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

Abstract

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.