Room temperature ferromagnetic TiTe monolayer: a topological material for efficient hydrogen evolution reaction

Abstract Recently, two-dimensional (2D) half-topological states, emerging in 2D half Weyl semimetals and half Chern insulators, have attracted much attention due to their promising applications in spintronics. The fully spin-polarized topological nontrivial bands near the Fermi level give rise to spin-resolved bulk and boundary charge currents, which might be beneficial to the charge transfer in catalytic reactions. Taking the room temperature ferromagnetic (FM) TiTe monolayer ( T C ∼ 965 K) as an example, the hydrogen evolution reaction (HER) performance was studied by first-principles calculations. The Gibbs free energy ΔG H * of the hollow site surrounded by Ti atoms (hollow@Ti) is evaluated as −0.06 eV, approaching that of Pt (−0.09 eV). The corresponding activation energies of the Tafel and Heyrovsky reactions are estimated to be 0.92 and 1.32 eV, respectively, which are comparable to MoS 2 (1.0–1.5 eV). In addition, the calculation results indicate that ΔG H * is robust against the magnetization direction and is linearly related to the biaxial strain ranging from −3% to 3%. This work uncovers the efficient HER performance of room temperature FM TiTe monolayers, and provides new insights into the design of catalysts based on half Weyl semimetals and half Chern insulators.