High stability and tunable hydrogen evolution material with defect-enhanced photocatalytic properties:penta-BAs5 monolayer

In this work, on the basis of first principles calculations, we theoretically predict a pentagonal structure material called penta-BAs5 and discuss the photocatalytic properties under its intrinsic and defective modes. Formation energy and phonon dispersion curve all proved its high stability. Penta-BAs5 has a 2.38 eV bandgap and has indirect bandgap semiconductor performance. Surprisingly, by analyzing the band edge distribution, the Gibbs free energy changes (Delta G), and applying strain, it is found that penta-BAs5 can spontaneously proceed the hydrogen evolution reaction (HER) can under neutral and acidic conditions. Interestingly, after applying electric field in the range of 0-0.8 eV/angstrom, the band edge alignment can keep stable. Intriguingly, the hydrogen evolution capacity of penta-BAs5 was greatly improved when the defects were present. Our study predicted a new two-dimensional pentagonal binary compound, broadened the field of the pentagonal structure families, and identified its application prospects in photocatalysis.