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Nano Res-The work by Xiang Li reported a smart approach for constructing alloy surfaces


2017-06-01

 

Synthesis of bimetallic-alloy nanocrystals with controllable compositions and facets have attracted increasing attention due to their intrinsic physical and chemical properties. Most of recent works mainly focused on the fabrication of solid bimetallic alloy nanocrystals, as well as their application in catalysis. In this work, we report a versatile approach for the construction of ultrathin Pd-M alloy surfaces on the preformed Pd nanocrystals. Based on this approach, the surface of Pd nanocrystals can be easily transformed into Pd-M (M = Ag, Cu, and Ni) alloy surfaces directly. Both the composition and the shell thickness of the alloy surfaces can be manipulated by simply tuning the reaction parameters. The success of this synthesis mainly relies on the combination of the slow reduction of “M” ions and the subsequent diffusion of M ad-atoms into the surface lattice of Pd seeds under a high reaction temperature. In addition, the surface structure of the Pd-M alloy surfaces can also be controlled by using Pd seeds with different shapes, since the shape of Pd seeds can be well maintained during our synthesis. Theoretically, the active sites of a catalyst mainly locate at its surface. The successful formation of Pd-M alloy surfaces can maximally enhance the catalytic property of the original seeds. When served as the catalysts for hydrogenation of chloronitrobenzene, all of these Pd-M alloy surfaces exhibit much better selectivity of chloroaniline than the original Pd seeds. More significantly, the Pd-Ni alloy surfaces can show a selectivity as high as >99%, indicating the significance of our proposed approach in the rational design and fabrication of efficient bimetallic or even multimetallic alloy nanocatalysts.

 



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