The sluggish kinetics, poor stability, and high iridium loading in acidic oxygen evolution reaction (OER) present significant challenges for proton exchange membrane water electrolyzers (PEMWE). While supported catalysts can enhance the utilization and activity of Ir atoms, they often fail to mitigate the detrimental effects of over-oxidation and dissolution of Ir. Here, we leverage the redox properties of the Mn3+/Mn4+ couple as electronic modulators to develop a low-iridium, durable electrocatalyst for acidic OER. Specifically, IrO2 nanoparticles are anchored onto MnO2 nanowires (denoted as IrO2/MnO2), through a molten salt-assisted synthesis method. This optimized IrO2/MnO2 electrocatalyst features a substantially reduced iridium content and enhanced electronic structure due to strong metal-support interactions. Remarkably, the IrO2/MnO2 catalyst demonstrates 7-fold increase in intrinsic activity and superior durability compared to commercial IrO2. Both theoretical and experimental results indicate that dynamic electron transfer between Ir and Mn facilitates the rapid formation of highly oxidized iridium sites while simultaneously preventing excessive oxidation, thereby enhancing both the kinetics and stability for OER. A PEMWE utilizing IrO2/MnO2 as the anode catalyst achieves 2000 mA cm−2 @ 1.89 V without requiring supporting acidic electrolyte. Importantly, the PEMWE exhibits negligible degradation under harsh industrial operating conditions (1000 mA cm−2) with an Ir loading as low as 0.5 mg cm−2, while maintaining a low energy consumption of 45.58 kWh kg−1 H2, corresponding to the green hydrogen production cost of $0.9 kg−1 H2, significantly lower than the 2026 US-DOE target, underscoring its potential for practical application.

中文翻译：

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IrO2/MnO2 金属氧化物载体相互作用可实现强大的酸性水氧化


酸性析氧反应 （OER） 中动力学缓慢、稳定性差和高铱负载量给质子交换膜水电解槽 （PEMWE） 带来了重大挑战。虽然负载型催化剂可以提高 Ir 原子的利用率和活性，但它们通常无法减轻 Ir 过度氧化和溶解的不利影响。在这里，我们利用 Mn3+/Mn4+ 偶的氧化还原特性作为电子调制器，开发一种用于酸性 OER 的低铱、耐用的电催化剂。具体来说，IrO2 纳米颗粒通过熔盐辅助合成方法锚定在 MnO2 纳米线（表示为 IrO2/MnO2）上。这种优化的 IrO2/MnO2 电催化剂具有显著降低的铱含量，并且由于强大的金属-载体相互作用而增强了电子结构。值得注意的是，与商业 IrO2 相比，IrO2/MnO2 催化剂的内禀活性提高了 7 倍，并且具有出色的耐久性。理论和实验结果表明，Ir 和 Mn 之间的动态电子转移有助于快速形成高度氧化的铱位点，同时防止过度氧化，从而增强 OER 的动力学和稳定性。使用 IrO2/MnO2 作为阳极催化剂的 PEMWE 可实现 2000 mA cm-2 @ 1.89 V，而无需支撑酸性电解质。重要的是，PEMWE 在恶劣的工业操作条件 （1000 mA cm-2） 下表现出可忽略不计的退化，Ir 负载低至 0.5 mg cm-2，同时保持 45.58 kWh kg-1 H2 的低能耗，对应于 0.9 美元 kg-1 H2 的绿色氢气生产成本，明显低于 2026 年 US-DOE 目标，突显了其实际应用的潜力。