Tailored TiO₂−SrTiO₃ Heterostructure Nanotube Arrays for Improved Photoelectrochemical Performance

Abstract

TiO(2) nanotube arrays formed on Ti substrate by electrochemical anodization have been converted into TiO(2)-SrTiO(3) heterostructures by controlled substitution of Sr under hydrothermal conditions. The growth of SrTiO(3) crystallites on the nanotube array electrode was probed by electron microscopy and X-ray diffraction. As the degree of Sr substitution increases with the duration of hydrothermal treatment, an increase in the size of SrTiO(3) crystallites was observed. Consequently, with increasing SrTiO(3) fraction in the TiO(2)-SrTiO(3) nanotube arrays, we observed a shift in the flat band potential to more negative potentials, thus confirming the influence of SrTiO(3) in the modification of the photoelectrochemical properties. The TiO(2)-SrTiO(3) composite heterostructures obtained with 1 h or less hydrothermal treatment exhibit the best photoelectrochemical performance with nearly 100% increase in external quantum efficiency at 360 nm. The results presented here provide a convenient way to tailor the photoelectrochemical properties of TiO(2)-SrTiO(3) nanotube array electrodes and employ them for dye- or quantum-dot-sensitized solar cells and/or photocatalytic hydrogen production.

Hydrogenated TiO2/SrTiO3 porous microspheres with tunable band structure for solar-light photocatalytic H2 and O2 evolution

“…1. All the diffraction peaks are consistent with rutile TiO2 (JCPDS 75-6082) [6] and cubic perovskite SrTiO3 (JCPDS 35-0734) [10]. The typical diffraction peaks of rutile TiO2 and cubic perovskite SrTiO3 are observed in the XRD pattern of the TiO2/SrTiO3 sample.…”

“…The improved photocatalytic activity of these semiconductor composites originates from the rapid transfer of photogenerated electrons and holes from one component to the other. For TiO2/SrTiO3 composites, their significantly enhanced catalytic activities compared to those of TiO2 or SrTiO3 alone have also been reported in several studies [10][11][12][13][14]. However, TiO2/SrTiO3 composites do not absorb visible light because of their wide band gaps.…”

One-Dimensional Core/Shell Structured TiO2/ZnO Heterojunction for Improved Photoelectrochemical Performance

“…To date, a variety of inorganic heterojunction architectures have been developed to enhance the efficiency of photoelectrochemical water splitting cell. [22][23][24][25][26][27][28][29][30] In our study, we adapted this long-established strategy to enhance the photocatalytic activity of hydrothermally grown TiO 2 nanorod array. As a coupling material, we chose ZnO because its conduction band-edge is positioned at more negative potential in comparison with that of TiO 2 , thus being suitable for building the type-II band alignment (Scheme 1).…”

“…22 The negative shift in flat band potential is therefore indicative of the influence of ZnO on the Fermi level of TiO 2 . Coupling TiO 2 with ZnO aids in reducing charge recombination, which results in the accumulation of a larger number of electron in the TiO 2 /ZnO heterojunction.…”

Synthesis and photocatalytic activity of ZnxCd1-xS/TiO2 heterostructures nanofibre prepared by combining electrospinning and hydrothermal method

“…These well-separated photoelectrons and holes will further contribute to the degradation of the dye molecules. Meanwhile, the generated conduction band electrons (e -) of TiO 2 probably reacted with dissolved oxygen molecules to yield superoxide radical anions (O 2 -), with protonation which generated the hydroperoxy radicals (HO 2 -), producing the hydroxyl radical OH, which is known to be a strong oxidizing agent, 20 to decompose the organic dye. Therefore, the Zn x Cd 1-x S/TiO 2 heterostructures exhibits better photocatalytic properties than that of TiO 2 on the degradation of RhB under visible light irradiation.…”