Role of Surface Steps in Activation of Surface Oxygen Sites on Ir Nanocrystals for Oxygen Evolution Reaction in Acidic Media
- Title
- Role of Surface Steps in Activation of Surface Oxygen Sites on Ir Nanocrystals for Oxygen Evolution Reaction in Acidic Media
- Author
- 김병현
- Keywords
- Electrocatalysts; Oxygen evolution reaction; Operando X-ray absorption spectroscopy; Density functional theory; Ir nanocrystals
- Issue Date
- 2022-03
- Publisher
- ELSEVIER
- Citation
- APPLIED CATALYSIS B-ENVIRONMENTAL, v. 302, article no. 120834, page. 1-10
- Abstract
- Ir and its oxide are the only available oxygen evolution reaction (OER) electrocatalysts with reasonably high activity and stability for commercial proton-exchange membrane electrolyzers. However, the establishment of structure–performance relationships for the design of better Ir-based electrocatalysts is hindered by their uncontrolled surface reconstruction during OER in acidic media. Herein, we monitor the structural evolution of two model Ir nanocrystals (one with a flat surface enclosed by (100) facets and the other with a concave surface containing numerous high-index planes) under acidic OER conditions. Operando X-ray absorption spectroscopy measurements reveal that the promotion of surface IrOx formation during the OER by the concave Ir surface with high-index planes results in a gradual OER activity increase, while a decrease in activity and limited oxide formation are observed for the flat Ir surface. After the activation process, the Ir concave surface exhibits ~ 10 times higher activity than the flat surface. Density functional theory computations reveal that Ir high-index surfaces are thermodynamically preferred for the adsorption of oxygen atoms and the formation of surface oxides under OER conditions. Thus, our work establishes a structure–performance relationship for Ir nanocrystals under operating conditions, providing new principles for the design of nanoscale OER electrocatalysts.
- URI
- https://www.sciencedirect.com/science/article/pii/S0926337321009590https://repository.hanyang.ac.kr/handle/20.500.11754/192029
- ISSN
- 0926-3373
- DOI
- https://doi.org/10.1016/j.apcatb.2021.120834
- Appears in Collections:
- COLLEGE OF SCIENCE AND CONVERGENCE TECHNOLOGY[E](과학기술융합대학) > CHEMICAL AND MOLECULAR ENGINEERING(화학분자공학과) > Articles
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