Palladium hydrides (PdH_x) are pivotal in both fundamental research and practical applications across a wide spectrum. PdH_x nanocrystals, synthesized by heating in dimethylformamide (DMF), exhibit remarkable stability, granting them widespread applications in the field of electrocatalysis. However, this stability appears inconsistent with their metastable nature. The substantial challenges in characterizing nanoscale structures contribute to the limited understanding of this anomalous phenomenon. Here, through a series of well-conceived experimental designs and advanced characterization techniques, including aberration-corrected scanning transmission electron microscopy (AC-STEM), in situ X-ray diffraction (XRD), and time-of-flight secondary ion mass spectrometry (TOF-SIMS), we have uncovered evidence that indicates the presence of C and N within the lattice of Pd (PdC_xN_y), rather than H (PdH_x). By combining theoretical calculations, we have thoroughly studied the potential configurations and thermodynamic stability of PdC_xN_y, demonstrating a 2.5:1 ratio of C to N infiltration into the Pd lattice. Furthermore, we successfully modulated the electronic structure of Pd nanocrystals through C and N doping, enhancing their catalytic activity in methanol oxidation reactions. This breakthrough provides a new perspective on the structure and composition of Pd-based nanocrystals infused with light elements, paving the way for the development of advanced catalytic materials in the future.

中文翻译：

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在二甲基甲酰胺中加热时，哪些元素真正嵌入 Pd 晶格中？

氢化钯 (PdH _x ) 在基础研究和广泛的实际应用中都至关重要。在二甲基甲酰胺（DMF）中加热合成的PdH _x纳米晶体具有显着的稳定性，使其在电催化领域具有广泛的应用。然而，这种稳定性似乎与其亚稳态性质不一致。表征纳米级结构的巨大挑战导致对这种异常现象的理解有限。在这里，通过一系列精心设计的实验设计和先进的表征技术，包括像差校正扫描透射电子显微镜（AC-STEM）、原位X射线衍射（XRD）和飞行时间二次离子质谱法(TOF-SIMS)，我们发现了证据表明 Pd (PdC _x N _y )晶格内存在 C 和 N ，而不是 H (PdH _x )。通过结合理论计算，我们深入研究了PdC _x N _y的潜在构型和热力学稳定性，证明了C与N以2.5:1的比例渗透到Pd晶格中。此外，我们通过C和N掺杂成功地调节了Pd纳米晶的电子结构，增强了其在甲醇氧化反应中的催化活性。这一突破为注入轻元素的钯基纳米晶体的结构和组成提供了新的视角，为未来先进催化材料的发展铺平了道路。