Marín Enrique, Vendrell Xavier, Llorca Jordi
Institute of Energy Technologies, Department of Chemical Engineering and Center for Research in Multiscale Science and Engineering, Universitat Politècnica de Catalunya, EEBE, Eduard Maristany 10-14, 08019 Barcelona, Spain.
Department of Inorganic & Organic Chemistry and Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, 08028 Barcelona, Spain.
ACS Appl Nano Mater. 2025 Jun 4;8(23):12151-12163. doi: 10.1021/acsanm.5c01769. eCollection 2025 Jun 13.
Pd catalysts supported on CeO (1 wt % Pd) were synthesized using dry mechanochemical and incipient wetness impregnation methods. The mechanochemical synthesis was conducted in a planetary ball mill for 10 min with YSZ milling jar and balls at velocities ranging from 100 to 1000 rpm under various atmospheres (air, N, O, and 5% H/N). Catalysts were evaluated for their performance in the CO oxidation reaction and characterized at the nanoscale using Raman spectroscopy, XPS, XRD, H-TPR, XRF, nitrogen adsorption/desorption, and HAADF-STEM-EDX. Increased catalytic activity was observed in samples milled at lower velocities (100-250 rpm) in air, outperforming that of the conventional sample prepared by impregnation. This improvement appears to be attributed to changes in the surface nanostructure related to the metal-support interaction rather than the presence of oxygen vacancies. XPS revealed a higher concentration of PdO -Ce species in the most active milled sample, suggesting this as a reason for its superior catalytic performance. On the other hand, HAADF-STEM-EDX showed the presence of 2-3 nm Pd nanoparticles as well as Pd atoms/clusters anchored on crystalline ceria in the most active milled sample. Samples milled at high velocity (850-1000 rpm) showed a high degree of structural defects in the ceria crystallites and increased Ce species, but their catalytic performance was lower than the samples milled at low velocity. This study highlights the impact of milling conditions on the nanostructure and catalytic properties of Pd/CeO catalysts, with low-velocity milling emerging as a promising approach for enhancing catalytic activity.
采用干式机械化学法和初湿浸渍法合成了负载在CeO上的Pd催化剂（1 wt% Pd）。机械化学合成在行星式球磨机中进行10分钟，使用YSZ研磨罐和研磨球，在不同气氛（空气、N、O和5% H/N）下，转速范围为100至1000 rpm。对催化剂在CO氧化反应中的性能进行了评估，并使用拉曼光谱、X射线光电子能谱（XPS）、X射线衍射（XRD）、氢气程序升温还原（H-TPR）、X射线荧光光谱（XRF）、氮气吸附/脱附以及高角度环形暗场扫描透射电子显微镜-能谱分析（HAADF-STEM-EDX）在纳米尺度上进行了表征。在空气中以较低速度（100 - 250 rpm）研磨的样品中观察到催化活性增加，优于通过浸渍制备的传统样品。这种改善似乎归因于与金属 - 载体相互作用相关的表面纳米结构变化，而非氧空位的存在。XPS显示在活性最高的研磨样品中PdO - Ce物种的浓度较高，表明这是其优异催化性能的一个原因。另一方面，HAADF-STEM-EDX显示在活性最高的研磨样品中存在2 - 3 nm的Pd纳米颗粒以及锚定在结晶二氧化铈上的Pd原子/团簇。在高速（850 - 1000 rpm）下研磨的样品在二氧化铈微晶中显示出高度的结构缺陷且Ce物种增加，但其催化性能低于低速研磨的样品。本研究突出了研磨条件对Pd/CeO催化剂纳米结构和催化性能的影响，低速研磨成为增强催化活性的一种有前景的方法。
