Polarization Electric Field in 2D Polar Monolayer Silicon Monochalcogenides SiX (X = S, Se) as Potential Photocatalysts for Water Splitting

The polarization electric field generated by the dipole moment can swiftly separate photogenerated carriers. Herein, the first‐principles calculations to study the structural, electronic, polarization electric field, optical, and photocatalytic properties of 2D polar monolayer silicon monochalcogenide SiX (X = S, Se) are studied. The polarization electric field induced by a noncentrosymmetric structure is a direction from the X (X = S, Se) atomic surface to the Si atomic surface. The polar monolayer SiS (SiSe) is an indirect semiconductor with a bandgap of 2.997 eV (2.903 eV). The absorption coefficients of the polar monolayer SiX (X = S, Se) reach the order of 105 cm−1, and the absorption onset can be extended to the visible light region. The band alignment of the 2D polar monolayer SiX (X = S, Se) is suitable for photocatalytic water splitting. The obtained results show that the 2D polar monolayer SiX (X = S, Se) with a polarization electric field is a potential catalyst for photocatalytic water splitting. Polar photocatalysts that have a dipole moment‐induced polarization electric field may be favorable for the rapid separation of photogenerated carriers. The 2D polar monolayer SiX (X = S, Se) with a polarization electric field induced by a noncentrosymmetric structure is a potential catalyst for photocatalytic water splitting.