Point defects in VS2 monolayer towards NH3 synthesis

Ammonia is essential raw material for producing fertilizers, plastics and dynamites. The traditional Haber-Bosch process for ammonia production is hindered by high demand for energy and heavy pollution. Defective transition metal dichalcogenides have been comprehensively investigated for catalyzing some hydrogenation reactions. However, less attention was paid to ammonia synthesis. In this work, the catalysis performance of point defects in VS2 monolayer was evaluated using the density functional theory. The S vacancy in 1H-VS2 has good activity for electrocatalysis of synthesizing ammonia. For gas phase N2, the potential-determining step (PDS) is found to be 0.538 eV at S vacancy. The V adatom defect is more attractive to N2 molecule with a slightly higher PDS. A water solution environment has minor effect on the PDS for S vacancy. But the N2 adsorption energy on the V adatom is reduced. Low formation energies and high catalysis activity make the defective VS2 a very promising catalyst in ammonia production