Hydrogen production from H2S on metal-doped FeS Mackinawite monolayer via DFT calculations

The utilization of H2S resulting in the production of hydrogen and sulfur is a challenging task, but this process would lead to an environmentally friendly energy source. The decomposition of H2S by heterogeneous catalysis seems to be the most preferable way, and two-dimensional nanostructures are considered promising materials due to the large contact surface with the reagent in such reactions. An option of cyclic functionalization of metal sulfides (iron sulfides, particularly), attracts special attention from the experts. Using the evolutionary algorithm realized in the USPEX program, we showed that the FeS monolayer with a square lattice is the lowest energy structure among other 2D structures in Fe-S system, and the metastable states near the convex line represent the same structure with defects, which makes such a structure an example of a Berthollide compound. The doping with molybdenum (tungsten) atoms decrease the barriers values of limiting stages to 1.06 eV (1.05 eV) and 0.91 eV (1.15 eV) for the first and the second stages of hydrogen cleavage from H2S molecule, respectively. This opens prospects for the use of transition metal sulfides in low-dimensional structures in heterogeneous catalytic production of hydrogen from associated H2S gas.