Atomic Layer Deposition of Mixed-Layered Aurivillius Phase on TiO₂ Nanotubes: Synthesis, Characterization and Photoelectrocatalytic Properties

For the first time, one-dimensional phase-modulated structures consisting of two different layered Aurivillius phases with alternating five and six perovskite-like layers were obtained by atomic layer deposition (ALD) on the surface of TiO₂ nanotubes (Nt). It was shown that the use of vertically oriented TiO₂ Nt as the substrate and the ALD technology of a two-layer Bi₂O₃-FeO_x sandwich-structure make it possible to obtain a layered structure due to self-organization during annealing. A detailed study by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the coating is conformal. Raman spectroscopic analysis indicated the structure of the layered Aurivillius phases. Transient photocurrent responses under Ultraviolet-Visible (UV-Vis) light irradiation show that the ALD coating benefits the efficiency of photon excitation of electrons. The results of the photoelectrocatalytic experiments (PEC) with methyl orange degradation as a model demonstrate the significant potential of the synthesized structure as a photocatalyst. Photoluminescent measurement showed a decrease in the probability of recombination of photogenerated electron-hole pairs for ALD-coated TiO₂ Nt, which demonstrates the high potential of these structures for use in photocatalytic and photoelectrochemical applications.