# Research Progress and Applications of 2D Antimonene
## 2 Theoretical Research and Experimental Methods  
[PERSON] Theoretical Research  
Antimonene with different thickness has different electronic structure and optical properties, depending on its thickness. [PERSON] et al[PERSON] [18] studied the properties of 1-4 layers of antimonene through first principle, and the results showed that 1 L and 2 L have indirect band gaps by using PBE, HSE, and modified Van der Waals (FDT-2), and 3L and 4L exhibit metal properties[PERSON] At the same time, its reflection and absorption capacity were analyzed. The reflection spectrum is shown in Figure 1a. The emission coefficient increases with the increase in layers, but the focusing appears between 4-6 eV. The absorption coefficient is shown in Figure 1b. With the increase in layers, the peak value of the absorption curve redshifts, indicating that the larger the layer, the smaller the band gap. When the antimonene is transformed from antimonite to single-layer antimonene, its absorption peak moves from the visible region to the ultraviolet region, and the absorption of the ultraviolet region is greater than that of the longer wavelengths. According to the reflectance \(\delta R\)[29] and the absorbance (A) of the substrate and material with the refractive index of \(n_{subs}\), the following relationship holds:  
\[\delta R(\lambda)=\frac{4}{n_{subs}^{2}-1}A(\lambda) \tag{1}\]  
When the substrate is in the same medium, \(n_{subs}\) can be regarded as constant, that is, the reflection coefficient is related to the absorbance of the material. For two-dimensional materials, the absorbance of the material generally increases with the increase in the layer, that is, the reflection coefficient also increases. In 2015, [PERSON] et al. [30] theoretically calculated the stability of antimonene. The \(\alpha\)-phase Sb has two sublayers, and the atoms of the same layer are in different planes. The \(\beta\)-phase antimony structure is hexagonal lattice with curved surface. The stability of antimonene is studied by calculating phonon dispersion curve. The antimony phonon dispersion curves of \(\alpha\) and \(\beta\) phases have no hypothetical vibrating mode, which indicates their good stability, while the antimony of \(\gamma\) and \(\delta\) phases have virtual mode, indicating that their structures are not stable. [PERSON] et al. [31] calculated the thermal conductivity of antimonene from ab initio by combining the Boltzmann transport equation of phonons. The results showed that the lattice thermal conductivity of antimonene was 15.1 W/mK at 300 K, indicating that the low thermal conductivity of antimonene was caused by its small group velocity, low Debyetemperature and high flexion. [PERSON] et al. [32] also calculated the thermal conductivity of \(\alpha\) and \(\beta\) phase antimonenes theoretically, and at the same temperature and rough edges, \(\alpha\) has better thermally conductivity than \(\beta\)-phase antimonene, which is attributed to the difference in phonon energy spectrum and group velocity. The thermoelectric materials can use the thermoelectric effect to convert the waste electricity into electric energy, so antimonene has the application potential of the thermoelectric materials. In 2018, [PERSON] et al. [33] calculated the electron transport characteristics of \(\beta\)-phase antimonene nanoribbons (Z-SbNRs) based on the density function theory and non-equilibrium Green's function, and found that the length and width of the central scattering region have a great influence on the electron transport of antimonene. Under the same voltage, the current increases with the increase in the width of the band and decreases with the increase in the length. In 2020, [PERSON] et al. [34] also studied the electron transport characteristics of antimonene nanoribbons through first principles.