The hydrogen adsorption on Zr-decorated LiB (001): A DFT study

The adsorption ability of H2 molecules on the Zr-decorated LiB (001) 2 × 2 surface is investigated using density functional theory. It was demonstrated that Zr atoms are preferentially adsorbed on the top of Li atom of the LiB surface. The formation of covalent bond of Zr-B and ionic bond of Zr-Li on the LiB surface leads to a stable Zr-decorated LiB surfaces for H2 adsorption. The Zr-decorated LiB (001) can adsorb up to four H2 molecules at ambient temperature and pressure with average adsorption energy in a range from −0.16 to −0.30 eV/H2, which is close to the target value specified by U.S. Department of Energy for commercial applications. On the basis of charge and bond population analysis, the projected density of states and the electron density distribution analysis, it was found that Zr atom acts as a bridge interacts with both H2 molecules and LiB surface atoms. The interaction between H2 and Zr-decorated LiB surface is weak chemisorptions. Furthermore, we show that two Zr atoms can be decorated on the LiB (001) 2 × 2 surface after considering the adsorption energy of Zr and minimum atomic distance between Zr atoms. Thus, the Zr-decorated LiB (001) can adsorb up to 8 H2 molecules indicating that Zr-decorated LiB (001) system might be a promising hydrogen storage material.