3D TiO₂ nanobipyramids (TiO₂-NPs) and 1D TiO₂ nanobelts (TiO₂-NBs) were synthesized from potassium titanate K₂Ti₆O₁₃ and characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) patterns and fast Fourier transform (FFT). The as-synthesized 3D TiO₂ nanobipyramids and 1D TiO₂ nanobelts all show high {101} facet exposed percentages and were used to investigate the shape effect of TiO₂ with the same facet exposure. 3D TiO₂ nanobipyramids (101) showed higher photocatalytic activity than 1D TiO₂ nanobelts (101). The reasons were discussed using ROS (reactive oxygen species) production, time-resolved photoluminescence spectra, XPS (X-ray photoelectron spectroscopy) spectra and ATR-IR (attenuated total reflectance infrared spectroscopy) spectra. The postulated mechanism suggests that 3D TiO₂ nanobipyramids have more step edges which results in more –OH/H₂O molecule adsorption and longer life times of photoinduced carriers than 1D TiO₂ nanobelts.