“…Interestingly, some experimental studies reveal that hydrogen diffusion in GB of nickel is much faster than that in bulks due to a lower activation energy, 3,6 whereas the hydrogen diffusivity in GB of aluminum and nickel with ne grains is smaller than that in the bulks. 7,10,11,13 As to hydrogen diffusion in PdCu membranes, the reported experimental results are mainly concentrated on the polycrystalline phases, [19][20][21][22][24][25][26][27][28][29][30][31][32][33][34][35]37,39 while the theoretical investigations are all related to single crystals. 17,23,36,38,[40][41][42] It is therefore of importance to nd out the effect of GB on hydrogen diffusion of PdCu by means of rst principles calculation.…”