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 discussed, 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. © 2022