Surface and bulk integrations of single-layered Au or Ag nanoparticles onto designated crystal planes {110} or {100} of ZIF-8

Abstract

Integration of other functional materials onto the surfaces or into the matrixes of metal-organic frameworks (MOFs) is a new strategy to acquire multifunctionality for MOFs. Herein, we report a novel means that can integrate ultrafine metal (Au or Ag) nanoparticles onto designated crystallographic planes of zeolitic imidazolate framework (i.e., ZIF-8). The key challenge herein is to determine appropriate surfactants that can help to generate the interaction between the incorporated metal nanoparticles and ZIF-8 phase. In our current work, single-layered metal nanoparticles have been added onto exterior surfaces and/or into interior bulk matrixes of ZIF-8 by forming coordination bonds. Such bonding is actually attained through the coordinative interaction between the surfactants of metal nanoparticles and partially coordinated Zn2+ions on the exterior surface of ZIF-8 crystals. Additional epitaxial growth of ZIF-8 can also be carried out, which turns the surface metal nanoparticles into ZIF-8 bulk phase. Adequate synthetic flexibility has been attained for complex architectures of metal-MOFs hybrid nanocomposites for the first time. Our Au-containing ZIF-8 also shows high catalytic activity for 4-nitrophenol reduction. © 2013 American Chemical Society.