Electron Correlations Engineer Catalytic Activity of Pyrochlore Iridates for Acidic Water Oxidation. Issue 6 (14th December 2018)

• Record Type: Journal Article
• Authors: Shang, Chunyan; Cao, Cong; Yu, Dayou; Yan, Yu; Lin, Yitao; Li, Hongliang; Zheng, Tingting; Yan, Xupeng; Yu, Wenchao; Zhou, Shiming; Zeng, Jie
• Is Part Of: Advanced materials. Volume 31:Issue 6(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-12-14
• Subjects: catalytic activity -- electron correlations -- iridate oxides -- oxygen evolution reaction; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201805104
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: 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 R2 Ir2 O7 (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. Abstract : 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.