Fig. 8 Calculated free-energy diagram of hydrogen evolution on
(a) pure surface, (b) Pt@La and Pt@Ta, (c) Ru@La and Ru@Ta, and (d)
Ni@La and Ni@Ta. Varied relaxed structures and the corresponding values
of ΔG H are attached. Coloring scheme: green (La),
light blue (Ta), red (O), blue (N), grey (Pt), purple (Ru), orange (Ni)
and white (H).