Pd takes various chemical forms according to the types of catalysts and even its pristine chemical state is often subject to change in operation. To understand the mechanism how Pd-based catalysts activate reactions, it is important to have a capability to identify the surface chemical state of Pd-based catalysts in contact with reactants. In this study, we conducted in situ near ambient pressure-x-ray photoelectron spectroscopy (NAP-XPS) in gas conditions with water and oxygen for hydrous Pd oxide, which is also known as palladium hydroxide (Pd(OH)₂) and it is the key component of the Pearlman’s catalyst widely used for organic reactions. We found that hydrous Pd oxide showed different spectral features to that of anhydrous Pd oxide under gaseous water environments. We believe that this NAP-XPS study provides new information for a better identification of hydrous Pd oxide under reaction conditions, which is not available from conventional XPS in ultrahigh vacuum.

钯根据催化剂的类型采取各种化学形式，甚至其原始化学状态在操作中也经常发生变化。要了解 Pd 基催化剂如何激活反应的机制，重要的是有能力识别与反应物接触的 Pd 基催化剂的表面化学状态。在这项研究中，我们在水和氧气的气体条件下进行了原位接近环境压力 X 射线光电子能谱 (NAP-XPS) 水合氧化钯，也称为氢氧化钯 (Pd(OH) ₂)，它是广泛用于有机反应的珀尔曼催化剂的关键组分。我们发现水合氧化钯在气态水环境下表现出与无水氧化钯不同的光谱特征。我们相信，这项 NAP-XPS 研究为在反应条件下更好地识别水合 Pd 氧化物提供了新信息，这是超高真空中常规 XPS 无法获得的。