Facile synthesis of micron‐sized hollow copper spheres with ZSM‐5 molecular sieve as a template

Abstract

AbstractA new, well‐designed type of micron‐sized hollow copper spheres was synthesized in this article. The process was performed using ZSM‐5 molecular sieve as a template. It has the prominent advantage in that the various stages of pretreatment for the core material can be omitted because of the inherent nature of the ZSM‐5 molecular sieve. The surface of the sieve consists entirely of negatively charged oxygen sites such that free Cu2+ ions can easily be adsorbed and reduced there, acting thereafter as a seed and self‐catalyst for electroless plating of copper so as to lead to the formation of interconnected Cu particles around the external surface of the ZSM‐5 molecular sieve. Moreover, there are many holes with a size of more than 5 × 5 Å2 on the surface of the ZSM‐5 molecular sieve, which can act as concavities that the reduced Cu can ‘rivet’ into, resulting in the link between the molecular sieve and the reduced Cu being stronger. In addition, the ZSM‐5 molecular sieve has the merits of ease of removal, low cost, and less aggregation owing to its micrometer size, and it avoids the use of nonvolatile surfactants, which may be adsorbed onto the reduced Cu and then interfere with the possible application of the hollow copper spheres in catalysis and in analytical devices based on surface‐enhanced Raman scattering (SERS) spectroscopy. The copper spheres obtained show enhanced Raman scattering in the presence of adsorbed 4‐mercaptobenzoic acid (4‐MBA) with excitation at 632.8 nm, and the enhancement factor reaches ∼7 × 103. The new micron‐sized hollow copper spheres are produced in a simple and cost‐effective method; so they are expected to play an important role in the fields of catalysts, fillers, and engineering, and in the development of SERS‐based analytical devices. The synthetic method may represent a novel route to prepare hollow metal spheres, which is a subject of intense interest. Copyright © 2009 John Wiley & Sons, Ltd.