Mof-graphene Composites: an Insight into the Texture and Adsorption Properties of New Materials

Introduction A new class of materials called metal-organic frameworks (MOFs) introduced by Yaghi and coworkers has drawn the attention of many scientists [1] owing to their high porosity and their “cumulative” features originating from combining both inorganic and organic solids via assembly of metallic ions and organic ligands [1]. Their applications include gas separation/purification/storage and catalysis [1]. Despite their interesting properties, MOFs suffer from some limitations. One is their instability towards the solvent removal step performed during their synthesis [1]. Other drawbacks include their inability to provide strong, nonspecific interactions to retain small molecules of gas and the collapse of some MOF networks in the presence of humidity [2]. To address these issues and to expand the field of applications of MOFs, the concept of MOF-based composites has been developed. Only a few composites have been reported so far such as: MOF/substrate (e.g. silica) to be used in membrane fabrication [3] and MOF/carbon nanotubes to increase hydrogen storage and water stability [4]. In this study, we propose to synthesize and test for ammonia adsorption MOF/graphite oxide (GO) composites. GO is obtained by oxidation of graphite which leads to the formation of various oxygen groups on the basal planes and the edges of the graphene layers [5]. The graphene layers from GO are expected to increase the dispersive forces in MOFs and thus to enhance the retention of small gas molecules.