Yue Shengnan, Praveen C S, Klyushin Alexander, Fedorov Alexey, Hashimoto Masahiro, Li Qian, Jones Travis, Liu Panpan, Yu Wenqian, Willinger Marc-Georg, Huang Xing
College of Chemistry, Fuzhou University, Fuzhou, China.
Qingyuan Innovation Laboratory, Quanzhou, China.
Nat Commun. 2024 Jun 1;15(1):4678. doi: 10.1038/s41467-024-49134-y.
Catalysts based on palladium are among the most effective in the complete oxidation of methane. Despite extensive studies and notable advances, the nature of their catalytically active species and conceivable structural dynamics remains only partially understood. Here, we combine operando transmission electron microscopy (TEM) with near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and density functional theory (DFT) calculations to investigate the active state and catalytic function of Pd nanoparticles (NPs) under methane oxidation conditions. We show that the particle size, phase composition and dynamics respond appreciably to changes in the gas-phase chemical potential. In combination with mass spectrometry (MS) conducted simultaneously with in situ observations, we uncover that the catalytically active state exhibits phase coexistence and oscillatory phase transitions between Pd and PdO. Aided by DFT calculations, we provide a rationale for the observed redox dynamics and demonstrate that the emergence of catalytic activity is related to the dynamic interplay between coexisting phases, with the resulting strained PdO having more favorable energetics for methane oxidation.
基于钯的催化剂是甲烷完全氧化中最有效的催化剂之一。尽管进行了广泛的研究并取得了显著进展，但对其催化活性物种的性质和可能的结构动力学仍只有部分了解。在这里，我们将原位透射电子显微镜（TEM）与近常压X射线光电子能谱（NAP-XPS）以及密度泛函理论（DFT）计算相结合，以研究甲烷氧化条件下钯纳米颗粒（NPs）的活性状态和催化功能。我们表明，颗粒尺寸、相组成和动力学对气相化学势的变化有明显响应。结合与原位观察同时进行的质谱（MS），我们发现催化活性状态呈现出钯和氧化钯之间的相共存和振荡相变。在DFT计算的帮助下，我们为观察到的氧化还原动力学提供了一个基本原理，并证明催化活性的出现与共存相之间的动态相互作用有关，由此产生的应变氧化钯对甲烷氧化具有更有利的能量学。
