Effects of van der Waals interaction on the adsorption of H2 on MoS2 monolayers and nanoribbons

Density-functional theory calculations are performed to investigate the adsorption of molecular hydrogen onto MoS2 monolayers, armchair nanoribbons, and stacked monolayer-armchair nanoribbon complexes. The van der Waals interaction is explicitly included through the use of three distinct exchange-correlation functionals and a comparison with the use of LDA is made. The adsorption energy, structural properties, band structure are dis-cussed, considering different adsorption sites, nanoribbon dimensions, and H2 concentrations. Recovery time is evaluated for a particular situation where significant adsorption energy is obtained for the monolayer plus nanoribbon complex,-together with a reasonable modification of the electronic structure, in comparison with MoS2 monolayer and free-standing nanoribbons-, pointing at a promising use of this system as a molecular hydrogen sensor.