Fig. 4. The optimized configurations of Li/WS2 with different numbers of H2 molecules. (a) Top view of 1H2/Li/WS2, (b) Top view of 2H2/Li/WS2, (c)Top view of 3H2/Li/WS2, (d) Side view of 1H2/Li/WS2 (e) Side view of 2H2/Li/WS2 (f) Side view of 3H2/Li/WS2. The silvery grey and yellow balls in this Amprenavir figure and figures below are Li and hydrogen atoms, respectively. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)Figure optionsDownload full-size imageDownload high-quality image (276 K)Download as PowerPoint slide
To increase the available surface area for hydrogen storage, we now turn to consider the double-sided adsorption structures. On the basis of the above results about the single Li atom decorated WS2, there are three possible adsorption sites (T1, T2, H) on the opposite side of the WS2 layer as shown in Fig. 1(a). According to our results, the second Li atom also prefers to be on the T2 site of the opposite side of WS2. Thus the preferable configuration is shown in Fig. 5(a and b) with the two Li atoms located on both sides of WS2. The average binding energy of the Li atom is slightly enhanced to 2.03 eV (GGA: 1.72 eV) compared to the value of 1.77 eV (GGA: 1.50 eV) for the case of a single Li atom adsorption, suggesting that Li atom can disperse stably on the WS2 surface.