Core@shell structured nanoparticles can unit different materials and provide possibilities to create new or synergistic functions, extend service life or reduce the cost.The selection of materials and the morphologies directly affect the synergistic properties.Metal organic frameworks (MOFs) offer exceptional functions for catalysis and gas separation due to their unique inorganic-organic framework structure, large surface area and high porosity.We introduce a facile synthesis route to form POP/ZIF-8 core@shell nanospheres at room temperature.Cyclomatrix poly(organophosphazenes) (POP) nanospheres were synthesised via a rapid one-step polycondensation reaction under untrasonication, zeolitic imidazolate framework-8 (ZIF-8) nanocrystals were synthesised in situ to form a shell layer onto the POP spheres at room temperature. The resultant POP/ZIF-8 core-shell particles were uniform and monodispersed, with a POP core of ~200 nm, and a ZIF-8 shell of tuneable thickness. By increasing the reaction time or composition ratio of ZIF-8/POP, the ZIF-8 shell thickness was increased from 50 nm to 100 nm. This is due to the synthetic versatilities of ZIF-8 and POPs. As shown by XRD, the characteristic peaks of the ZIF-8 crystals at planes (011), (002), (112), (022), (013), (222) were also observed in the POP/ZIF-8 core@shell structures, indicating the ZIF-8 remains highly crystalline diffraction patterns in the composite spheres.The Langmuire surface area of ZIF-8 was 1930 m2/g, the surface area of POP/ZIF-8 particles reached 1557 m2/g, which has significantly increased as compared to original POP spheres, 12 m2/g. This further demonstrates that the ZIF-8 layer are formed uniformly on the surface of the POPs and contribute to the surface area and porosity. After carbonisation at 600°C for 2h, the spherical morphology of POP/ZIF-8 particles were well preserved and showed a surface area of ~111 m2/g. This reduction is accounted for the low thermal stability of ZIF-8, which starts to degrade from 250○C, and lose crystal structure at ~400°C. Resultant porous carbon spheres contain 20 wt% carbon, 34% Zn, and 18% heteroatoms (N, P, S) in weight ratio, as characterised by EDS. Core-shell carbon nanostructures with highly doped heteroatoms and metal contents show promise to create pseudo/redox reactive sites for electrochemical energy storage applications.The facile ambient synthesis procedure is also advantageous over most reported methods in creating core-shell nanomaterials.

Characterization of core-shell structured polymer/ZIF-8 porous nanomaterials

256th National Meeting (2018)

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