InSitu Observation of Hydrogen-Induced Surface Faceting for Palladium-Copper Nanocrystals at Atmospheric Pressure

• Published in: Angewandte Chemie Vol. 128; no. 40; pp. 12615 - 12618
• Main Authors: Jiang, Ying, Li, Hengbo, Wu, Zhemin, Ye, Wenying, Zhang, Hui, Wang, Yong, Sun, Chenghua, Zhang, Ze
• Format: Journal Article
• Language: English; German
• Published: Weinheim Wiley Subscription Services, Inc 26-09-2016
• Subjects: Atmospheric pressure; Barometric pressure; Catalysis; Chemical synthesis; Chemistry; Computing time; Construction; Copper; Crystals; Cubes; Electron microscopy; Evolution; Gas pressure; Gases; Hydrogen; Mathematical analysis; Morphology; Nanocrystals; Nanostructure; Palladium; Particulates; Surface energy; Transmission electron microscopy
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201605956

Nanocrystal (NC) morphology, which decides the number of active sites and catalytic efficiency, is strongly determined by the gases involved in synthesis, treatment, and reaction. Myriad investigations have been performed to understand the morphological response to the involved gases. However, most prior work is limited to low pressures, which is far beyond realistic conditions. A dynamic morphological evolution of palladium-copper (PdCu) NC within a nanoreactor is reported, with atmospheric pressure hydrogen at the atomic scale. Insitu transmission electron microscopy (TEM) videos reveal that spherical PdCu particles transform into truncated cubes at high hydrogen pressure. First principles calculations demonstrate that the surface energies decline with hydrogen pressure, with a new order of [gamma]H-001<[gamma]H-110<[gamma]H-111 at 1bar. A comprehensive Wulff construction based on the corrected surface energies is perfectly consistent with the experiments. The work provides a microscopic insight into NC behaviors at realistic gas pressure and is promising for the shaping of nanocatalysts by gas-assisted treatments.