Experimental and theoretical investigation of the cycle durability against CO and degradation mechanism of the LaNi5 hydrogen storage alloy

From both the experimental and theoretical aspects we have investigated the cycle durability against CO and degradation mechanism of the LaNi5 hydrogen storage alloy with CO-containing H2. Temperature-programmed desorption (TPD) measurements on the pristine alloy and the corresponding one after hydrogen absorption–desorption cycles exhibit that: (1) the molecular CO can be adsorbed on the clean alloy surface, and thus decrease the hydrogen storage ability of the alloy; (2) with the increase of the cycle number the partial decomposition of the CO and the subsequent adsorption of C atom and O atom on the surface is deleterious to the hydrogen storage competence of alloy. From the results of first-principle calculations, it is found that the adsorption of the molecular CO prefers the on-top and bridging sites on the Ni atoms. Moreover, the latter one is more stable than the former one.