Defective TiO₂ Nanotube Arrays for Efficient Photoelectrochemical Degradation of Organic Pollutants

Abstract

Oxygen vacancies (OVs) are one of the most critical factors that enhance the electrical and catalytic characteristics of metal oxide-based photoelectrodes. In this work, a simple procedure was applied to prepare reduced TiO2 nanotube arrays (NTAs) (TiO2–x ) via a one-step reduction method using NaBH4. A series of characterization techniques were used to study the structural, optical, and electronic properties of TiO2–x NTAs. X-ray photoelectron spectroscopy confirmed the presence of defects in TiO2–x NTAs. Photoacoustic measurements were used to estimate the electron-trap density in the NTAs. Photoelectrochemical studies show that the photocurrent density of TiO2–x NTAs was nearly 3 times higher than that of pristine TiO2. It was found that increasing OVs in TiO2 affects the surface recombination centers, enhances electrical conductivity, and improves charge transport. For the first time, a TiO2–x photoanode was used in the photoelectrochemical (PEC) degradation of a textile dye (basic blue 41, B41) and ibuprofen (IBF) pharmaceutical using in situ generated reactive chlorine species (RCS). Liquid chromatography coupled with mass spectrometry was used to study the mechanisms for the degradation of B41 and IBF. Phytotoxicity tests of B41 and IBF solutions were performed using Lepidium sativum L. to evaluate the potential acute toxicity before and after the PEC treatment. The present work provides efficient PEC degradation of the B41 dye and IBF in the presence of RCS without generating harmful products.

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

“…The smaller arcs, higher or lower frequencies, of the Nyquist plots decreased in the following order: 0 h > 2 h > 24 h > 16 h (Figure d). This result suggests that the electron transfer in the samples treated at 16 h is more efficient than that for the other samples. , …”

Synergy of Nd:YAG Picosecond Pulsed Laser Irradiation and Electrochemical Anodization in the Formation of TiO2 Nanostructures for the Photocatalytic Degradation of Pesticide Carbofuran

“…Different strategies, including hydrogenation, thermal reduction, electrochemical reduction, and liquid-phase reduction, have been developed to introduce V O in TiO 2 lattices. However, certain strategies may require high temperatures, harsh synthetic conditions, or toxic chemicals, which can be challenging [19,20].…”