A phosphorene-like InP3 monolayer: structure, stability, and catalytic properties toward the hydrogen evolution reaction

Abstract

Exploring a new phase of two-dimensional (2D) materials with novel electronic and catalytic properties is of particular importance for both fundamental research and practical applications in clean energy. Herein, we report a new phase of the InP₃ monolayer with a phosphorene-like structure for the hydrogen evolution reaction on the basis of density functional theory calculations. Our results demonstrate that 2D phosphorene-like InP₃ (P-InP₃) can be obtained by exfoliating the (0−1 1) surface of the InP₃ bulk with a cleavage energy of 1.08–1.37 J m⁻², which is more stable energetically than the 2D graphene-like InP₃ (G-InP₃) monolayer by −0.17 eV per atom. The P-InP₃ monolayer is a semiconductor with a direct band gap of 0.53 eV and anisotropic carrier mobility, while its bilayer and trilayer are metallic. In particular, the P-InP₃ monolayer, bilayer and trilayer show high catalytic activity toward the hydrogen evolution reaction (HER) comparable to Pt and 1T′-MoS₂ on the basis of the calculated Gibbs free energy. Besides, the G-InP₃ bilayer and trilayer also exhibit similar catalytic activity. The calculation of the microkinetic process of the HER indicates that both Volmer–Tafel and Volmer–Heyrovsky reactions are possible, but the latter one is more feasible for both P-InP₃ and G-InP₃. The P-InP₃ monolayer is structurally dynamically stable, confirmed with the calculated phonon spectrum and Born–Oppenheimer molecular dynamics simulation in an aqueous environment at 300 K. These findings imply the great potential of the 2D P-InP₃ monolayer in electronics, optoelectronics, and catalytic HER.