Metal Organic Frameworks as Versatile Hosts of Au Nanoparticles in Heterogeneous Catalysis

The present review describes the state of the art of the use of metal organic framework (MOF)-encapsulated Au nanoparticles (NPs) as heterogeneous catalysts. The purpose is to show that catalysts with very good performance, frequently among the most active Au catalysts reported so far, can be obtained by incorporation of Au NPs inside MOFs. The available data indicate that the high catalytic activity of MOF-encapsulated Au NPs derives from (i) small particle size, (ii) high dispersion and homogeneous distribution inside MOFs crystals, (iii) stabilization of particle size by confinement of Au NPs inside MOFs cages, and (iv) the synergy that can arise by the combination of the activity of Au NPs and MOFs. After some introductory sections presenting general issues commenting about the relevance of Au catalysis, how to determine the internal versus external location of Au NPs, and evidence in support for catalyst stability, this mini review covers reactions using Au@MOFs as catalysts for oxidations, reductions, tandem processes, and photocatalysis with the emphasis in providing a comparison with the performance of other alternative Au-containing catalysts. In the final section, we summarize in our view the current achievements and which are the next targets in this area.