Particularities of photocatalysis and formation of reactive oxygen species on insulators and semiconductors: cases of SiO₂, TiO₂and their composite SiO₂–TiO₂

Abstract

Highly defected tubular SiO2 outperforms the photocatalytic activity of TiO2-P25 and the SiO2–TiO2 composite.

Highly active ZnO-based biomimetic fern-like microleaves for photocatalytic water decontamination using sunlight

“…The determination of the formation of hydroxyl radicals, oxygen superoxide, and singlet oxygen by salt (Sigma-Aldrich) by the oxygen superoxide. The oxygen singlet was determined by using the highly selective Singlet Oxygen Sensor Green reagent (Invitrogen) by measuring the reduction in the absorbance peak of a 5 mM methanol solution at 517 nm, due to the highly selective reaction between the anthracene part of this reagent and the singlet oxygen [52]. A quartz cuvette with an optical length of 1 cm using a UV-1800 Shimadzu UV-vis spectrophotometer (Shimadzu Corporation) was used to determine both oxygen superoxide and singlet oxygen formation.…”

“…The mineralization of pollutants is possible due to the fact that the additional charge carriers (e -/h + ) and reactive oxygen species, such as superoxide and hydroxyl radicals, are generated on the photocata- Figure S18) [52]. The kinetics of hydroxyl formation in the absence of photocatalyst have also been considered, since the photolysis of water, which is especially relevant under UV irradiation, can also be an important source of hydroxyl radicals.…”

Hybrid Ni@ZnO@ZnS‐Microalgae for Circular Economy: A Smart Route to the Efficient Integration of Solar Photocatalytic Water Decontamination and Bioethanol Production

“…However, oxygen superoxide ions (O 2 − ) and singlet oxygen ( 1 O 2 ) can also play an important role; this role drastically depends on the pH. [4,10] Specifically, the kinetics and concentration of hydroxyl radicals was investigated using a fluorescein salt as the selective radical quencher, assuming zero order kinetics and equimolar reaction stoichiometry between hydroxyl radicals and fluorescein molecules. [4,10] Specifically, the kinetics and concentration of hydroxyl radicals was investigated using a fluorescein salt as the selective radical quencher, assuming zero order kinetics and equimolar reaction stoichiometry between hydroxyl radicals and fluorescein molecules.…”

SiO2-Based Materials for Immobilization of Enzymes

“…The catalytic [9] and photocatalytic [10] activities of platinum-modified SiO 2 nanotubes and spheres were further investigated and proven to be dependent on morphology of SiO 2 matrix which bears (supports) the metallic active phase. SiO 2 veils have been also obtained, and their composites have been used as support for platinum electrocatalyst [11].Improvement of in situ generated template-assisted SiO 2 synthesis and appropriate post-synthesis treatments allowed us to obtain nanotubes with intrinsic photo-and electrochemical activity due to high density of oxygen-related lattice defects [12,13] but also to reveal the distinctive capacity of highly defected SiO 2 and its composite SiO 2 -TiO 2 to generate reactive oxygen species (ROS) with potential applications in biology and medicine [14].SiO 2 materials (nanotubes) have been proven to be biologically active for bioremediation processes, showing bactericidal and bacteriostatic effects on halotolerant microorganisms [15]. These type of materials have been successfully used as inorganic carriers in hybrid complex with enzymes [16], the enzymatic activity of the complex being dependent on morphological and textural properties of SiO 2 matrices [17].Generally, sol-gel synthesis of tubular SiO 2 materials was conducted in line with Nakamura and Matsui's work [18], modifications of synthetic procedure being done in respect to particular applications.Thin and larger SiO 2 nanotubes in addition to spherical SiO 2 are meant to function as inorganic host for immobilized enzymes, and, accordingly, their previously synthesis has been reported [7,17].…”

“…Improvement of in situ generated template-assisted SiO 2 synthesis and appropriate post-synthesis treatments allowed us to obtain nanotubes with intrinsic photo-and electrochemical activity due to high density of oxygen-related lattice defects [12,13] but also to reveal the distinctive capacity of highly defected SiO 2 and its composite SiO 2 -TiO 2 to generate reactive oxygen species (ROS) with potential applications in biology and medicine [14].…”