TY - JOUR

T1 - Silicon diphosphide (SiP2) and silicon diarsenide (SiAs2)

T2 - Novel stable 2D semiconductors with high carrier mobilities, promising for water splitting photocatalysts

AU - Shojaei, Fazel

AU - Mortazavi, Bohayra

AU - Zhuang, Xiaoying

AU - Azizi, Maryam

N1 - Funding Information: This work is partially supported by Institute for Research in Fundamental Sciences (IPM) , Tehran, Iran and the Iran Science Elites Federation. B. M. and X. Z. appreciate the funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy within the Cluster of Excellence PhoenixD (EXC 2122, Project ID 390833453).

PY - 2020/6

Y1 - 2020/6

N2 - Two dimensional (2D) semiconducting light absorbers, have recently considered as promising components to improve the efficiency in the photocatalytic hydrogen production via water splitting. In this work, by employing density functional theory computations, we introduced novel SiX2 (X = P, As) nanosheets in tetragonal (penta-) and orthorhombic (rec-) phases, as promising light absorber semiconductors for overall water splitting. The predicted nanomembranes exhibit good mechanical, dynamical and thermal stabilities. They also show small cleavage energies in the range of 0.31 J/m2 to 0.39 J/m2, comparable to that of the graphene and thus suggesting the feasibility of their experimental exfoliation. Notably, predicted monolayers are semiconductors with indirect band gaps of 2.65 eV for penta-SiP2, 2.35 eV for penta-SiAs2, 1.89 eV for rec-SiAs2, and a direct band gap of 2.21 eV for rec-SiP2. These nanomaterials however show relatively large interlayer quantum confinement effects, resulting in smaller band gap values for bilayer lattices. We observed a huge difference between the electron and hole mobilities for penta-SiP2 and rec-SiAs2 monolayers and highly directional dependent electron and hole mobilities in rec-SiP2, yielding an effective separation of photogenerated charge carriers. Remarkably, these novel nanomembranes show strong absorption in the visible region of light as well as suitable band edge positions for photocatalytic water splitting reaction, specifically under neutral conditions.

AB - Two dimensional (2D) semiconducting light absorbers, have recently considered as promising components to improve the efficiency in the photocatalytic hydrogen production via water splitting. In this work, by employing density functional theory computations, we introduced novel SiX2 (X = P, As) nanosheets in tetragonal (penta-) and orthorhombic (rec-) phases, as promising light absorber semiconductors for overall water splitting. The predicted nanomembranes exhibit good mechanical, dynamical and thermal stabilities. They also show small cleavage energies in the range of 0.31 J/m2 to 0.39 J/m2, comparable to that of the graphene and thus suggesting the feasibility of their experimental exfoliation. Notably, predicted monolayers are semiconductors with indirect band gaps of 2.65 eV for penta-SiP2, 2.35 eV for penta-SiAs2, 1.89 eV for rec-SiAs2, and a direct band gap of 2.21 eV for rec-SiP2. These nanomaterials however show relatively large interlayer quantum confinement effects, resulting in smaller band gap values for bilayer lattices. We observed a huge difference between the electron and hole mobilities for penta-SiP2 and rec-SiAs2 monolayers and highly directional dependent electron and hole mobilities in rec-SiP2, yielding an effective separation of photogenerated charge carriers. Remarkably, these novel nanomembranes show strong absorption in the visible region of light as well as suitable band edge positions for photocatalytic water splitting reaction, specifically under neutral conditions.

KW - 2D materials

KW - Carrier mobility

KW - IV-V compounds

KW - Photocatalysis

UR - http://www.scopus.com/inward/record.url?scp=85078307844&partnerID=8YFLogxK

U2 - 10.1016/j.mtener.2019.100377

DO - 10.1016/j.mtener.2019.100377

M3 - Article

AN - SCOPUS:85078307844

VL - 16

JO - Materials Today Energy

JF - Materials Today Energy

M1 - 100377

ER -