Design and synthesis of porous C-ZnO/TiO2@ZIF-8 multi-component nano system via pyrolysis strategy with high adsorption capacity and visible light photocatalytic activity

With the regular structures composed of metal clusters and organic ligands, metal-organic frameworks (MOFs) are expected to be the competent stabilizing matrix for nanoparticles and the excellent precursor of metal oxide with carbon species by means of high temperature pyrolysis, resulting to porous architectures with unexpected adsorptive or catalytic properties. Herein, we design and propose a facile route for preparing porous Carbon doped ZnO/TiO2@ZIF-8 (C-ZnO/TiO2@ZIF-8) multi-component nano-platform using TiO2 coated ZIF-8 as precursor and template followed by thermal calcination. The resulted C-ZnO/TiO2@ZIF-8 nanocrystal simultaneously possesses original ZIF-8 morphology and porous structure with connected ZnO nanoparticles. As a result, C-ZnO/TiO2@ZIF-8 shows obviously better adsorption affinity towards methylene blue (MB). Moreover, benefit from the TiO2 coating outside ZIF-8 matrix, escape of carbon species which originate from pyrolysis of organic ligands is efficiently inhibited, with the resulted materials doped with abundant carbon. Therefore, charge transfer and isolation of the resulted catalyst are promoted accordingly, with catalytic activity of the prepared C-ZnO/TiO2@ZIF-8 multi-component photocatalyst significantly increased by 1.8-fold and 3.0-fold compared to ZnO@ZIF-8 photocatalyst under irradiation of UV and visible light, respectively.