A theoretical investigation of transition metal doping-engineered MoSi2N4 2 N 4 materials as highly efficient photocatalysts for water splitting

Photocatalytic water splitting is a cheap, clean and attractive hydrogen production method. In this study, using first-principles calculations, we design and demonstrate two-dimensional (2D) transition metal-doped MoSi2N4 2 N 4 (TM-MoSi2N4, 2 N 4 , TM = Ge, Sn, W) materials as high-performance photocatalyst, which has high carrier mobility, optical absorption properties and solar-to-hydrogen (STH) efficiency. MoSi2N4 2 N 4 was successfully synthesized experimentally [Hong et al., Science, 2020] and our results affirms the good stability of TM-MoSi2N4 2 N 4 materials. Furthermore, we aim to demonstrate appropriate band alignment that facilitates the redox potential required for water splitting, enables efficient charge separation of photogenerated electron-hole pairs, promotes effective optical absorption, and supports high solar-to-hydrogen (STH) conversion efficiency. Last but not least, we reveal that the TM heteroatom doping can enhance the photocatalytic activity towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Especially, the Sn-MoSi2N4 2 N 4 material provides an optimal hydrogen adsorption Gibbs free energy (Delta GH*) Delta G H* ) value of- 0.02eV. Our work suggests that TM-MoSi2N4 2 N 4 materials are superior photocatalysts for water splitting, which can be employed with low cost and high performance.