Hittorf's violet phosphorene as a promising candidate for optoelectronic and photocatalytic applications: first-principles characterization

Abstract

Utilizing density functional theory, we investigate the structural stabilities, electronic structures, and optical properties of monolayer violet phosphorene, i.e., Hittorfene, under an external vertical electric field and upon in-layer biaxial strain control. We find that compared with monolayer black phosphorene, monolayer violet phosphorene has a significantly larger direct band gap of 2.50 eV, and it is sensitive to an external vertical electric field, under which it undergoes an intriguing direct-indirect and insulator-metal transition. By applying an in-layer biaxial strain, the semiconductor characteristic of monolayer violet phosphorene is found to be robust and stable over a wide range of strains (-10 to 10%), with a minimum bulk gap still being up to 0.90 eV at a tensile strain of 10%. This demonstrates that the band edges of monolayer violet phosphorene not only can straddle water redox potentials in the equilibrium state but can also be available within the strain range of -7 to 7% for facilitating photocatalytic water splitting. In particular, the suitable band edges and intensive absorption of visible light suggest that a strain ratio of -7% would be the more favorable condition for water splitting under visible light.

Simulated Raman spectra of bulk and low-dimensional phosphorus allotropes

“…Interestingly, the calculated energy gap found for single-layer Hittorf's P (1.70eV) is much wider compared to its black counterpart (0.89eV). These resulting values are quite close to those reported in literature 46,54 , as described in Table S2 reported in Section 1 of Supplementary Information. The direct character of the band gap has been double-checked using the Grimme D3 version and we found no changes.…”

Enhanced photocatalytic properties of a chemically modified blue phosphorene

“…[32][33][34][35] Following the fact nding journey, many other allotropes/ polytypes of phosphorene viz., red, black, violet, green phosphorene have been realized [36][37][38][39] and some of them have been explored for water splitting application. [40][41][42][43] More recently, a new member of phosphorene polytype was realized through the synthesis of mono-layered honeycomb buckled bluephosphorene (B-phosphorene) on an Au (111) sheet using a molecular beam epitaxial method with black-phosphorous as precursor. 44 It has been reported that a specic dislocation in black phosphorene induces a new structure with zigzag puckering, called B-phosphorene with a characteristic tunable bandgap upto 2 eV.…”

Structure and Properties of Violet Phosphorus and Its Phosphorene Exfoliation

“…It was even debated as to whether violet phosphorus was even a stable allotrope or a metastable intermediate from red to black phosphorus. [10] Violet phosphorene, a promising semiconducting 2D material for photonic and electronic applications, [11] stays unexplored owing to the uncertainty of its bulk structures. The properties of both bulk and layered violet phosphorus are unexplored, which hinders their further applications.…”