Inflating hollow nanocrystals through a repeated Kirkendall cavitation process

• Published in: Nature communications Vol. 8; no. 1; pp. 1261 - 9
• Main Authors: Tianou, He, Wang, Weicong, Yang, Xiaolong, Cao, Zhenming, Kuang, Qin, Wang, Zhao, Shan, Zhiwei, Jin, Mingshang, Yin, Yadong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 02.11.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/299/1013; 639/301/357/354; 639/638/549/2263; 639/925/357/551; Catalysis; Catalytic activity; Cavitation; Cavitation number; Coalescence; Coalescing; Crystals; Diffusion; Diffusion rate; Durability; Formic acid; Humanities and Social Sciences; Inflating; Kirkendall effect; Metals; multidisciplinary; Nanocrystals; Organic chemistry; Oxidation; Palladium; Phosphides; Phosphorus; Science; Science (multidisciplinary); Shells; Species diffusion; Thin walled shells
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-017-01258-0

The Kirkendall effect has been recently used to produce hollow nanostructures by taking advantage of the different diffusion rates of species involved in the chemical transformations of nanoscale objects. Here we demonstrate a nanoscale Kirkendall cavitation process that can transform solid palladium nanocrystals into hollow palladium nanocrystals through insertion and extraction of phosphorus. The key to success in producing monometallic hollow nanocrystals is the effective extraction of phosphorus through an oxidation reaction, which promotes the outward diffusion of phosphorus from the compound nanocrystals of palladium phosphide and consequently the inward diffusion of vacancies and their coalescence into larger voids. We further demonstrate that this Kirkendall cavitation process can be repeated a number of times to gradually inflate the hollow metal nanocrystals, producing nanoshells of increased diameters and decreased thicknesses. The resulting thin palladium nanoshells exhibit enhanced catalytic activity and high durability toward formic acid oxidation. Owing to their unique properties, hollow metal nanocrystals demonstrate greater catalytic promise than their solid counterparts. Here the authors produce hollow and inflated palladium nanocrystals with thin shells via a repeated Kirkendall cavitation process, and demonstrate their activity for formic acid oxidation.