Akbari, Nader Shah, Jafar Hussain Hu, Cejun Nandy, Subhajit Aleshkevych, Pavlo Ge, Rile Farid, Sumbal Dong, Changchang Zhang, Liang Chae, Keun Hwa Xie, Wei Liu, Taifeng Wang, Junhu Najafpour, Mohammad Mahdi 2024-11-30T06:30:14Z 2024-11-30T06:30:14Z 2024-11-30 2025-02 1433-7851 https://pubs.kist.re.kr/handle/201004/151220 This study investigated the dynamic changes in NiFe (hydr)oxide and identified the role of high-valent Fe in the oxygen-evolution reaction (OER) within alkaline media via in situ techniques. Several high-valent Fe ions were found to remain considerably stable in the absence of potential in NiFe (hydr)oxide, even 96 hours after the OER. For Ni2+ hydroxide treated with 57Fe ions, where Fe sites are introduced onto the surface of Ni2+ hydroxide, no Fe4+ species were detected at the rate-determining step (RDS). The findings of this study suggested that the oxidation of bulk Fe ions, similar to Ni ions, to high valent forms, is charge accumulation without a direct role in OER; these results offered a novel perspective on manipulating Fe states to optimize OER efficacy. The prevailing hypothesis suggested that trace amounts of high-valent Fe ions, notably those on the surface, directly participate in OER. English John Wiley & Sons Ltd. A Hypothesis on the Function of High-Valent Fe in NiFe (Hydr)oxide in the Oxygen-Evolution Reaction Article 10.1002/anie.202418798 1 Angewandte Chemie International Edition, v.64, no.6 Angewandte Chemie International Edition 64 6 N scie scopus 001359658600001 2-s2.0-85209826736 Chemistry, Multidisciplinary Chemistry Article X-RAY-ABSORPTION WATER OXIDATION OXYHYDROXIDE ELECTROCATALYSTS ELECTRONIC-STRUCTURE NICKEL OXYHYDROXIDE IRON SITES IDENTIFICATION IMPURITIES CATALYSIS NiFe (hydr)oxide oxygen evolution reaction high-valent Fe4+ in situ techniques electrocatalysts alkaline conditions mechanism active sites