Synthesis and characterization of ZrO2@SiO2 core-shell nanostructure as nanocatalyst: Application for environmental remediation of rhodamine B dye aqueous solution

ZrO2@SiO2 core-shell nanostructures were synthesized by a facile two-step hydrothermal plus Stober chemical route. The structure, morphology and properties of the nanoparticles were characterized using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, zeta-potential measurements, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). XRD confirmed the presence of tetragonal ZrO2 crystalline and amorphous SiO2 phases. FTIR analysis confirmed the existence of Zr-O-Si bonds at the surface of the core-shell nanostructures. According to the UV-Vis spectroscopy measurements, the energy band gap value of the uncoated ZrO2 nanoparticles was estimated to be 5.13 eV and the excitation energy (energy band discontinuity) of the ZrO2@SiO2 core-shell nanostructures was found to be 2.31 eV. Transmission electronic microscopy results showed 5-8 run ZrO2 nanoparticles highly crystalline and fully covered by amorphous and uniform SiO2 layer 10-15 nm wide, which is an evidence of the core-shell structure. Photocatalytic performance of ZrO2@SiO2 core-shell nanostructures was carried out using rhodamine B dye in aqueous solution at room temperature under UV light irradiation. ZrO2@SiO2 core-shell nanostructures showed better photocatalytic activities in comparison to the as prepared ZrO2 and SiO2 samples. The enhanced photocatalytic performance for ZrO2@SiO2 core-shell nanostructures may be the result of the Zr-O-Si interfacial layer narrowing the energy gap needed to electron-hole pairs creation, thus enhancing photoinduced charges generation and reducing charges recombination.