GeN₃ monolayer: A promising 2D high-efficiency photo- hydrolytic catalyst with High carrier mobility transport anisotropy

The investigations of two-dimensional photocatalysts are promising subjects in clean and renewable energy. Herein, we proposed a novel two-dimensional GeN₃ monolayer. The stability of GeN₃ monolayer was examined via formation energy, phonon calculations and ab initio molecular dynamics simulations. Excellent photocatalytic properties are revealed: (a) GeN₃ monolayer is a semiconductor with appropriate band gap of 1.962 eV that the valence and conduction bands straddle the redox potential of water. (b) GeN₃ monolayer has extremely high carrier mobility with anisotropic character (its electron mobility is 1.55 × 10⁴ cm² V⁻¹ s⁻¹ along the armchair direction, whereas the hole mobility reaches 1.6 × 10³ cm² V⁻¹ s⁻¹ along the zigzag direction), which boost the separation of electron-hole pairs. (c) The GeN₃ monolayer shows strong light absorption coefficients (up to 10⁵ cm⁻¹) in the visible regions, leading to high solar-to-hydrogen efficiency (12.63 %). (d) Furthermore, the band gap of the GeN₃ monolayer could be engineered from indirect to direct under external strain and electric field. This work discloses a novel 2D GeN₃ monolayer whose fascinating properties make it a promising photocatalyst for hydrolyzing to produce hydrogen.