Abstract
The novelty of this work was to prepare a series of defect-rich colored TiO2 nanostructures, using a peroxo solvothermal-assisted, high-pressure nitrogenation method. Among these solids, certain TiO2 materials possessed a trace quantity of anatase–rutile heterojunctions, which are beneficial in obtaining high reaction rates in photocatalytic reactions. In addition, high surface area (above 100 m2/g), even when utilizing a high calcination temperature (500 °C), and absorption of light at higher wavelengths, due to the grey color of the synthesized titania, were observed as an added advantage for photocatalytic hydroxyl radical formation. In this work, we adopted a photoluminescent probe method to monitor the temporal evolution of hydroxyl radicals. As a result, promising hydroxyl radical formations were observed for all the colored samples synthesized at 400 and 500 °C, irrespective of the duration of calcination.
Highlights
The uniqueness of TiO2 in light-induced reactions, especially in photocatalysis, is unequivocally accepted, and this material is considered the most efficient photocatalyst due to its copious availability, low cost, non-toxicity, and photostability [1]
To synthesize the defect-rich grey titania nanoparticles, a peroxo solvothermal-assisted high-pressure nitrogenation method was utilized in this study
Except for the pristine titania (PT), all other synthesized samples comprised of 0.7–3.2 wt.% of nitrogen (Figure S1)
Summary
The uniqueness of TiO2 in light-induced reactions, especially in photocatalysis, is unequivocally accepted, and this material is considered the most efficient photocatalyst due to its copious availability, low cost, non-toxicity, and photostability [1]. Among the various phases of TiO2 , anatase is considered the most efficient and active photocatalytic phase [2]. The wide bandgap of anatase (3.2 eV) can efficiently reduce the electron–hole recombination as compared with rutile with narrower bandgap energy (3.0 eV) [3,4]. Anatase usually displays higher activity than rutile in photodegradation of environmental pollutants [5,6], while rutile is illustrated to be more active for photocatalytic water oxidation and overall water splitting [7,8]. Researchers have adopted various strategies for the synthesis of mixed-phase TiO2 structures. It is necessary to manage the existence of the rutile phase in trace amounts.
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