Schweinar Kevin, Gault Baptiste, Mouton Isabelle, Kasian Olga
Max-Planck-Institut für Eisenforschung GmbH, Department of Microstructure Physics and Alloy Design, Max-Planck-Strasse 1, 40237 Düsseldorf, Germany.
Department of Materials, Imperial College London, Royal School of Mines, London SW7 2AZ, U.K.
J Phys Chem Lett. 2020 Jul 2;11(13):5008-5014. doi: 10.1021/acs.jpclett.0c01258. Epub 2020 Jun 12.
The development of efficient acidic water electrolyzers relies on understanding dynamic changes of the Ir-based catalytic surfaces during the oxygen evolution reaction (OER). Such changes include degradation, oxidation, and amorphization processes, each of which somehow affects the material's catalytic performance and durability. Some mechanisms involve the release of oxygen atoms from the oxide's lattice, the extent of which is determined by the structure of the catalyst. While the stability of hydrous Ir oxides suffers from the active participation of lattice oxygen atoms in the OER, rutile IrO is more stable and the lattice oxygen involvement is still under debate due to the insufficient sensitivity of commonly used online electrochemical mass spectrometry. Here, we revisit the case of rutile IrO at the atomic scale by a combination of isotope labeling and atom probe tomography and reveal the exchange of oxygen atoms between the oxide lattice and water. Our approach enables direct visualization of the electrochemically active volume of the catalysts and allows for the estimation of an oxygen exchange rate during the OER that is discussed in view of surface restructuring and subsequent degradation. Our work presents an unprecedented opportunity to quantitatively assess the exchange of surface species during an electrochemical reaction, relevant for the optimization of the long-term stability of catalytic systems.
高效酸性水电解槽的发展依赖于了解基于铱的催化表面在析氧反应（OER）过程中的动态变化。这些变化包括降解、氧化和非晶化过程，每一个过程都会以某种方式影响材料的催化性能和耐久性。一些机制涉及氧原子从氧化物晶格中的释放，其程度由催化剂的结构决定。虽然水合氧化铱的稳定性因晶格氧原子积极参与析氧反应而受到影响，但金红石型氧化铱更稳定，由于常用的在线电化学质谱灵敏度不足，晶格氧的参与情况仍存在争议。在此，我们通过同位素标记和原子探针断层扫描相结合的方法，在原子尺度上重新审视金红石型氧化铱的情况，并揭示氧化物晶格与水之间的氧原子交换。我们的方法能够直接可视化催化剂的电化学活性体积，并允许估计析氧反应过程中的氧交换速率，这将结合表面重构和随后的降解进行讨论。我们的工作为定量评估电化学反应过程中表面物种的交换提供了前所未有的机会，这对于优化催化系统的长期稳定性至关重要。
