Fabrication, characterization and photoelectrochemical property of TiO2 nano-pillar films conveniently grown on flexible stainless steel substrates

In this work, we reported a in situ synthesizing strategy for flexible TiO2 films by one-step hydrothermal treatment of Ti films deposited on the stainless steel (StS) substrate by direct current magnetron sputtering (DCMS) in tetramethylammonium hydroxide (TMAOH) solution. The structure and morphology of the films were characterized by field emission scanning electron microscopy (FESEM), X-Ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). Results show that the as-prepared TiO2 is anatase nano-pillar with tetrahedral and biconical-tip, and its elongated direction is [110] and the circumferential faces is {101} planes on tips. Higher substrate temperature is favorable to improve the density, adhesion and crystallinity of deposited Ti films. The microstructure of the deposited titanium films and the concentration of TMAOH solution can affect the morphologies of the TiO2 films, and then affect their photoelectrochemical properties. Photoelectrochemical analyses by transient photocurrent response and linear sweep voltammogram show that TiO2 film obtained in 1 M TMAOH solution from Ti film deposited at room temperature has the best photoelectrochemical property, followed by TiO2 film obtained in 1.5 M TMAOH solution from Ti film deposited at 600 °C, which is attributed to their larger surface area. This work provides further insights into conveniently in situ synthesize anatase nano-pillar film on non-Ti and acid nonresistant substrates.