Electron Correlations Engineer Catalytic Activity of Pyrochlore Iridates for Acidic Water Oxidation

The development of highly efficient oxygen‐evolving catalysts compatible with powerful proton‐exchange‐membrane‐based electrolyzers in acid environments is of prime importance for sustainable hydrogen production. In this field, understanding the role of electronic structure of catalysts on catalytic...

Full description

Saved in:
Bibliographic Details
Published in:Advanced materials (Weinheim) 2019-02, Vol.31 (6), p.e1805104-n/a
Main Authors: Shang, Chunyan, Cao, Cong, Yu, Dayou, Yan, Yu, Lin, Yitao, Li, Hongliang, Zheng, Tingting, Yan, Xupeng, Yu, Wenchao, Zhou, Shiming, Zeng, Jie
Format: Article
Language:English
Subjects:
Acidic oxides
Acidic water
Catalysis
Catalysts
Catalytic activity
Chemical evolution
electron correlations
Electronic structure
Electrons
Hydrogen production
iridate oxides
Materials science
Metal ions
Oxidation
Oxygen
oxygen evolution reaction
Rare earth elements
Reaction kinetics
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The development of highly efficient oxygen‐evolving catalysts compatible with powerful proton‐exchange‐membrane‐based electrolyzers in acid environments is of prime importance for sustainable hydrogen production. In this field, understanding the role of electronic structure of catalysts on catalytic activity is essential but still lacking. Herein, a family of pyrochlore oxides R2Ir2O7 (R = rare earth ions) is reported as acidic oxygen‐evolving catalysts with superior‐specific activities. More importantly, it is found that the intrinsic activity of this material significantly increases with the R ionic radius. Electronic structure studies reveal that the increased R ionic radius weakens electron correlations in these iridate oxides. This weakening induces an insulator–metal transition and an enhancement of IrO bond covalency, both of which promote oxygen evolution kinetics. This work demonstrates the importance of engineering the electron correlations to rationalize the catalytic activity toward water oxidation in strongly correlated transition‐metal oxides. The increased R ionic radius of pyrochlore‐type iridate oxides weakens the electron correlations via broadening the Ir 5d bandwidths, which gives rise to an insulator–metal transition and a strengthened hybridization between Ir 5d and O 2p orbitals, affording a highly active electrocatalyst for the oxygen evolution reaction in acid media.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.201805104