Sustainable water oxidation enabled by a complex-doped cobalt oxide electrode
Hongsheng Wang, Jia Lei, Jiashun Wu, Yan Shi, Yunze Zhang, M. Wang, Hao Fei, Siyuan Wang, Ziyi Wang, Ruoqi Liu, Ruoqi Liu, Ting Shan Chan, Shu-Chih Haw, Cheng‐Wei Kao, Aleksandra Wanda BARON-WIECHEĆ, Changfeng Yan, Hui Kong, Zhenbin Wang, Fu-rong Chen, Zhenbin Wang, Fu-rong Chen, Jian Wang
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 LiCoO2, a cobalt oxide that can be sourced from spent lithium-ion batteries, for sustainable water oxidation. Specifically, by co-doping LiCoO2 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 LiCo0.79Ni0.1Fe0.1Pd0.01O2 achieves a competitive water oxidation stability of over 2000 hours. Additionally, in membrane electrolyzer tests, LiCo0.79Ni0.1Fe0.1Pd0.01O2 outperforms the benchmark RuO2, delivering 2.5 A cm−2 at 1.58 V and maintaining stability for over 1400 hours. By elucidating the role of each dopant in LiCo0.79Ni0.1Fe0.1Pd0.01O2, this work offers critical insights for the rational design of sustainable water splitting electrodes. The development of sustainable water oxidation catalysts is crucial for hydrogen production, yet cobalt-based materials often suffer from instability. Here, the authors report that co-doping LiCoO2 with nickel, iron, and palladium yields a durable electrode with stability of over 2,000 hours.