides/nitrides of the general formula Mn+1XnTx, where T represents surface terminations, typically O, OH, and/or F. Recently, a new type of MXene with vacancy ordering was discovered, Mo1.33CTx, with conduction and capacitance superior to the MXene counterpart without vacancies, Mo2CTx. We here present a theoretical evaluation of Mo1.33CTx based on first-principles calculations, where x = 2 and T is O, F, OH, or a mixture thereof. In addition to structural evaluation upon vacancy formation, we identify preferred terminations as well as termination sites, and resulting dynamical stability and electronic properties. For mixed terminations, the mixing energy is evaluated. We show that while Mo2C is typically O terminated, mixed terminations with a high F content are suggested for Mo1.33CTx, which in turn gives the highest metallicity out of all the configurations investigated. In addition, the results indicate a strong tuning potential of the band gap through choice of terminations, with an electronic structure changing between insulating and metallic depending on termination(s) and their configuration. We also performed x-ray photoelectron spectroscopy to identify and quantify the terminating species on the MXene, as well as their respective binding energies. The experimental results are consistent with the theoretical analysis, and combined they suggest an explanation to the MXene chemistry as well as the reported high conductivity of Mo1.33CTx.
Place, publisher, year, edition, pages
AMER PHYSICAL SOC , 2017. Vol. 1, no 4, article id 044002
National Category
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:liu:diva-143742DOI: 10.1103/PhysRevMaterials.1.044002ISI: 000416576300003OAI: oai:DiVA.org:liu-143742DiVA, id: diva2:1166701
Note
Funding Agencies|Swedish Research Council (VR) [642-2013-8020, 2014-4750]; Knut and Alice Wallenberg (KAW) Foundation [KAW 2015.0043]; SSF synergy grant FUNCASE; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]
2017-12-152017-12-152020-12-15