Porous vs. Nanotubular Anodic TiO2: Does the Morphology Really Matters for the Photodegradation of Caffeine?

Abstract

Herein, the preparation of nanotubular and porous TiO2 structures (TNS) is presented for photocatalytic applications. Different TNS were prepared in three different types of glycerol- and ethylene glycol-based electrolytes on a large area (approx. 20 cm2) via anodization using different conditions (applied potential, fluoride concentration). Morphology, structure, and optical properties of TNS were characterized by Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD), and Diffuse Reflectance Spectroscopy (DRS), respectively. All TNS possess optical band-gap energy (EBG) in the range from 3.1 eV to 3.2 eV. Photocatalytic degradation of caffeine was conducted to evaluate the efficiency of TNS. Overall, nanotubular TiO2 possessed enhanced degradation efficiencies (up to 50% degradation) compared to those of porous TiO2 (up to 30% degradation). This is due to the unique properties of nanotubular TiO2, e.g., improved incident light utilization. As the anodization of large areas is, nowadays, becoming a trend, we show that both nanotubular and porous TiO2 are promising for their use in photocatalysis and could be potentially applicable in photoreactors for wastewater treatment. We believe this present work can be the foundation for future development of efficient TiO2 nanostructures for industrial applications.

PbS and PbO Thin Films via E-Beam Evaporation: Morphology, Structure, and Electrical Properties

“…The band gap is observed to increase with increasing temperature. The band gap of bulk PbS is 0.4 eV [ 31 ]. However, the band gap in the current study is sufficiently larger (2.12 eV) than the bulk value.…”

Synergistic effects of β-NaFeO2 ferrite nanoparticles for photocatalytic degradation, antibacterial, and antioxidant applications

“…However, they endure several challenges, such as the requirement of specic environmental conditions, longer remediation times, and potential sludge generation. [2][3][4][5][6] Additionally, chemical methods, e.g., ozonation, chlorination, or simple application of chemicals to degrade pollutants are oen used. However, these lead to the production of harmful by-products and can be economically and operationally inefficient.…”

Modification of Anodic Titanium Oxide Bandgap Energy by Incorporation of Tungsten, Molybdenum, and Manganese In Situ during Anodization

“…Besides their chemical composition, the main differences between these two porous materials are their morphology and applications. While AAO typically consists of well-ordered and straight to the metal substrate nanocapillaries and is mainly used as a template for nanofabrication, ATO is composed of nanotubes and is used as a photocatalyst [ 1 , 2 , 3 , 4 , 5 ].…”

“…The best composition for these generations of electrolyte for titanium anodization is an NH 4 F concentration in the range of 0.1–1.0 wt%, addition of water at the level of 0.1–5 wt%, voltage in the range of 10–60 V, and room temperature [ 11 ]. Normally, the applied anodization conditions such as voltage, temperature, and time, as well as the experimental setup [ 12 , 13 , 14 ] and electrolyte age [ 15 , 16 ], affect the ATO morphology, structure, and properties [ 5 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. For example, the change of electrolyte type to an alkaline one or change of the main solvent in the electrolyte from glycol to ethanol or glycerol [ 7 , 23 ] leads to the formation of anodic oxide film morphology with different characteristics to what is most known nowadays.…”