  Phosphorene has been attracted intense interest due to its unexpected high
carrier mobility and distinguished anisotropic optoelectronic and electronic
properties. In this work, we unraveled strain engineered phosphorene as a
photocatalyst in the application of water splitting hydrogen production based
on density functional theory calculations. Lattice dynamic calculations
demonstrated the stability for such kind of artificial materials under
different strains. The phosphorene lattice is unstable under compression
strains and could be crashed. Whereas, phosphorene lattice shows very good
stability under tensile strains. Further guarantee of the stability of
phosphorene in liquid water is studied by ab initio molecular dynamics
simulations. Tunable band gap from 1.54 eV at ambient condition to 1.82 eV
under tensile strains for phosphorene is evaluated using parameter-free hybrid
functional calculations. Appropriate band gaps and band edge alignments at
certain pH demonstrate the potential application of phosphorene as a
sufficiently efficient photocatalyst for visible light water splitting. We
found that the strained phosphorene exhibits significantly improved
photocatalytic properties under visible-light irradiation by calculating
optical absorption spectra. Negative splitting energy of absorbed H2O indicates
the water splitting on phosphorene is energy favorable both without and with
strains.
