Abstract

First-principles calculations have been used to investigate hydrogen adsorption on alkali atom dopedB36N36clusters. The alkali atom adsorption takes place near the six tetragonal bridge sites available onthe cage, thereby avoiding the notorious clustering problem. Adsorption of alkali atoms involves a chargetransfer process, creating positively charged alkali atoms and this polarizes the H2molecules thereby,increasing their binding energy. Li atom has been found to adsorb up to three hydrogen molecules withan average binding energy of 0.189 eV. The fully doped Li6B36N36cluster has been found to hold up to 18hydrogen molecules with the average binding energy of 0.146 eV. This corresponds to a gravimetric den-sity of hydrogen storage of 3.7 wt.%. Chemisorption on the Li6B36N36has been found to be an exothermicreaction, in which 60 hydrogen atoms chemisorbed with an average chemisorption energy of2.13 eV.Thus, the maximum hydrogen storage capacity of Li doped BN fullerene is 8.9 wt.% in which 60 hydrogenatoms were chemisorbed and 12 hydrogen molecules were adsorbed in molecular form.