Such high activity was further quantified and compared by calculating the free energies of HER for different closed packed planes of GdTe, namely (100), (110), (111) and (211), found from the experimental XRD using Computational hydrogen electrode (CHE) model by Peterson et al. . Computed free energies of HER are compared in (Figure ). H* intermediate is most strongly adsorbed on the Gd atom in the terrace site of (211) plane, with adsorption energy of -1.03 eV where formation of H2 is highly endothermic and promotes poisoning of the surface.