The Role of Lattice Defects on the Optical Properties of TiO₂ Nanotube Arrays for Synergistic Water Splitting.

ABSTRACT: In this study, we report a facile one-step chemical method to synthesize reduced titanium dioxide (TiO₂) nanotube arrays (NTAs) with point defects. Treatment with NaBH₄ introduces oxygen vacancies (OVs) in the TiO₂ lattice. Chemical analysis and optical studies indicate that the OV density can be significantly increased by changing reduction time treatment, leading to higher optical transmission of the TiO₂ NTAs and retarded carrier recombination in the photoelectrochemical process. A cathodoluminescence (CL) study of reduced TiO₂ (TiO_2-x) NTAs revealed that OVs contribute significantly to the emission bands in the visible range. It was found that the TiO₂ NTAs reduced for a longer duration exhibited a higher concentration of OVs. A typical CL spectrum of TiO₂ was deconvoluted to four Gaussian components, assigned to F, F⁺, and Ti³⁺ centers. X-ray photoelectron spectroscopy measurements were used to support the change in the surface chemical bonding and electronic valence band position in TiO₂. Electron paramagnetic resonance spectra confirmed the presence of OVs in the TiO_2-x sample. The prepared TiO_2-x NTAs show an enhanced photocurrent for water splitting due to pronounced light absorption in the visible region, enhanced electrical conductivity, and improved charge transportation.

SUBMITTER: Machreki M 

PROVIDER: S-EPMC10515401 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature