Two-Dimensional AuMX2 (M = Al, Ga, In; X = S, Se) Monolayers Featuring Intracrystalline Aurophilic Interactions with Novel Electronic and Optical Properties.

Aurophilicity, known as aurophilic interaction, is a strong attractive van der Waals interaction between cationic gold(I) centers, whose strength is comparable to the hydrogen bond. Here, we show that aurophilicity can serve as an engineering approach to expand the structural dimensionality for nanomaterials design. Specifically, based on a global-structure search method and density functional theory calculations, we predict a series of stable two-dimensional (2D) AuMX2 (M = Al, Ga, In; X = S, Se) structures featuring intracrystalline aurophilic interactions. All the AuMX2 monolayers designed are semiconductors with moderate band gaps, excellent carrier mobilities, and good optical properties. The intriguing chemistry of aurophilicity coupled with novel electronic properties render AuMX2 monolayers a potentially new series of 2D materials that are of fundamental importance in gold chemistry and of technological importance for nanoelectronics.