Controlled Synthesis of Pd/Pt Core Shell Nanoparticles Using Area-selective Atomic Layer Deposition.

Kun Cao,Bin Shan,Qianqian Zhu,Rong Chen

doi:10.1038/srep08470

Kun Cao, Bin Shan + Show 2 more

Open Access

https://doi.org/10.1038/srep08470

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Abstract

We report an atomic scale controllable synthesis of Pd/Pt core shell nanoparticles (NPs) via area-selective atomic layer deposition (ALD) on a modified surface. The method involves utilizing octadecyltrichlorosilane (ODTS) self-assembled monolayers (SAMs) to modify the surface. Take the usage of pinholes on SAMs as active sites for the initial core nucleation, and subsequent selective deposition of the second metal as the shell layer. Since new nucleation sites can be effectively blocked by surface ODTS SAMs in the second deposition stage, we demonstrate the successful growth of Pd/Pt and Pt/Pd NPs with uniform core shell structures and narrow size distribution. The size, shell thickness and composition of the NPs can be controlled precisely by varying the ALD cycles. Such core shell structures can be realized by using regular ALD recipes without special adjustment. This SAMs assisted area-selective ALD method of core shell structure fabrication greatly expands the applicability of ALD in fabricating novel structures and can be readily applied to the growth of NPs with other compositions.

Highlights

We report an atomic scale controllable synthesis of Pd/Pt core shell nanoparticles (NPs) via area-selective atomic layer deposition (ALD) on a modified surface
Since new nucleation sites can be effectively blocked by surface ODTS self-assembled monolayers (SAMs) in the second deposition stage, we demonstrate the successful growth of Pd/Pt and Pt/Pd NPs with uniform core shell structures and narrow size distribution
We demonstrate the realization of area-selective ALD (AS-ALD) NP growth process by fabricating Pd/Pt and Pt/ Pd core shell structures, which can be readily extended to the growth of other core shell structures

Summary

Atomic Layer Deposition

We report an atomic scale controllable synthesis of Pd/Pt core shell nanoparticles (NPs) via area-selective atomic layer deposition (ALD) on a modified surface. The size, shell thickness and composition of the NPs can be controlled precisely by varying the ALD cycles Such core shell structures can be realized by using regular ALD recipes without special adjustment. In this study we utilize similar approach to form pinhole structures, and grow core shell NPs using regular ALD recipes without special adjustments This new AS-ALD synthesis strategy utilizes pinholes on the unsaturated ODTS SAMs layer as active sites for the initial ALD nucleation while the closely packed ODTS layer blocks the precursor deposition during the cores formation process. ODTS SAMs enables selective growth of the second metal onto the cores, forming uniformly distributed core shell NPs. The size, shell thickness and composition of the NPs can be controlled precisely by varying the ALD cycles and significantly expands the applicability of this method. We demonstrate the realization of AS-ALD NP growth process by fabricating Pd/Pt and Pt/ Pd core shell structures, which can be readily extended to the growth of other core shell structures

Results and Discussion

Methods

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