High-Throughput Calculations of Two-Dimensional Auxetic M₄X₈ (M = Transition Metals, X = Halogens) with Magnetism, Electrocatalysis, and Alkali Metal Battery Applications

Two-dimensional (2D) materials with multifunctional properties, such as negative Poisson's ratio (NPR), magnetism, catalysis, and energy storage capabilities, are of significant interest for advanced applications in flexible electronics, spintronics, catalysis, and lithium-ion batteries. However, the discovery of such materials in low-dimensional limit, remains a challenge. We perform high-throughput density-functional theory (DFT) calculations to explore a new class of 2D V-shaped monolayers with remarkable physicochemical properties. Among 17 stable M₄X₈ (M = transition metal; X = halogen) compounds, we identify 10 auxetic monolayers, with Pd₄I₈ standing out for its high NPR of -0.798. Notably, 2 of these materials exhibit half-semiconductor properties, while 4 others are bipolar magnetic semiconductors. Additionally, these materials demonstrate promising catalytic activity for hydrogen and oxygen evolution reactions and show potential as anodes for rechargeable metal-ion batteries.