The Existence of Nitrate Radicals in Irradiated TiO2 Aqueous Suspensions in the Presence of Nitrate Ions

Preparation of a benziodazole-type iodine(III) compound and its application as a nitrating reagent for synthesis of furazans via a copper-catalyzed cascade process

The existing hypervalent I(III) reagents bearing ONO2 group are limited in types and their applications primarily focused on the nitrooxylation reactions featuring a fully-exo fashion. Herein, a benziodazole-type O2NO-I(III) compound was prepared and its reaction with β-monosubstituted enamines in the presence of CuI could trigger a radical nitration/cyclization/dehydration cascade to provide a series of less explored but biologically interesting furazan heterocycles. Mechanistically, the benziodazole-type O2NO-I(III) compound acts as a nitrating reagent and incorporates its NO moiety into the final furazan product in a fully-endo model, a process of which was proposed to involve nitration, cyclization and dehydration.

Fabrication of Electrode Material for Textile-Based Triboelectric Nanogenerators: Research of the Relationship between Output Performance and Dielectric Material Strain

In this work, a textile-based triboelectric nanogenerator (TENG) device was developed through electroless plating technology to prepare electrode material. Hydrophilic groups on the fiber surface are able to absorb Ag+, which could play a role in the center of a catalyst to reduce Cu2+ to fabricate Cu-coated cotton toward the fabrication of TENG electrode material. The TENG device established admirable performance and good stabilization, and a maximum voltage at 9.6 V was detected when the stress and strain on the polydimethylsiloxane layer are 82.6 kPa and 5.8%, respectively. In addition, the relationships among device properties and strain/thickness of dielectric materials have been explored in depth as well. The output voltage of the device increases gradually with the enhancement of dielectric strain and stress. As expected, the TENG as-fabricated device was installed to various physical behaviors to illustrate the harvesting of power of knee-jerk movements.

Preparation of metal-free BP/CN photocatalyst with enhanced ability for photocatalytic tetracycline degradation

The successful application of photocatalysis in practical water treatment opreations relies greatly on the development of highly efficient, stable and low-cost photocatalysts. The low-cost metal-free photocatalyst made up of black phosphorus (BP) and graphitic carbon nitride (CN) was successfully constructed and firstly used for the photocatalytic treatment of antibiotic contaminants in this work. Compared with bare CN, the BP/CN photocatalyst exhibited the enhanced photocatalytic performance for tetracycline hydrochloride (HTC) degradation, that 99% of HTC was removed by 6BP/CN (doping amount of BP was 6%) within 30 min under the simulated visible-light irradiation. The efficiency was even comparable to those of some high-efficiency photocatalysts recently-reported such as Fe⁰@POCN, CuInS₂/Bi₂MoO₆ and Cu₂O@HKUST-1. Under natural sunlight illumination, the determined apparent rate constant for degradation of HTC by BP/CN was 2.7 times as that by P25 TiO₂. The experimental results indicated that loading BP on CN could enhance the separation of charge carriers and promote the ability of light absorption for visible-light, thus leading to a greater catalytic activity. Meanwhile, the influences of different operating variables (pH, water, ion and HTC concentration) on HTC degradation were studied in detail. Furthermore, the degradation pathway of HTC was also proposed. In addition, the photocatalytic activity of the BP/CN for production of hydrogen peroxide (H₂O₂) was also studied, which could reach up to 501.04 μmol g^-1h^-1. It is anticipated that BP/CN photocatalyst could be used for practical water treatment.

Mutual influence of cupric cations and several anions in anatase and rutile TiO2 photocatalysis

Copper ions in aqueous solution are known to promote organic oxidation in semiconductor photocatalysis, but the counter anions seem to be important as well. In this work, the performance of Cu(ClO₄)₂ in presence of several anions in sodium forms (F^-, Cl^-, ClO₄^-, NO₃^-, and SO₄^2-) has been examined. Phenol oxidation in aqueous solution (pH 4) under UV light was used as model reaction and TiO₂ in the forms of anatase (AT) and rutile (RT) as photocatalysts. On the addition of 0.1-5 mM Cu²⁺, the reactions on AT and RT all increased. On the addition of 1 mM anions, reactions on AT increased by F^-and SO₄^2-, but reactions on RT all decreased. In presence of 3 mM Cu²⁺, however, reactions on AT and RT all decreased by 1 mM anions except NO₃^-. Such anion effects were also observed for H₂ production on AT and RT in presence of Cu²⁺ and 10% methanol. A possible mechanism for the positive and negative anion effects is discussed. This work indicates that the formation of a Cu(II)/Cu(I) complex with anions weakens the positive effect of copper ions on organic oxidation in TiO₂ photocatalysis.

Photocatalytic degradation of tetracycline antibiotics using delafossite silver ferrite-based Z-scheme photocatalyst: Pathways and mechanism insight

Tetracycline (TC), a widely used antibiotic, is easy to enter the aquatic ecosystem through soil erosion, livestock manure and wastewater discharge, resulting in a series of risks. The application of Z-scheme photocatalysts with efficient interface charge separation and transfer has been regard as an effective strategy for antibiotic degradation. Herein, a novel ternary Z-scheme Bi₁₂O₁₇Cl₂/Ag/AgFeO₂ was successfully synthesized by ultrasound-assisted ethanol reduction of Ag⁺ on the interface of Bi₁₂O₁₇Cl₂ and AgFeO₂. The Bi₁₂O₁₇Cl₂/Ag/AgFeO₂ Z-scheme system exhibited an enhanced photocatalytic degradation capability for TC, which was over 6.5 times and 2.4 times higher than those of AgFeO₂ and Bi₁₂O₁₇Cl₂/AgFeO₂ system, respectively. The photocatalytic process of TC was explored, and the results indicated that an optimum catalyst concentration of 0.5 g L^-1 and a primeval pH (without adjustment) favored the degradation process, while the introduction of exogenous anions (CO₃^2-, SO₄^2- and NO₃^-) and organic matter (HA) supressed the degradation of TC. Simultaneously, the possible pathway for the degradation process of TC was presented based on the liquid chromatography-mass spectrometry (LC-MS) analysis. Active species trapping experiments and ESR spectra revealed the significant contribution of O₂^- in the TC degradation, and verified the Z-scheme mechanism of the Bi₁₂O₁₇Cl₂/Ag/AgFeO₂ system.

Features and application of coupled cold plasma and photocatalysis processes for decontamination of water

Dielectric barrier discharge plasma and photocatalysis have been proposed as tools for decontamination of process water, especially in food industry. The present investigation aims to redefine and identify the features of coupling the two technologies in terms of degradation efficiency of a model compound. Results show that, when the process is carried out in plasma activated water in the presence of irradiated TiO₂, the efficiency of the integrated process is lower than the sum of the two processes acting separately. It is proposed that afterglow species, e.g. hydrogen peroxide and/or peroxynitrites could be activated by UVA light irradiation producing hydroxyl radicals in the liquid phase. Even if TiO₂ limits this additional effect by acting as UVA screen barrier material, its decontamination efficiency under certain conditions results higher than that obtained with plasma systems. These results open the route to chlorine-free decontamination processes and redefine the application framework of this integrated approach.