Dual-functional 2D ferromagnetic material Fe2C12: Synergistic integration of hydrogen evolution reaction and hydrogen storage

Abstract

Addressing the dual challenges of efficient hydrogen production and storage is critical for the realization of a hydrogen economy. This study employs density functional theory to investigate the dual-functional capabilities of the two-dimensional ferromagnetic material 2D-Fe2C12 for hydrogen evolution reaction (HER) catalysis and high-density hydrogen storage. For HER, 2D-Fe2C12 exhibits a near-optimal Gibbs free energy change (ΔGH*= 0.07 eV), surpassing the benchmark Pt(111) catalyst. Kinetic analysis via climbing-image nudged elastic band simulations reveals a dominant Volmer–Tafel pathway, with the Tafel mechanism as the rate-determining step and exhibiting a barrier of 0.57 eV. In terms of hydrogen storage, 2D-Fe2C12 achieves a gravimetric capacity of 5.88 wt. %, exceeding the U.S. DOE 2025 target of 5.5 wt. %. The unit cell can adsorb eight H2 molecules through dual mechanisms: strong Kubas-type interactions (donation/back-donation) for the first six H2 molecules, and weak electrostatic binding for the remaining two. Thermodynamic stability analysis confirms practical operability, with the 8H2 complex being stabilized at ambient temperature (298.15 K) and moderate pressure (5.8 MPa). These results demonstrate that 2D-Fe2C12 can serve as a promising dual-functional platform for sustainable hydrogen technologies.