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Capturing Manganese Oxide Intermediates in Electrochemical Water Oxidation at Neutral pH by In Situ Raman Spectroscopy
Author(s) -
Cho Kang Hee,
Park Sunghak,
Seo Hongmin,
Choi Seungwoo,
Lee Moo Young,
Ko Changwan,
Nam Ki Tae
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202014551
Subject(s) - catalysis , manganese , raman spectroscopy , chemistry , oxygen evolution , electrochemistry , in situ , oxide , inorganic chemistry , manganese oxide , photochemistry , isotopic labeling , water splitting , redox , oxygen , reaction intermediate , electrode , photocatalysis , organic chemistry , physics , optics
Abstract Electrochemical water splitting is a promising means to produce eco‐friendly hydrogen fuels. Inspired by the Mn 4 CaO 5 cluster in nature, substantial works have been performed to develop efficient manganese (Mn)‐based heterogeneous catalysts. Despite improvements in catalytic activity, the underlying mechanism of the oxygen evolution reaction (OER) is not completely elucidated owing to the lack of direct spectroscopic evidence for the active Mn‐oxo moieties. We identify water oxidation intermediates on the surface of Mn 3 O 4 nanoparticles (NPs) in the OER at neutral pH by in situ Raman spectroscopy. A potential‐dependent Raman peak was detected at 760 cm −1 and assigned to the active Mn IV =O species generated during water oxidation. Isotope‐labeling experiments combined with scavenger experiments confirmed the generation of surface terminal Mn IV =O intermediates in the Mn‐oxide NPs. This study provides an insight into the design of systems for the observation of reaction intermediates.