Review of Graphene-Supported Metal Nanoparticles as New and Efficient Heterogeneous Catalysts

Graphene (Gr) is considered to be an ideal, two-dimensional catalytic support, due to its excellent electrical and thermal conductivity, mechanical strength and high surface area. In this paper we review recent progress in graphene applications as a catalyst support for graphene-supported metal nanoparticle heterogeneous catalysts, MeNP/Gr. For each catalyst the preparation method is described, and also the most significant properties that affect the catalytic behavior of the MeNP/Gr composite are discussed. The catalytic results, activity and selectivity are presented, emphasizing the role of the graphene support in the catalytic processes. Palladium was the most-used noble metal and a series of Pd/Gr, Pd/magnetite/Gr and Pd-Me/Gr composites were proposed for possible applications in different catalytic processes. Platinum- containing graphene composites were prepared and tested for hydrogenation and CO oxidation reactions. Among the applications, the most studied were processes involving hydrogen: hydrogenations, reductions and hydrogen generating reactions. Other reactions that are discussed are C-C cross coupling and CO oxidation. The role of graphene in the catalytic reactions is ascribed to its very good properties for dispersing and stabilizing the MeNPs, to the more favorable accessibility of reagent molecules to active centers due to the 2D configuration of the support, and to the intimate interaction between the MeNPs and graphene, which leads to efficient electron transfer and/or mass transport between the support and the metal.