A First-Principles Study of Nonlinear Elastic Behavior and Anisotropic Electronic Properties of Two-Dimensional HfS2

Abstract

We utilize first principles calculations to investigate the mechanical properties and strain-dependent electronic band structure of the hexagonal phase of two dimensional (2D) HfS2. We apply three different deformation modes within −10% to 30% range of two uniaxial (D1, D2) and one biaxial (D3) strains along x, y, and x-y directions, respectively. The harmonic regions are identified in each deformation mode. The ultimate stress for D1, D2, and D3 deformations is obtained as 0.037, 0.038 and 0.044 (eV/Ang3), respectively. Additionally, the ultimate strain for D1, D2, and D3 deformation is obtained as 17.2, 17.51, and 21.17 (eV/Ang3), respectively. In the next step, we determine the second-, third-, and fourth-order elastic constants and the electronic properties of both unstrained and strained HfS2 monolayers are investigated. Our findings reveal that the unstrained HfS2 monolayer is a semiconductor with an indirect bandgap of 1.12 eV. We then tune the bandgap of HfS2 with strain engineering. Our findings reveal how to tune and control the electronic properties of HfS2 monolayer with strain engineering, and make it a potential candidate for a wide range of applications including photovoltaics, electronics and optoelectronics.

Z-Scheme photocatalytic solar-energy-to-hydrogen conversion driven by the HfS2/SiSe heterostructure

“…The rectangular supercells of the HfS 2 and SiSe monolayers were used to investigate the anisotropic performance. The presently optimized lattice constants of the HfS 2 monolayer (a = 6.21, b = 3.59 Å) and the SiSe monolayer (a = 5.98, b = 3.47 Å) are consistent with those that had been previously reported, [37][38][39]42,43,54 shown in Table S1 (ESI †). Therefore, the mismatch ratio of the HfS 2 and SiSe heterostructures is approximately 4%.…”

“…The anisotropic electronic properties and nonlinear elastic behavior of the HfS 2 monolayer were explored using the first-principle calculations. 37 The effects of the vertical strain on the electronic and optical properties were investigated by Hoat et al 38 The enhanced effects of the intrinsic structural defects on the thermoelectric and optoelectronic properties are also reported for the HfS 2 monolayer. 39 Opoku et al 40 reported that the conduction band minimum (CBM) of HfS 2 matches the reduction potential for H + /H, but Wang et al 41 gave the opposite conclusion.…”

Improved Thermoelectric Performance of Monolayer HfS2 by Strain Engineering

“…Table shows the stable crystal structure of monolayer HfS 2 , which can be observed to be in good agreement with the theoretical results in previous reports in the literature ,− and proves the reliability of our calculations. Furthermore, the stability of the structure is verified by calculating the phonon dispersion without an imaginary frequency (Figure a).…”

Research progress of transition-metal dichalcogenides for the hydrogen evolution reaction

“…142 HfS 2 nanosheets can withstand large ultimate strains in D1, D2 and D3 (that is, the three directions of x, y, and x-y). 143 The other materials in the TMD family, such as WS 2 , NiTe 2 , MoSe 2 , WSe 2 etc., are also known for their high mechanical stability. 141 All of this indicates the great potential of strain engineering to regulate the HER activities of TMDs.…”