Probing the Domain Architecture in 2D α‐Mo₂C via Polarized Raman Spectroscopy

Abstract

MXenes are emerging 2D materials with intriguing properties such as excellent stability and high conductivity. Here, a systematic study on the Raman spectra of 2D α‐Mo2C (molybdenum carbide), a promising member in MXene family, is conducted. Six experimentally observed Raman modes from ultrathin α‐Mo2C crystal are first assigned with the assistance of phonon dispersion calculated from density functional theory. Angle‐resolved polarized Raman spectroscopy indicates the anisotropy of α‐Mo2C in the b–c plane. Raman spectroscopy is further used to study the unique domain structures of 2D α‐Mo2C crystals grown by chemical vapor deposition. A Raman mapping investigation suggests that most of the α‐Mo2C flakes contain multiple domains and the c‐axes of neighboring domains tend to form a 60° or 120° angle, due to the weak MoC bonds in this interstitial carbide and the low formation energy of the carbon chains along three equivalent directions. This study demonstrates that polarized Raman spectroscopy is a powerful and effective way to characterize the domain structures in α‐Mo2C, which will facilitate the further exploration of the domain‐structure‐related properties and potential applications of α‐Mo2C.

CVD synthesis and characterization of thin Mo2C crystals

“…The spectrum from point C in Figure 6A verifies the growth of graphene on the Cu as well, consistent with the above optical microscope results obtained by oxidation studies. In addition, we observed that some Mo 2 C crystals fell off during the transfer process, leaving behind regular shaped edge traces (B), as presented before in Ref [19]. Raman signals collected from this region (B) shows the absence of graphene underneath the Mo 2 C crystal.…”

“…CVD has been a promising technique to achieve large area and high quality thin layers of Mo 2 C 3,13,22,[14][15][16][17][18][19][20][21] . In this method, Cu foil is placed on a Mo substrate and heated.…”

Retracted: Emerging 2D MXene/Organic Heterostructures for Future Nanodevices

“…Recently, CVD grown molybdenum carbide (α-Mo 2 C structure) on copper foil has been reported. [206,207] On where, the deposition of methane vapor onto a bilayer substrate of copper foil sitting on a molybdenum foil resulted in a α-Mo 2 C structure. In this process, particularly same size of Cu and Mo foils (≈1 × 1 cm 2 of each) are first placed in the center of a 1 in.…”

Superconductivity in two-dimensional η-Mo3C2 films

“…The thickness collected at the same position decreases to 2.6 nm, indicating there is~0.4-nm-thick amorphous carbon film on the Mo-C films after the carbonization process. It is worth noting that this two-step deposition Raman spectroscopy is a powerful tool to probe the structural characteristics and properties of nanostructure materials, and it is sensitive to the vibration of different chemical bonds [25,26]. The Raman spectra of Mo-C films with different thicknesses are shown in Fig.…”