Due to their high activity and stability, Ir-based materials are state-of-the-art electrocatalysts for oxygen evolution reaction (OER) under acidic conditions. However, many factors such as the influence of the activation/conditioning protocol and the resulting oxidation state or the effect of electrolyte adsorption on activity are still debated or overlooked. Herein, Raman spectroscopy was performed on commercial Ir black and IrO nanopowders to reveal differences in the samples after activation, as well as adsorption of perchlorates. Specifically, three different activation protocols were performed, 0.05 to 1.45 V (activated), 0.05 to 1.6 V (activated-long range (l.r.)), and 1.1 to 1.6 V (activated-short range (s.r.)), resulting in different OER activity as well as different Raman spectra. However, only Ir(IV) bands remain visible in the Raman experiments, which was not sufficient to reveal the hydrated phases in the iridium samples. Therefore, experiments were performed, which allowed the observation of the hydrated phase, particularly for Ir black, but also showed adsorption of perchlorate anions. In addition, the influence of solvation on Raman band shifts is revealed - along with DFT calculations. Overall, this work paves the way for our future Raman spectroscopy experiments with iridium-based electrocatalysts during activation and OER.

中文翻译：

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Ir 金属纳米颗粒和 IrO2 用于酸性析氧反应：拉曼光谱的见解


由于其高活性和稳定性，铱基材料是酸性条件下析氧反应（OER）最先进的电催化剂。然而，许多因素，例如活化/调节方案的影响以及由此产生的氧化态或电解质吸附对活性的影响仍然存在争议或被忽视。在此，对商业 Ir 黑和 IrO 纳米粉末进行拉曼光谱分析，以揭示活化后样品的差异以及高氯酸盐的吸附情况。具体来说，执行了三种不同的激活方案：0.05 至 1.45 V（激活）、0.05 至 1.6 V（激活长程 (lr)）和 1.1 至 1.6 V（激活短程 (sr)），从而产生不同的 OER活性以及不同的拉曼光谱。然而，在拉曼实验中，只有 Ir(IV) 谱带仍然可见，这不足以揭示铱样品中的水合相。因此，进行了实验，不仅可以观察水合相，特别是铱黑，而且还显示了高氯酸根阴离子的吸附。此外，还揭示了溶剂化对拉曼带位移的影响以及 DFT 计算。总的来说，这项工作为我们未来在活化和 OER 过程中使用铱基电催化剂进行拉曼光谱实验铺平了道路。