Two-dimensional alloying MNS4 (M, N = Mn, Fe, Co, Ni, Pd) materials with pentagonal pucker for highly efficient electrocatalytic hydrogen reaction

The rational design of the excellent catalytic activity electrocatalyst to replace noble metal is the core of hydrogen production from water electrolysis. Herein, we designed and demonstrated two-dimensional(2D) alloying monolayer MNS4 (M, N = Mn, Fe, Co, Ni, Pd) materials with three types of pentagonal puckers. Our results showed that the Fe-sites are better than the Co-, Ni-and Pd-sites, so the earth-abundant penta-FeS2 material is expected to be well applied in the HER catalyst. The method of alloying can improve not only the catalytic activity at the metal sites, but also the sulfur sites with abundant adsorption sites for alpha-type penta-MNS4 materials. Especially for the sulfur sites for alpha-FeCoS4 materials, there are the most excellent oGH* (0.02 eV) and outstanding exchange current density (-1.62 A/cm2) among all of the materials. We further showed that the alpha-type penta-MNS4 has a wide range of excellent d-band center (epsilon d), which corresponds to the better oGH*. Ulteriorly, we demonstrated that the reaction barrier of alpha-FeCoS4 is reduced by the method of alloying. Our results provide theoretical guidance for designing a novel and efficient HER electrocatalyst of pentagonal transition metal dichalcogenide.