A comparative study of TiO2 nanostructures prepared by one-step and two-step hydrothermal method: Physical and photoelectrochemical properties

Anatase TiO 2 films grown on Ti foils presenting nanosheet or nanowire morphologies were fabricated by one-step and two-step hydrothermal methods with different durations. Herein, the periodic patterns on the surface of Ti foils caused by the TiO 2 films peeling off promoted the growth of the two-step samples. Besides, the bandgaps of two-step samples were lower than those of one-step samples and the lowest bangap of 3.0 eV was obtained from the two-step sample with 4 h treatment. Meanwhile, this 4 h sample with the longest lifetime (79.5 ms) showing the optimized photocurrent density of 352.8 μA/cm 2 in the two-step samples was superior to the optimum one (4 h) in one-step samples with the density of 268.3 μA/cm 2 . Thus, relatively short hydrothermal treatment is benefit to the photoelectrochemical performance whether for one-step or two-step samples. Besides, the periodic patterns increased the density of second-step TiO 2 resulting in the narrowed bandgap and superior photocurrent density of two-step samples.