Role of Surface Steps in Activation of Surface Oxygen Sites on Ir Nanocrystals for Oxygen Evolution Reaction in Acidic Media
- Authors
- Kim, Myeongjin; Park, Jinho; Wang, Maoyu; Wang, Qingxiao; Kim, Moon J.; Kim, Jin Young; Cho, Hyun-Seok; Kim, Chang-Hee; Feng, Zhenxing; Kim, Byung-Hyun; Lee, Seung Woo
- Issue Date
- Mar-2022
- Publisher
- Elsevier BV
- Keywords
- Density functional theory; Electrocatalysts; Ir nanocrystals; Operando X-ray absorption spectroscopy; Oxygen evolution reaction
- Citation
- Applied Catalysis B: Environmental, v.302, pp 1 - 10
- Pages
- 10
- Indexed
- SCIE
SCOPUS
- Journal Title
- Applied Catalysis B: Environmental
- Volume
- 302
- Start Page
- 1
- End Page
- 10
- URI
- https://scholarworks.bwise.kr/erica/handle/2021.sw.erica/115258
- DOI
- 10.1016/j.apcatb.2021.120834
- ISSN
- 0926-3373
1873-3883
- 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. © 2021 Elsevier B.V.
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