Prediction of a multifunctional Mo 4 SiC monolayer material with intrinsic superconductivity, a giant negative Poisson's ratio, and promising hydrogen evolution reaction performance

Using a global structural prediction algorithm, we successfully designed a unique sandwich-like two-dimensional Mo4SiC material, consisting of two outer wrinkled Mo-Si layers and an inner planar central Mo-C layer. The predicted 2D Mo4SiC exhibits inherent superconductivity with a critical temperature (Tc) reaching 11.6 K. This Tc value is higher than that in the Mo2C monolayer. The superconductivity is found to mainly come from the low-frequency vibrations of the Mo atoms. Furthermore, Mo4SiC possesses a giant negative Poisson's ratio (NPR) of about -0.6, which ranks among the highest NPR values reported for two-dimensional materials. This unique mechanical property is found to result from its particular puckered hinge in the Si-Mo layers. Importantly, Mo4SiC can retain its NPR properties over a wide strain range, up to 20% strain. In addition, Mo4SiC exhibits a near-optimal hydrogen adsorption free energy ΔGH*, a key descriptor for promising hydrogen evolution reaction (HER) catalysis. This performance demonstrates that Mo4SiC may be a potential non-noble metal catalyst for catalytic applications. Our results highlight Mo4SiC as a multifunctional 2D material with significant potential for broad applications once successfully synthesised.