Synthesis and improved photoelectrochemical performances of oxygen-deficient TiO₂/black-BaTiO₃/CdS multiple-heterojunction nanoarrays

TiO2-based photocatalysts have been extensively studied owing to their economic affordability, sensitive photo-responsivity, excellent chemical and thermal stability, abundance in nature, and other properties. However, insufficient visible-light absorption and photoelectrode efficiency greatly impede the practical application of TiO2-based photoelectrochemical (PEC) devices. Herein, a novel oxygen-deficient TiO2/black-BaTiO3(B-BTO)/CdS composite film was successfully fabricated by combining a hydrothermal method and Al-reduction and chemical bath deposition (CBD) techniques. A superior photocurrent density of 7.14 mA cm(-2) was achieved in the TiO2/B-BTO/CdS photoanode at 0 V vs. Ag/AgCl, which was approximately 35.7-fold and 2.2-fold higher than that of TiO2/BaTiO3 (TiO2/BTO) and CdS photoanodes, respectively. The improved PEC performance of the prepared nanocomposite can be attributed to the synergistic effect of the increased surface area of nanorod arrays, promoted light-harvesting capacity of oxygen-deficient B-BTO, spontaneous polarization of BTO, and TiO2/B-BTO/CdS multiple heterojunction structures. This work is expected to offer a new avenue for designing new oxygen-deficient TiO2-based nanocomposites with outstanding PEC activity.