Reducing the noble metal loading and increasing the specific activity of the oxygen evolution catalysts are omnipresent challenges in proton-exchange-membrane water electrolysis, which have recently been tackled by utilizing mixed oxides of noble and non-noble elements. However, proper verification of the stability of these materials is still pending. Here we introduce a metric to explore the dissolution processes of various iridium-based oxides, defined as the ratio between the amounts of evolved oxygen and dissolved iridium. The so-called stability number is independent of loading, surface area or involved active sites and provides a reasonable comparison of diverse materials with respect to stability. The case study on iridium-based perovskites shows that leaching of the non-noble elements in mixed oxides leads to the formation of highly active amorphous iridium oxide, the instability of which is explained by the generation of short-lived vacancies that favour dissolution. These insights are meant to guide further research, which should be devoted to increasing the utilization of highly durable pure crystalline iridium oxide and finding solutions to stabilize amorphous iridium oxides.

在质子交换膜水电解中，降低贵金属载量和提高析氧催化剂的比活是无所不在的挑战，最近已通过利用贵金属和非贵金属元素的混合氧化物解决了这一难题。但是，这些材料的稳定性的适当验证仍在进行中。在这里，我们引入一种度量标准来探索各种铱基氧化物的溶解过程，定义为放出的氧气量与溶解的铱之间的比率。所谓的稳定性数与载荷，表面积或所涉及的活性位点无关，并且就稳定性而言提供了各种材料的合理比较。对铱基钙钛矿的案例研究表明，混合氧化物中非贵金属元素的浸出导致形成高活性非晶态氧化铱，其不稳定性可以通过产生有利于溶解的短时空位来解释。这些见解旨在指导进一步的研究，应致力于提高高度耐用的纯结晶氧化铱的利用率，并找到稳定非晶氧化铱的解决方案。