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Polyhedral Palladium-Silver Alloy Nanocrystals as Highly Active and Stable Electrocatalysts for the Formic Acid Oxidation Reaction.

Fu GT, Liu C, Zhang Q, Chen Y, Tang YW - Sci Rep (2015)

Bottom Line: Polyhedral noble-metal nanocrystals have received much attention and wide applications as electrical and optical devices as well as catalysts.In this work, a straightforward and effective hydrothermal route for the controllable synthesis of the high-quality Pd-Ag alloy polyhedrons with uniform size is presented.As a preliminary electrochemical application, the Pd-Ag alloy polyhedrons are applied in the formic acid oxidation reaction, which shows higher electrocatalytic activity and stability than commercially available Pd black due to the "synergistic effects" between Pd and Ag atoms.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, P. R. China.

ABSTRACT
Polyhedral noble-metal nanocrystals have received much attention and wide applications as electrical and optical devices as well as catalysts. In this work, a straightforward and effective hydrothermal route for the controllable synthesis of the high-quality Pd-Ag alloy polyhedrons with uniform size is presented. The morphology, composition and structure of the Pd-Ag alloy polyhedrons are fully characterized by the various physical techniques, demonstrating the Pd-Ag alloy polyhedrons are highly alloying. The formation/growth mechanisms of the Pd-Ag alloy polyhedrons are explored and discussed based on the experimental observations and discussions. As a preliminary electrochemical application, the Pd-Ag alloy polyhedrons are applied in the formic acid oxidation reaction, which shows higher electrocatalytic activity and stability than commercially available Pd black due to the "synergistic effects" between Pd and Ag atoms.

No MeSH data available.


TEM images and XRD patterns of the intermediates collected at different growth stages: (A) 0 min, (B) 30 min, (C) 1 h and (D) 2 h.
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f4: TEM images and XRD patterns of the intermediates collected at different growth stages: (A) 0 min, (B) 30 min, (C) 1 h and (D) 2 h.

Mentions: To better understand the formation/growth process of the Pd–Ag alloy polyhedrons, the intermediate nanocrystals produced at different reaction stages were investigated by TEM and XRD. At the initial stage of the reaction (0 min), due to the presence of an excess amount of Cl–, white like-cube AgCl precipitate is generated instantaneously when AgNO3 is introduced in the reaction system (Fig. 4A-a), which is confirmed by XRD pattern of white precipitate (Fig. 4A-b). At 30 min, AgCl nanocubes evolve into the porous AgCl nanocrystals (Fig. 4B-a), because Ag+ ions gradually liberate from AgCl with the increase of reaction temperature33. Meanwhile, it is found that there are many tiny Pd–Ag alloy nanocrystals with different morphology (e.g., cubes, triangular plates and spheres) around the porous AgCl nanocubes, as indicated by the magnified TEM image and EDX line scanning profiles (Figure S4). Furthermore, XRD pattern of the intermediate nanocrystals at 30 min (Fig. 4B-b) also confirms that AgCl nanocrystals and the Pd–Ag alloy nanocrystals are coexistent in the reaction system. With an increase of reaction time to 1 h, the AgCl nanocrystals with lager size disappear, accompanying with the generation of the different-shaped Pd–Ag nanocrystals (Fig. 4C). As the reaction proceeded to 2 h, the complete Pd–Ag alloy polyhedrons generate (Fig. 4D). The shape evolution of the Pd–Ag alloy polyhedrons is also reflected in the color change of the reaction solution (Figure S5). The color of the solution changed from grey white to dark brown, and finally to black over the course of reaction, which corresponds to the sequential dissolution of AgCl precipitate and the formation of the Pd–Ag alloy polyhedrons.


Polyhedral Palladium-Silver Alloy Nanocrystals as Highly Active and Stable Electrocatalysts for the Formic Acid Oxidation Reaction.

Fu GT, Liu C, Zhang Q, Chen Y, Tang YW - Sci Rep (2015)

TEM images and XRD patterns of the intermediates collected at different growth stages: (A) 0 min, (B) 30 min, (C) 1 h and (D) 2 h.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556982&req=5

f4: TEM images and XRD patterns of the intermediates collected at different growth stages: (A) 0 min, (B) 30 min, (C) 1 h and (D) 2 h.
Mentions: To better understand the formation/growth process of the Pd–Ag alloy polyhedrons, the intermediate nanocrystals produced at different reaction stages were investigated by TEM and XRD. At the initial stage of the reaction (0 min), due to the presence of an excess amount of Cl–, white like-cube AgCl precipitate is generated instantaneously when AgNO3 is introduced in the reaction system (Fig. 4A-a), which is confirmed by XRD pattern of white precipitate (Fig. 4A-b). At 30 min, AgCl nanocubes evolve into the porous AgCl nanocrystals (Fig. 4B-a), because Ag+ ions gradually liberate from AgCl with the increase of reaction temperature33. Meanwhile, it is found that there are many tiny Pd–Ag alloy nanocrystals with different morphology (e.g., cubes, triangular plates and spheres) around the porous AgCl nanocubes, as indicated by the magnified TEM image and EDX line scanning profiles (Figure S4). Furthermore, XRD pattern of the intermediate nanocrystals at 30 min (Fig. 4B-b) also confirms that AgCl nanocrystals and the Pd–Ag alloy nanocrystals are coexistent in the reaction system. With an increase of reaction time to 1 h, the AgCl nanocrystals with lager size disappear, accompanying with the generation of the different-shaped Pd–Ag nanocrystals (Fig. 4C). As the reaction proceeded to 2 h, the complete Pd–Ag alloy polyhedrons generate (Fig. 4D). The shape evolution of the Pd–Ag alloy polyhedrons is also reflected in the color change of the reaction solution (Figure S5). The color of the solution changed from grey white to dark brown, and finally to black over the course of reaction, which corresponds to the sequential dissolution of AgCl precipitate and the formation of the Pd–Ag alloy polyhedrons.

Bottom Line: Polyhedral noble-metal nanocrystals have received much attention and wide applications as electrical and optical devices as well as catalysts.In this work, a straightforward and effective hydrothermal route for the controllable synthesis of the high-quality Pd-Ag alloy polyhedrons with uniform size is presented.As a preliminary electrochemical application, the Pd-Ag alloy polyhedrons are applied in the formic acid oxidation reaction, which shows higher electrocatalytic activity and stability than commercially available Pd black due to the "synergistic effects" between Pd and Ag atoms.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, P. R. China.

ABSTRACT
Polyhedral noble-metal nanocrystals have received much attention and wide applications as electrical and optical devices as well as catalysts. In this work, a straightforward and effective hydrothermal route for the controllable synthesis of the high-quality Pd-Ag alloy polyhedrons with uniform size is presented. The morphology, composition and structure of the Pd-Ag alloy polyhedrons are fully characterized by the various physical techniques, demonstrating the Pd-Ag alloy polyhedrons are highly alloying. The formation/growth mechanisms of the Pd-Ag alloy polyhedrons are explored and discussed based on the experimental observations and discussions. As a preliminary electrochemical application, the Pd-Ag alloy polyhedrons are applied in the formic acid oxidation reaction, which shows higher electrocatalytic activity and stability than commercially available Pd black due to the "synergistic effects" between Pd and Ag atoms.

No MeSH data available.