Directed synthesis of hierarchical nanostructured TiO2 catalysts and their morphology-dependent photocatalysis for phenol degradation

Nanostructured TiO2 with different hierarchical morphologies were synthesized via a warmly hydrothermal route. The properties of the products were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N-2 adsorption, UV-vis spectroscopy, etc. Two of the products TiO2 1D nanorods (one-dimensional rutile TiO2 nanorods) and TiO2 3D(0D) microspheres (three-dimensional anatase TiO2 nanoparticle assemble:d microspheres) exhibited superior photocatalytic effects on phenol degradation under UV illumination, compared with TiO2 3D(1D) microspheres (three-dimensional rutile TiO2 nanorods-assembled microspheres). Moreover, TiO2 3D(0D) was superior to TiO2 1D, as indicated by a 30% higher mineralization of dissolved phenol. Dihydroxybenze, 4,4'-dihydroxybiphenyl, benzoquinone, maleic anhydride, etc. were identified as the degradation intermediates. The excellent catalytic effect was attributed to the structural features of TiO2 1D nanorods and TiO2 3D(0D) microspheres, that is, a larger amount of surface active sites and a higher band gap energy resulted in more efficient decomposition of organic contaminants.