Abstract
The transition metal carbide (TMC) family has been previously studied for various catalytic, mechanical, and electronic applications, and recently TMCs have been isolated into the ultrathin limit. A bottom-up approach has been developed to synthesize non-layered, ultrathin TMCs (UThTMCs). In this work, liquid metal assisted chemical vapor deposition is used to control the growth of different phases of tungsten carbide. In particular, WC and W2C single crystal nanoplates are synthesized when using copper and gallium, respectively, as the tungsten diffusion barrier. First principles calculations confirm the stability found experimentally in the two synthesized carbide phases. We also report the first low temperature measurements of electronic transport in WC below 300 mK and ultrathin W2C down to 1.8 K. We find that WC does not enter a superconducting state, while UThTMCs of W2C enter a quasi-2D superconducting state below 2.8 K. Our results provide new ground on the synthesis of other UThTMCs with controlled crystal phase. Given the richness of phases among metal carbides and the related transition metal nitride family, further research will be motivated by this work to isolate novel carbide and nitride phases in this ultrathin limit. Finally, it is important to note that the electronic transport of UThTMCs follows a quasi-2D regime and further systems should be evaluated and compared, especially the superconducting phases. These UThTMCs and their heterointerfaces could find important applications in electrocatalysis, carbide plasmonics, transparent conducting films, and materials for effective radiation shielding due to their high density and ability to absorb neutrons and gamma rays.
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Acknowledgements
This work was primarily supported by the Basic Office of Science of the Department of Energy under award number DE-SC0018025. Crystal structures generated using CrystalMaker, CrystalMaker Software Ltd, Oxford, England (www.crystalmaker.com). The schematic in Fig. 1a was made in Adobe Dimension. The authors are grateful to the Materials Characterization Laboratory at the Pennsylvania State University.
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M.T. and S.B.S. supervised the project. A.S. led the experimental design, sample preparation, and electronic transport analysis, and wrote the original manuscript draft. D.S. assisted with optimization of synthesis parameters, carried out planar and cross-sectional S/TEM, EDS, and SAED, and led the crystal structure analysis. J.W. performed and led DFT calculations with experimental corroboration with A.S. and D.S. D.Z. measured four-probe electronic transport in W2C platelets with in-plane and angle-dependent magnetic fields; out-of-plane magnetic field measurements were done by A.S. Z.Y. measured and analyzed AFM data for transferred WC and W2C in addition to the devices used for electronic transport. Z.Y. also measured and analyzed the XPS spectra of as-grown and transferred WC and W2C. L.Y. carried out electron beam lithography and evaporation of metal contacts to fabricate the WC and W2C devices, and performed the low temperature electronic transport properties of WC under the supervision of M.K. M.T., S.B.S., and M.K. revised and discussed the manuscript. All authors read, edited, and approved the final manuscript.
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M.T. is an Editorial Board Member of npj 2D Materials and Applications. M.T. was not involved in the journal’s review of, or decision related to, this manuscript. The other authors declare no competing financial or non-financial interests.
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Sredenschek, A.J., Sanchez, D., Wang, J. et al. Phase-controlled synthesis and two-dimensional electronic transport of ultrathin tungsten carbide platelets. npj 2D Mater Appl (2026). https://doi.org/10.1038/s41699-026-00676-3
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DOI: https://doi.org/10.1038/s41699-026-00676-3
