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

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.