Sustainable water oxidation enabled by a complex-doped cobalt oxide electrode.

Wang, Hongsheng; Lei, Jia; Wu, Jiashun; Shi, Yan; Zhang, Yunze; Wang, Miao; Fei, Hao; Wang, Siyuan et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Achieving sustainable water oxidation presents significant challenges, particularly employing cobalt-based electrocatalysts. Despite promising activities, many cobalt-based electrocatalysts undergo in-situ partial restructuring into disordered (oxy)hydroxides, as indicated by the Pourbaix diagram. This restructuring typically degrades structural integrity and electronic conductivity, undermining catalytic stability. Here, we propose a complex doping strategy to stabilize LiCoO<sub>2</sub>, a cobalt oxide that can be sourced from spent lithium-ion batteries, for sustainable water oxidation. Specifically, by co-doping LiCoO<sub>2</sub> with Ni, Fe, and Pd, we mitigate the reconstructed extent of the in-situ generated spinel phase during water oxidation reaction and enhance electrochemical stability. Furthermore, complex doping improves the surface conductivity and facilitates gas removal, boosting mechanical robustness. Consequently, the optimized LiCo<sub>0.79</sub>Ni<sub>0.1</sub>Fe<sub>0.1</sub>Pd<sub>0.01</sub>O<sub>2</sub> achieves a competitive water oxidation stability of over 2000 hours. Additionally, in membrane electrolyzer tests, LiCo<sub>0.79</sub>Ni<sub>0.1</sub>Fe<sub>0.1</sub>Pd<sub>0.01</sub>O<sub>2</sub> outperforms the benchmark RuO<sub>2</sub>, delivering 2.5 A cm<sup>-2</sup> at 1.58 V and maintaining stability for over 1400 hours. By elucidating the role of each dopant in LiCo<sub>0.79</sub>Ni<sub>0.1</sub>Fe<sub>0.1</sub>Pd<sub>0.01</sub>O<sub>2</sub>, this work offers critical insights for the rational design of sustainable water splitting electrodes.