Lanthanide-regulating Ru-O covalency optimizes acidic oxygen evolution electrocatalysis
Lu Li1, Gengwei Zhang2, Chenhui Zhou1
1School of Materials Science and Engineering, Peking University, Beijing, China.
Abstract:
Precisely modulating the Ru-O covalency in RuOx for enhanced stability in proton exchange membrane water electrolysis is highly desired. However, transition metals with d-valence electrons, which were doped into or alloyed with RuOx, are inherently susceptible to the influence of coordination environment, making it challenging to modulate the Ru-O covalency in a precise and continuous manner. Here, we first deduce that the introduction of lanthanide with gradually changing electronic configurations can continuously modulate the Ru-O covalency owing to the shielding effect of 5s/5p orbitals. Theoretical calculations confirm that the durability of Ln-RuOx following a volcanic trend as a function of Ru-O covalency. Among various Ln-RuOx, Er-RuOx is identified as the optimal catalyst and possesses a stability 35.5 times higher than that of RuO2. Particularly, the Er-RuOx-based device requires only 1.837 V to reach 3 A cm-2 and shows a long-term stability at 500 mA cm-2 for 100 h with a degradation rate of mere 37 μV h-1.
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