In Situ/Operando Capturing Unusual Ir<sup>6+</sup> Facilitating Ultrafast Electrocatalytic Water Oxidation
Lili Li, Hainan Sun, Zhiwei Hu, Jing Zhou, Yucheng Huang, Haoliang Huang, Sanzhao Song, Chih‐Wen Pao, Yu‐Chung Chang, A. C. Komarek, Hong‐Ji Lin, Chien‐Te Chen, Chung‐Li Dong, Jian‐Qiang Wang, Linjuan Zhang
Abstract
Abstract Identifying real active sites and understanding the mechanism of oxygen evolution reaction (OER) are still a big challenge today for developing efficient electrochemical catalysts in renewable energy technologies. Here, using a combined in situ/operando experiments and theory, the catalytic mechanism of the ordered OER active Co and Ir ions in Sr 2 CoIrO 6− δ is studied, which exhibits an unprecedented low overpotential 210 mV to achieve 10 mA cm –2 , ranking the highest performance among perovskite‐based solid‐state catalysts. Operando X‐ray absorption spectroscopies as a function of applied voltage indicates that Ir 4+ ion is gradually converted into extremely high‐valence Ir 5+/6+ , while the part of Co 3+ ion is transferred into Co 4+ under OER process. Density functional theory calculations explicitly reveal the order Co‐O‐Ir network as an origin of ultrahigh OER activity. The work opens a promising path to overcome the sluggish kinetics of OER bottleneck for water splitting via proper arrangements of the multi‐active sites in catalyst.