MoSi2N4 single-layer: a novel two-dimensional material with outstanding mechanical, thermal, electronic, optical, and photocatalytic properties

Abstract

Very recently, the two-dimensional (2D) form of MoSi2N4 has been successfully fabricated [Hong et al., Sci. 369, 670 (2020)]. Motivated by theses recent experimental results, herein we investigate the structural, mechanical, thermal, electronic, optical and photocatalytic properties using hybrid density functional theory (HSE06-DFT). Phonon band dispersion calculations reveal the dynamical stability of MoSi2N4 monolayer structure. Furthermore, the mechanical study confirms the stability of MoSi2N4 monolayer. As compared to the corresponding value of graphene, we find the Young's modulus decreases by ∼ 30% while the Poisson's ratio increases by ∼ 30%. In addition, its work function is very similar to that of phosphorene and MoS2 monolayers. The electronic structure investigation shows the MoSi2N4 monolayer is an indirect bandgap semiconductor. We have determined the bandgap using the HSE06 (GGA) is 2.35 (1.79) eV, which is an overestimated (underestimated) value of the experimental bandgap (1.99 eV). The thermoelectric study shows a good thermoelectric performance of the MoSi2N4 monolayer with a figure of merit slightly larger than unity at high temperatures. The optical analysis using the RPA method constructed over HSE06 shows that the first absorption peak of the MoSi2N4 monolayer for in-plane polarization is located in the visible range of spectrum, i.e. it is a promising candidate for advancing optoelectronic nanodevices. The photocatalytic study indicates the MoSi2N4 monloayer can be a promising photocatalyst for water splitting as well as and CO2 reduction. In summary, the fascinating MoSi2N4 monloayer is a promising 2D material in many applications due to its unique physical properties.

Strain effects on monolayer MoSi2N4: Ideal strength and failure mechanism

“…MoN 2 layer is bonded to SiN layers via vertical Si-N bonds with Mo atom located at the center of the trigonal building block of six N atoms. The optimized lattice constants are a=b=2.911 Å, which are in excellent agreement with the previous results [15,17] The tensile strains of monolayer MoSi 2 N 4 are applied in either biaxial or uniaxial (x and y) directions to check its ideal tensile strength. The calculated stress-strain relations of monolayer MoSi 2 N 4 are illustrated in Fig.…”

“…The moderate band gap, high mobility, and excellent stability of monolayer MoSi 2 N 4 promise its advantages in nano-electronic and optoelectronics. Since the experimental synthesis of layered MoSi 2 N 4 , an enormous amount of research efforts have been devoted to exploring its various properties [17][18][19][20][21][22][23][24][25][26][27]. Density functional theory (DFT) calculations indicated that monolayer MoSi 2 N 4 has a larger Poisson's ratio (0.28) [17] than that of graphene (0.16) [28].…”

“…Since the experimental synthesis of layered MoSi 2 N 4 , an enormous amount of research efforts have been devoted to exploring its various properties [17][18][19][20][21][22][23][24][25][26][27]. Density functional theory (DFT) calculations indicated that monolayer MoSi 2 N 4 has a larger Poisson's ratio (0.28) [17] than that of graphene (0.16) [28]. Guo et al investigated the effects of biaxial strain on electronic, transport, and piezoelectric properties of monolayer MoSi 2 N 4 [20].…”

Structure effect on intrinsic piezoelectricity in septuple-atomic-layer $\mathrm{MSi_2N_4}$ (M=Mo and W)

“…The valley-dependent properties of monolayer MoSi 2 N 4 , WSi 2 N 4 and MoSi 2 As 4 have been investigated by the first-principle calculations 24 . The structural, mechanical, thermal, electronic, optical and photocatalytic properties of MoSi 2 N 4 are studied by using hybrid density functional theory (HSE06-DFT) 25 .…”

Semiconductor-to-metal transition in bilayer MoSi$_2$N$_4$ and WSi$_2$N$_4$ with strain and electric field

“…30 With higher carrier mobility than MoS 2 and better air-stability than phosphorene, MoSi 2 N 4 and its family structure of MA 2 Z 4 monolayers (M represents an early transition metal, A is Si or Ge, Z stands for N, P or As) have soon received much attention. [31][32][33][34][35][36][37][38][39][40][41][42] Nevertheless, there is still lack of band gap engineering study of bilayer MoSi 2 N 4 and WSi 2 N 4 , which is critical for the future application of layered MA 2 Z 4 material in nanoa) Electronic mail: qingyun wu@sutd.edu.sg b) Electronic mail: ricky ang@sutd.edu.sg electronics and optoelectronic devices up to date.…”