Tuning of band gap in TiO₂and ZnO nanoparticles by selective doping for photocatalytic applications

Fly ash supported photocatalytic nanocomposite poly(3,4‐ethylenedioxythiophene)/TiO2 for azo dye removal under simulated solar irradiation

“…That results in reaction of electron in the conduction band with the oxygen to form O 2 · – superoxide radicals and holes in the valence band with the water to form OH · radicals responsible for the oxidation process of the pollutants. However, the photocatalytic process with TiO 2 and ZnO catalysts is effective only under UV‐A irradiation due to their high band gap of 3.2 and 3.4 eV, respectively . Since the UV‐A irradiation in the solar light occupies only a small fraction (3%–5%) and visible irradiation is insufficient to excite electrons for the generation of free radicals, the activation of catalyst is still an intriguing challenge.…”

Lattice distortion mechanism study of TiO2 nanoparticles during photocatalysis degradation and reactivation

“…Owing to the low intensity (<1%) of the longest lifetime component τ 3 , which could be inferred as the existence of ortho-positronium (o-Ps) formation, its effect was not discussed in this work. 11,21 For the samples determined over multiple measurements in the present work, the results were resolved into components by the PATFIT program with good reduced x 2 around unity, and the best-fitting parameter ranged from 0.95 to 1.1 after subtraction of the source contribution and a constant background. 12,21 Fig .…”

“…11,21 For the samples determined over multiple measurements in the present work, the results were resolved into components by the PATFIT program with good reduced x 2 around unity, and the best-fitting parameter ranged from 0.95 to 1.1 after subtraction of the source contribution and a constant background. 12,21 Fig . 1 illustrates the typical positron lifetime spectra from four samples.…”

“…12,23 For the shorter component τ 1 , it is usually denote to annihilation of positrons at the defect free sits, and positrons at the defects such as individual vacancies or small vacancy at grain boundaries. 11,19,21,24 In general, the thermalized positrons annihilate from the perfect lattice with electrons. The lifetime of the positrons in this state is known as bulk lifetime, which denotes as the τ b =139 for pristine TiO 2 , and the fast para-positronium annihilation (125 ps) has little effect owing to the low intensity of τ 3 (0∼0.2%).…”

“…11,19,20 Recently, PALS has been widely applied in the fields of solid materials, especially in condensed substances, materials physics, and also in physics, chemistry, materials science and biology, etc. 19,21,22 In this research, in addition to PALS and HRTEM, photoluminescence spectroscopy (PL) and UV Raman spectroscopy are also used to systematically study the P25 photocatalytic process under the Uv-visible light irradiation. It expects to reveal the defects changes within TiO 2 nanoparticles from PALS by comparing the different samples involving pristine, adsorption, degradation and recovery samples, and deeply understand the photocatalytic process.…”