Operando Direct Observation of Stable Water-Oxidation Intermediates on Ca2-xIrO4 Nanocrystals for Efficient Acidic Oxygen Evolution.
Nano Lett
; 22(17): 6988-6996, 2022 Sep 14.
Article
em En
| MEDLINE
| ID: mdl-36005477
ABSTRACT
We report Ca2-xIrO4 nanocrystals exhibit record stability of 300 h continuous operation and high iridium mass activity (248 A gIr-1 at 1.5 VRHE) that is about 62 times that of benchmark IrO2. Lattice-resolution images and surface-sensitive spectroscopies demonstrate the Ir-rich surface layer (evolved from one-dimensional connected edge-sharing [IrO6] octahedrons) with high relative content of Ir5+ sites, which is responsible for the high activity and long-term stability. Combining operando infrared spectroscopy with X-ray absorption spectroscopy, we report the first direct observation of key intermediates absorbing at 946 cm-1 (Ir6+âO site) and absorbing at 870 cm-1 (Ir6+OO- site) on iridium-based oxides electrocatalysts, and further discover the Ir6+âO and Ir6+OO- intermediates are stable even just from 1.3 VRHE. Density functional theory calculations indicate the catalytic activity of Ca2IrO4 is enhanced remarkably after surface Ca leaching, and suggest IrOO- and IrâO intermediates can be stabilized on positive charged active sites of Ir-rich surface layer.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Nano Lett
Ano de publicação:
2022
Tipo de documento:
Article