Galyamin Dmitry, Tolosana-Moranchel Álvaro, Retuerto María, Rojas Sergio
Grupo de Energía y Química Sostenibles. Instituto de Catálisis y Petroleoquímica, CSIC, C/Marie Curie 2, 28049 Madrid, Spain.
JACS Au. 2023 Aug 23;3(9):2336-2355. doi: 10.1021/jacsau.3c00247. eCollection 2023 Sep 25.
Proton exchange membrane water electrolysis (PEMWE) is the technology of choice for the large-scale production of green hydrogen from renewable energy. Current PEMWEs utilize large amounts of critical raw materials such as iridium and platinum in the anode and cathode electrodes, respectively. In addition to its high cost, the use of Ir-based catalysts may represent a critical bottleneck for the large-scale production of PEM electrolyzers since iridium is a very expensive, scarce, and ill-distributed element. Replacing iridium from PEM anodes is a challenging matter since Ir-oxides are the only materials with sufficient stability under the highly oxidant environment of the anode reaction. One of the current strategies aiming to reduce Ir content is the design of advanced Ir-mixed oxides, in which the introduction of cations in different crystallographic sites can help to engineer the Ir active sites with certain characteristics, that is, environment, coordination, distances, oxidation state, etc. This strategy comes with its own problems, since most mixed oxides lack stability during the OER in acidic electrolyte, suffering severe structural reconstruction, which may lead to surfaces with catalytic activity and durability different from that of the original mixed oxide. Only after understanding such a reconstruction process would it be possible to design durable and stable Ir-based catalysts for the OER. In this Perspective, we highlight the most successful strategies to design Ir mixed oxides for the OER in acidic electrolyte and discuss the most promising lines of evolution in the field.
质子交换膜水电解（PEMWE）是利用可再生能源大规模生产绿色氢气的首选技术。目前的PEMWE分别在阳极和阴极电极中大量使用铱和铂等关键原材料。除了成本高昂外，使用基于铱的催化剂可能是PEM电解槽大规模生产的关键瓶颈，因为铱是一种非常昂贵、稀缺且分布不均的元素。从PEM阳极中替代铱是一项具有挑战性的任务，因为氧化铱是阳极反应的高氧化环境下唯一具有足够稳定性的材料。当前旨在降低铱含量的策略之一是设计先进的铱混合氧化物，其中在不同晶体学位置引入阳离子有助于设计具有特定特性（即环境、配位、距离、氧化态等）的铱活性位点。该策略也有其自身的问题，因为大多数混合氧化物在酸性电解质中的析氧反应（OER）过程中缺乏稳定性，会经历严重的结构重构，这可能导致表面的催化活性和耐久性与原始混合氧化物不同。只有在了解这种重构过程之后，才有可能设计出用于OER的耐用且稳定的基于铱的催化剂。在这篇展望文章中，我们重点介绍了在酸性电解质中设计用于OER的铱混合氧化物的最成功策略，并讨论了该领域最有前景的发展方向。
