Strain Effect on the Dissociation of Water Molecules on Silicene: Density Functional Theory Study

Abstract

Dissociative adsorption of water molecules on silicene is an efficient way to open the band gap of silicene for electronic applications. However, the dissociation of H 2 O molecules on silicene is difficult due to the Pauli exclusion effect between H 2 O molecules and silicene. By using density functional theory calculations, we investigated the effect of strain on the dissociative barrier of H 2 O molecules on silicene. Our results demonstrate that the tensile strain can significantly reduce the dissociative energy barrier of H 2 O molecules on silicene, whereas the compressive strain has slight effect on the dissociation barrier. In addition, the dissociation barrier reduces from 0.85 to 0.27 eV with the tensile strain of 9%, where the reaction time for the dissociation of H 2 O on silicene can be reduced significantly from 2.23 × 10 2 to 3.60 × 10 −8 s. The mechanism for the effect of strains on the depressed dissociation barrier of H 2 O molecules on silicene can be understood through analyzing the density of states and orbital charge of the water/silicene system. The band gap of silicene is 0.37 eV after the dissociation of H 2 O molecules, and the carrier mobility is relatively high, which is important for its applications in logic circuits. Further study indicates that the dissociation of H 2 O is favorite at atomic vacancy and grain boundary of silicene with and without strain.

A Theoretical Analysis on the Oxidation and Water Dissociation Resistance on Group‐IV Phosphide Monolayers

“…The dissociation pathways and energy barriers as well as heat of reaction from the LST/QST and NEB calculations are displayed in Figure 6. It is worth noting that the dissociation pathways of H 2 O molecules on the MP monolayers are similar to that on the silicene, which possesses a high energy barrier and exhibits excellent stability in the water environment [32] . The H 2 O molecule undergoes a transition from physisorption to chemisorption by overcoming energy barriers of 2.61 eV, 1.76 eV, 1.55 eV and 1.34 eV on the CP, SiP, GeP and SnP monolayers, respectively.…”

“…It is worth noting that the dissociation pathways of H 2 O molecules on the MP monolayers are similar to that on the silicene, which possesses a high energy barrier and exhibits excellent stability in the water environment. [32] The H 2 O molecule undergoes a transition from physisorption to chemisorption by overcoming energy barriers of 2.61 eV, 1.76 eV, 1.55 eV and 1.34 eV on the CP, SiP, GeP and SnP monolayers, respectively. It should be pointed out that the energy barrier decreases steadily from CP to SnP and this is mainly because the buckling distance between the phosphorus sublayer and group-IV sublayer increases with increasing atomic number, as can be concluded from Table 1, leading to a corresponding increase in dipole moment and a decrease in the strength of hybrid orbital.…”

“…Moreover, all the H 2 O dissociation barriers are larger than 0.75 eV, even larger than the value (0.85 eV) on the stable silicene, indicating the dissociation reactions are kinetically difficult to happen on the MP monolayers at room temperature. [32,34] From the thermodynamic point of view, the reaction enthalpy for the MP monolayers is obtained and has a value of 0.92-2.05 eV, indicating the thermodynamic stability of the MP monolayers in the water environment.…”

Two‐Dimensional Silicon for (Photo)Catalysis

“…[ 43 ] However, another work stated that the tensile strain could significantly reduce the dissociative energy barrier of H 2 O molecules on silicene, whereas the compressive strain had a slight effect on the dissociation barrier. [ 44 ] The photocatalytic water‐splitting performance could be improved by designing and constructing the 2D Si‐based complex. Wang et al studied the influence of the doping amount on the catalytic water‐splitting performance for fluorine‐doped monolayer silicane.…”

Mechanism of the two-dimensional WSeTe/Zr2CO2 direct Z-scheme van der Waals heterojunction as a photocatalyst for water splitting

“…Furthermore, it is important to precisely control the electronic structure of 2D heterojunction, tuned by in-plane biaxial strain. [43][44][45] Therefore, herein, different biaxial strains were applied to the constructed WSeTe/Zr 2 CO 2 heterostructure by compression and tension. We define the biaxial strain as follows: e = DL/L, where DL denotes the deformation and L denotes the equilibrium lattice constant.…”