Multi-Core-shell TiO2NPs@ZIF-8 Composite for Enhanced Photocatalytic Degradation and Adsorption of Methylene Blue and Rhodamine-B

Multi-Core-shell TiO(2)NPs@ZIF-8 composites were synthesized by insitu encapsulation of different amounts of TiO(2)NPs (150, 300 and 500 L suspension of TiO(2)NPs in methanol) in ZIF-8 at room temperature. Encapsulation of TiO(2)NPs in ZIF-8 was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. ZIF-8 and its core-shell composites have similar crystal structure and morphology as confirmed by powder X-ray diffraction analysis and scanning electron microscopy. The detailed photocatalytic degradation and adsorption studies of methylene blue and rhodamine-B were investigated by considering various factors, viz. amount of loading of TiO(2)NPs in ZIF-8, amount of photocatalyst, pH and initial concentration of the dye. At higher pH (11.5-12.6), TiO(2)NPs@ZIF-8 composite exhibited higher (approximate to 8 times) photocatalytic activity as compared to TiO(2)NPs and the optimum amount of TiO(2)NPs@ZIF-8 composite was 10mg for the maximum photodegradation of 3.19 mg L-1 (93%) and 2.4 mg L-1 (57%) of methylene blue and rhodamine-B, respectively.