Preparation and performance of graphene oxide /ZIF-7 composites

ZIF-7 crystals were in situ grown on graphene oxide (Go) by three synthetic routes, and the resulting graphene oxide/ZIF-7 composites (GZR-n) were characterized by PXRD, FT-IR, SEM, TEM, and N₂ isothermal adsorption-desorption. The effects of the synthetic routes on the growth, crystallinity, microscopic morphology and pore size of ZIF-7 crystals on graphene oxide were investigated. ZIF-7 crystals were grown on the surface and sheet of graphene oxide by three synthetic routes. The crystallinity of ZIF-7 crystals on GZR-n was significantly enhanced and some were wrapped by graphene oxide. The shape and size of ZIF-7 crystals growing on GZR-n were modulated by the synthesis routes. In particular, the ZIF-7 crystals were spherical particle with a dimeter of 50 nm in GZR-II. For GZR-I and GZR-III, the ZIF-7 crystals were regular polyhedron with a size of 200 nm. Additional, their dispersion properties in solvents, adsorption properties and kinetic simulations for organic dyes were explored. GZR-n showed good dispersion in methanol and chloroform. Compared with ZIF-7 crystals, the adsorption capacities of GZR-I, GZR-II and GZR-III for methylene blue were increased by 226%, 302% and 278%, respectively. The kinetic simulations indicated that the adsorption of GZR-II and GZR-III for methylene blue was chemisorption and that of GZR-I was physical adsorption.