The fabrication and characterization of TiO2 nanospheres with high visible light photocatalytic activity by direct carbonization of block copolymer templates

Abstract

Titanium dioxide nanospheres with visible light photocatalytic activity were synthesized via a sol–gel approach using an amphiphilic diblock copolymer, polystyrene-block-polyacrylic acid (PS-b-PAA), as template at room temperature in toluene. The morphology and crystal structure of synthesized TiO₂ nanospheres were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The XRD pattern of TiO₂ nanospheres revealed the crystal transformation, resulting in the change of photocatalytic activity. The XPS pattern revealed the formation of Ti–O–C bonds upon carbonization, as a result of visible light absorption. The TiO₂ nanospheres had diameters ranging from 200 to 500 nm. The photodegradation experiments showed that such TiO₂ nanospheres had pronounced visible-light photocatalytic activity.