Premium
Manganese Oxide as an Inorganic Catalyst for the Oxygen Evolution Reaction Studied by X‐Ray Photoelectron and Operando Raman Spectroscopy
Author(s) -
Radinger Hannes,
Connor Paula,
Stark Robert,
Jaegermann Wolfram,
Kaiser Bernhard
Publication year - 2021
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.202001756
Subject(s) - x ray photoelectron spectroscopy , raman spectroscopy , birnessite , catalysis , oxide , oxygen evolution , valence (chemistry) , manganese , water splitting , amorphous solid , chemistry , inorganic chemistry , materials science , electrochemistry , chemical engineering , manganese oxide , electrode , crystallography , photocatalysis , biochemistry , physics , optics , organic chemistry , engineering
Manganese oxide (MnO x ) is considered a promising material for the oxygen evolution reaction (OER) to replace noble metal catalysts in water splitting. The improvement of MnO x requires mechanistic and kinetic knowledge of the four‐electron transfer steps of the OER. X‐ray photoelectron spectroscopy, a widely used tool to characterize the electronic structure of thin films, is used in combination with surface‐enhanced Raman spectroscopy to gain a deeper knowledge of the different mixed MnO x types and their respective change in chemical composition. Using Raman spectroscopy during electrochemical measurements, all samples were found to reveal Birnessite‐type MnO 2 motifs in alkaline media at an applied potential. Their activity correlates with two shifting Raman active modes, one of them being assigned to the formation of Mn III species, and one to the expansion of layers of MnO 6 octahedra. A special activation treatment leads independent of the starting material to a highly amorphous mixed‐valence oxide, which shows the highest OER activity.