Iridium oxide nanoribbons with metastable monoclinic phase for highly efficient electrocatalytic oxygen evolution

• Published in: Nature communications Vol. 14; no. 1; pp. 1248 - 11
• Main Authors: Liao, Fan, Yin, Kui, Ji, Yujin, Zhu, Wenxiang, Fan, Zhenglong, Li, Youyong, Zhong, Jun, Shao, Mingwang, Kang, Zhenhui, Shao, Qi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04.03.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 140/146; 147/135; 147/143; 147/3; 639/301/299/886; 639/301/357/1015; 639/301/357/1016; 639/638/161/886; 639/925/357/1016; Catalysis; Catalysts; Catalytic activity; Density functional theory; Electrocatalysts; Energy consumption; Energy conversion; Evolution; Humanities and Social Sciences; Iridium; Metal oxides; Metastable phases; Morphology; multidisciplinary; Nanoribbons; Oxygen; Oxygen evolution reactions; Scanning electron microscopy; Science; Science (multidisciplinary); Solid phases; Spectrum analysis; Transmission electron microscopy
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-36833-1

Metastable metal oxides with ribbon morphologies have promising applications for energy conversion catalysis, however they are largely restricted by their limited synthesis methods. In this study, a monoclinic phase iridium oxide nanoribbon with a space group of C2/m is successfully obtained, which is distinct from rutile iridium oxide with a stable tetragonal phase (P42/mnm). A molten-alkali mechanochemical method provides a unique strategy for achieving this layered nanoribbon structure via a conversion from a monoclinic phase K 0.25 IrO 2 (I2/m (12)) precursor. The formation mechanism of IrO 2 nanoribbon is clearly revealed, with its further conversion to IrO 2 nanosheet with a trigonal phase. When applied as an electrocatalyst for the oxygen evolution reaction in acidic condition, the intrinsic catalytic activity of IrO 2 nanoribbon is higher than that of tetragonal phase IrO 2 due to the low d band centre of Ir in this special monoclinic phase structure, as confirmed by density functional theory calculations. Well-defined metastable phase nanostructures are a core issue for catalyst design. Here, the authors report metastable monoclinic phase IrO2 nanoribbons obtained via a molten-alkali mechanochemical method, which exhibit intrinsic high performance towards the acidic oxygen evolution reaction.