Abstract
Natural kaolinite clays with different dimensionalities (including kaolinite nanoflakes and nanorods) supported TiO2 nanoparticles were successfully prepared via a facile sol-gel method. Moreover, comparisons between FK/TiO2 and RK/TiO2 nanocomposites are conducted in terms of matrix morphology, surface property, energy band structure and interfacial interaction. The effects of kaolinite microstructure, morphology and dimensionality on the interfacial characteristics and photocatalytic properties of the nanocomposites were investigated in detail. The results showed that TiO2 nanoparticles are more easily attached on the kaolinite nanoflakes, and possess more uniform distribution and smaller particle size than that of kaolinite nanorods. In particular, the FK/TiO2 nanocatalysts exhibit higher photocatalytic activity for the degradation of tetracycline hydrochloride than that of RK/TiO2 and bare TiO2, which is attributed to the stronger surface adsorptivity, higher loading efficiency and smaller grain size. Additionally, FK/TiO2 composites show excellent stability, which is ascribed to the intimate interfacial contact between two-dimensional kaolinite nanoflakes and TiO2 nanoparticles. Overall, the enhanced catalytic performance for FK/TiO2 composites is the synergistic effect of two-dimensional morphology, better adsorption capability and more active photocatalysis TiO2 species.
Highlights
Heterogeneous nanocomposites has attracted increasing attention because of the synergetic properties and potential applications as green methods to solve the energy and environmental problems[1]
Kaolinite clays possess plentiful hydroxyl groups on the surface, which is beneficial to surface modification and make kaolinite become a suitable matrix for anchoring of TiO2 nanoparticles to enhance the photocatalytic activity
Typical SEM and TEM analysis indicates that kaolinite clays used in the experiments naturally possess different morphologies, and the kaolinite particles all possess smooth surface without contamination (Fig. 1a,b,e,f)
Summary
FK/TiO2 has relatively higher specific surface area and lower pore volume, compared with RK/TiO2, which might be because the smaller size and uniform distribution of TiO2 nanoparticles attached on kaolinite nanoflakes These results are further confirmed by the observation from their pore size distribution calculated by BJH method (Fig. 3b). These characteristics seem to be responsible for enhanced catalytic activity and stability on the clays/TiO2 in comparison with bare TiO2. Based on the natural different morphologies and unique layered structure, the efficient assembly and high-density dispersion of uniform TiO2 nanoparticles were successfully achieved on the surface of kaolinite clays. Our insight into the comparison of different dimensionality of kaolinite clays to photocatalytic performance could be a reference function to the similar investigation, and clays/TiO2 composites have great potential applications to eliminate effectively antibiotics
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