Spin Polarization of 2D Weyl Semimetal Fe2Sn Enabling High Hydrogen Evolution Reaction Activity

It is well known that magnetic field is one of the effective tools to improve the activity of hydrogen evolution reaction (HER), but considering the inconvenient application of an external magnetic field, it is essential to find a ferromagnetic material with high HER activity itself. Fortunately, recent study has shown that the two‐dimmention (2D) Fe2Sn monolayer is a stable ferromagnetic topological Weyl semimetal material with high Tc of 433 K. Here, we report the Fe2Sn monolayer can be used as an alternative HER catalyst compared with expensive platinum (Pt). Our first‐principles results show that the Gibbs free energy (ΔGH*) value of the spin polarized Fe2Sn monolayer is −0.06 eV, much better than that without considering spin polarization (−1.23 eV). Moreover, the kinetic analysis demonstrates that the HER occurs on the Fe2Sn monolayer according to the Volmer‐Tafel mechanism with low energy barriers. Hence, our findings provide obvious evidence for spin‐polarization‐improved HER activity, paving a new way to design high‐performance HER catalysts. Spin polarization: We investigate the hydrogen evolution reaction activity (HER) activity of basal plane of the 2D ferromagnetic Weyl semimetal Fe2Sn. Our findings show that the Fe2Sn monolayer in spin polarized state exhibit superior HER performance when compared with that in spin un‐polarized, indicating that spin polarization enables high HER activity.