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 2024-01-19T12:32:49Z 2024-01-19T12:32:49Z 2022-01-25 2022-03 0926-3373 https://pubs.kist.re.kr/handle/201004/115604 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 similar to 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. English ELSEVIER Role of surface steps in activation of surface oxygen sites on Ir nanocrystals for oxygen evolution reaction in acidic media Article 10.1016/j.apcatb.2021.120834 1 APPLIED CATALYSIS B-ENVIRONMENTAL, v.302 APPLIED CATALYSIS B-ENVIRONMENTAL 302 N scie scopus 000712024700001 2-s2.0-85117781612 Chemistry, Physical Engineering, Environmental Engineering, Chemical Chemistry Engineering Article INITIO MOLECULAR-DYNAMICS TOTAL-ENERGY CALCULATIONS DURABILITY OXIDATION ELECTROCATALYSIS DISSOLUTION CATALYSTS INSIGHTS METALS PH Electrocatalysts Oxygen evolution reaction Operando X-ray absorption spectroscopy Density functional theory Ir nanocrystals