Atomic insights into the competitive edge of nanosheets splitting water
Journal article, 2024
The oxygen evolution reaction (OER) provides the protons for many electrocatalytic power-to-X processes, such as the production of green hydrogen from water or methanol from CO2. Iridium oxo-hydroxides (IOHs) are outstanding catalysts for this reaction because they strike a unique balance between activity and stability in acidic electrolytes. Within IOHs, this balance varies with atomic structure. While amorphous IOHs perform best, they
are least stable. The opposite is true for their crystalline counterparts. These rules-of-thumb are used to reduce the loading of scarce IOH catalysts and retain performance. However, it is not fully understood how activity and stability are related on the atomic level, hampering rational design. Herein, we provide simple design-rules (Figure 12) derived from literature and various IOHs within this study. We chose crystalline IrOOH nanosheets as our lead
material because they provide excellent catalyst utilization and a predictable structure. We found that nanosheets combine the chemical stability of crystalline IOHs with the activity amorphous IOHs. Their dense bonding network of pyramidal trivalent oxygens (μ3∆–O) provides structural integrity, while allowing reversible reduction to an electronically gapped state that diminishes the destructive effect of reductive potentials. The reactivity originates
from coordinative unsaturated edge sites with radical character, i.e. μ1–O oxyls. By comparing to other IOHs and literature, we generalized our findings and synthesized a set of simple rules that allow prediction of stability and reactivity of IOHs from atomistic models. We hope that these rules will inspire atomic design strategies for future OER catalysts.
are least stable. The opposite is true for their crystalline counterparts. These rules-of-thumb are used to reduce the loading of scarce IOH catalysts and retain performance. However, it is not fully understood how activity and stability are related on the atomic level, hampering rational design. Herein, we provide simple design-rules (Figure 12) derived from literature and various IOHs within this study. We chose crystalline IrOOH nanosheets as our lead
material because they provide excellent catalyst utilization and a predictable structure. We found that nanosheets combine the chemical stability of crystalline IOHs with the activity amorphous IOHs. Their dense bonding network of pyramidal trivalent oxygens (μ3∆–O) provides structural integrity, while allowing reversible reduction to an electronically gapped state that diminishes the destructive effect of reductive potentials. The reactivity originates
from coordinative unsaturated edge sites with radical character, i.e. μ1–O oxyls. By comparing to other IOHs and literature, we generalized our findings and synthesized a set of simple rules that allow prediction of stability and reactivity of IOHs from atomistic models. We hope that these rules will inspire atomic design strategies for future OER catalysts.
XPS
nanosheets
polymer electrolyte membrane (PEM)
stability
oxygen evolution reaction (OER)
electrochemistry
electronic structure
in situ
Iridium oxide
operando
NEXAFS
design rules
Author
Lorenz J. Falling
Max Planck Society
School of Natural Sciences, Technical University Munich
Woosun Jang
Max Planck Society
Yonsei University
Sourav Laha
National Institute of Technology, Durgapur
Max Planck Society
Thomas Götsch
Max Planck Society
Maxwell Terban
Max Planck Society
Rik Mom
Leiden University
Max Planck Society
Juan-Jesús Velasco-Vélez
Max Planck Society
ALBA Synchrotron Light Facility
Frank Girgsdies
Max Planck Society
Detre Teschner
Max Planck Society
Andrey Tarasov
Max Planck Society
Cheng-Hao Chuang
Tamkang University
Thomas Lunkenbein
Max Planck Society
Axel Knop-Gericke
Max Planck Society
Daniel Weber
Chalmers, Chemistry and Chemical Engineering, Energy and Material
Max Planck Society
Robert Dinnebier
Max Planck Society
Bettina V. Lotsch
Max Planck Society
Robert Schlögl
Max Planck Society
Travis E. Jones
Max Planck Society
Los Alamos National Laboratory
Journal of the American Chemical Society
0002-7863 (ISSN) 1520-5126 (eISSN)
Vol. 146 40 27886-27902Subject Categories (SSIF 2011)
Materials Chemistry
DOI
10.1021/jacs.4c10312
PubMed
39319770