Ab Initio Thermodynamics Insight into the Structural Evolution of Working IrO2 Catalysts in Proton-Exchange Membrane Electrolyzers
Ab Initio Thermodynamics Insight into the Structural Evolution of Working IrO2 Catalysts in Proton-Exchange Membrane Electrolyzers
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DOI：
10.1021/acscatal.9b00796
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发表时间：
2019-04
期刊：
影响因子：
12.9
通讯作者：
Daniel Opalka;C. Scheurer;K. Reuter
中科院分区：
文献类型：
--
作者：
Daniel Opalka;C. Scheurer;K. Reuter
At the cell voltages required to reach technologically viable current densities in proton-exchange membrane (PEM) electrolyzers, IrO2 catalysts are suspected to undergo a transformation to an amorphous hydrous form. Here, we present a systematic ab initio thermodynamics study analyzing the shape and stability of IrO2 nanoparticles in this potential range. Our results confirm a thermodynamic instability of the rutile crystal structure induced by the stabilization of highly oxidized O species at the surface already at onset potentials for the oxygen evolution reaction (OER). Intriguingly, this is preceded by a transformation of the equilibrium shape at even lower potentials. Instead of the well-studied IrO2(110) facets, this shape is dominated by IrO2(111) facets that have hitherto barely received attention. Our findings highlight the need to extend detailed characterization studies to this high-potential range, not the least to establish more suitable active-site models for the OER that may then serve as t...
