Theoretical modelling of porous silicon decorated with metal atoms for hydrogen storage

• Published in: International journal of hydrogen energy 2020-10, Vol.45 (49), p.26321-26333
• Main Authors: González, Israel, De Santiago, Francisco, Arellano, Lucía G., Miranda, Álvaro, Trejo, Alejandro, Salazar, Fernando, Cruz-Irisson, Miguel
• Format: Article
• Language: English
• Subjects: Beryllium; DFT; Hydrogen storage; Lithium; Palladium; Porous silicon
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2020.05.097

There is experimental evidence suggesting that metal adatoms enhance the physisorption of hydrogen molecules in porous silicon. However, theoretical reports about the physical properties for this material to be suitable for hydrogen storage are scarce. Thus, in this work we employ Density Functional Theory to study the effects of decoration with metals on the hydrogen-adsorption properties on hydrogen-passivated porous silicon. The results indicate that lithium and palladium decorating atoms are strongly bonded to the porous silicon—preventing the adverse effects of clusterization—while beryllium is not. Lithium and palladium exhibit physisorption capacity up to 5 and 4 hydrogen molecules per adatom, respectively. In contrast, adsorption of hydrogen molecules in beryllium is too weak as the adatom is not chemisorbed on the surface of the pore. The hydrogen passivation of the pore surface proves to be beneficial for a strong chemisorption of the decorating atoms. [Display omitted] •Passivating H atoms are essential for the strong chemisorption of Li and Pd.•Li and Pd act as active sites for the adsorption of H2 molecules.•Li is able to absorb the maximum amount of five H2 molecules.•Be does not adsorb H2 molecules because it was not chemisorbed to porous silicon.•Decorated porous silicon could be an attractive hydrogen storage material.