Search

Chemically bonded Z-scheme ZnSnO 3 /AgI composites rich in oxygen vacancies (OVs) and Lewis acid sites were prepared successfully and showed excellent photocatalytic activities. Especially, ZnAg-2 degraded 96.1% tetracycline under visible light irradiation for 15 min. OVs contributed to Lewis acid sites production and interfacial chemical bonds formation through weakening the metal−O bonding. Lewis acid sites favored the adsorption of electron-rich tetracycline. Interfacial chemical bonds together with Z-scheme structure accelerated electron transfer and retained the high redox ability of ZnSnO 3 and AgI. OVs contributed to singlet oxygen (1O 2) production through facilitating the energy transfer from triplet exciton to O 2. ZnSnO 3 /AgI composites possess good reusability and show great practical application potential. Based on ROSs generation and photoreduction experiment, the photocatalytic mechanism of the ZnAg composites was proposed. The possible degradation pathway was deduced and the biological toxicity was evaluated based on detected degradation intermediates. This work highlights the significant roles of OVs, Lewis acid sites, and chemical bonding in improving the photocatalytic activity of Z-scheme composites and provides new insight into designing high efficient photocatalysts. [Display omitted] • ZnAg-2 composite degraded 96.1% tetracycline under visible light for 15 min. • OVs helped form interfacial chemical bonds and produce 1O 2. • More Lewis acid sites in ZnAg-2 contributed to tetracycline adsorption. • The interfacial chemical bonds acted as "channels" to promote charge transfer. • Z-scheme structure and OVs boosted ROSs generation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Z-scheme InVO 4 /CuBi 2 O 4 /BiVO 4 composites were fabricated with hydrothermal synthesis. • Interfacial Bi O bonds boosted the charge transfer from InVO 4 and BiVO 4 to CuBi 2 O 4. • O vacancies brought by orthovanadates enhanced 1O 2 production through energy transfer. • InVO 4 /CuBi 2 O 4 /BiVO 4 showed good photocatalytic activity for tetracycline degradation. • The composite had good reusability, stability, and performed well in natural water. Dual Z-scheme InVO 4 /CuBi 2 O 4 /BiVO 4 (CuInBi) composites with rich oxygen vacancies and chemical bonds at the heterojunction interfaces were fabricated, for the first time, through hydrothermal method with post annealing treatment, in which CuBi 2 O 4 acts as a bridge to connect InVO 4 and BiVO 4. The as-prepared composites exhibited superior photocatalytic activity compared with the individual semiconductors. Specifically, the degradation rate of tetracycline (20 mg/L) in the presence of CuInBi-1 (1.0 g/L) was up to 5.4, 2.8, and 3.1 times faster than those in the presence of CuBi 2 O 4 , InVO 4 , and BiVO 4 , respectively. The enhanced photocatalytic performance could be partially attributed to the good light absorption of CuBi 2 O 4 , which broadens the visible light response of the InVO 4 /CuBi 2 O 4 /BiVO 4 composites. Meanwhile, the interfacial chemical bonds in the dual Z-scheme heterojunction help accelerate charge separation and maintain strong redox activity. In addition, the oxygen vacancies, induced mainly by the low-valent vanadium atoms, facilitate the production of singlet oxygen (1O 2) through energy transfer, which easily attacks the electron-rich groups, including phenolic group, dimethylamino group, amine group, and double bonds, in tetracycline. The InVO 4 /CuBi 2 O 4 /BiVO 4 composite exhibited excellent reusability and stability, and performed well in photocatalytic degradation of tetracycline in river water and under natural sunlight, demonstrating great potential for practical application. The probable photocatalytic mechanism of InVO 4 /CuBi 2 O 4 /BiVO 4 composite was proposed according to the results of density functional theory (DFT) calculations, and the reactive oxygen species (ROSs) and major degradation intermediates detected in the photocatalytic system. This work demonstrates the important roles of oxygen vacancies and interfacial chemical bonds in boosting the photocatalytic activity of Z-scheme heterojunctions and provides a reference for the construction of high-activity photocatalysts for efficient degradation of antibiotics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hollow tubular In 2 O 3 /AgI photocatalysts with oxygen vacancies were synthesized. • A BIEF with e- flowing from AgI to In 2 O 3 helps the formation of Z-scheme structure. • In 2 O 3 /AgI (2:1, molar) performed well as a photocatalyst for tetracycline degradation. • 1O 2 , h+, •O 2 −, and •OH were the key reactive species in the photocatalytic system. • In 2 O 3 /AgI photocatalysts exhibited excellent structural stability and reusability. A novel In 2 O 3 /AgI heterojunction, which has a hollow tubular structure with AgI particles distributed evenly on the outer and inner surfaces of In 2 O 3 microtubes, was fabricated from annealing of AgI adhered to MIL-68(In). The as-prepared heterojunction exhibited much higher photocatalytic activity towards tetracycline degradation compared to In 2 O 3 and AgI. The presence of InAg-1 (1.0 g/L), which has a In 2 O 3 :AgI mole ratio of 2:1, could achieve 98.4% removal of tetracycline (20 mg/L) from the solution phase under visible light illumination in 10 min, and it had excellent reusability and stability. The In 2 O 3 /AgI heterojunction also exhibited excellent performance in photocatalytic degradation of tetracycline in different types of water matrices and under natural sunlight illumination, demonstrating its potential in practical application. The superior photocatalytic activity of InAg-1 is attributed to the heterojunction formation and generation of oxygen vacancies (OVs), which improve the separation efficiency of photoinduced e−-h+ pairs. Meanwhile, the built-in electric field (BIEF) formed with e- flowing from AgI to In 2 O 3 , which is confirmed by density functional theory calculations, helps the formation of a Z-scheme, instead of type II, heterojunction between In 2 O 3 and AgI. Results of radical trapping experiments and electron spin resonance spectra reveal that 1O 2 , h+, •O 2 −, and •OH were the key reactive species involved in the photocatalytic degradation process. These findings indicate that Z-scheme photocatalysts with OVs could efficiently activate molecular oxygen and thus have excellent photocatalytic activity towards degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

Large-scale magnetic Co nanoparticles/N-doped carbon nanotubes (Co@NCNTs) hybrids have been designed by pyrolyzing the mixture of cobalt nitrate and melamine for microwave (MW)-induced tetracycline (TC) degradation. The results demonstrated that Co@NCNTs-5, annealed from cobalt nitrate and melamine (mole ratio: 1:5), possessed a good MW absorption ability, resulting in excellent degradation performance towards TC. Specifically, 99.5 % TC (20 mg/L, natural pH) could be removed after 6 min of MW irradiation (520 W) in the presence of Co@NCNTs-5. Meanwhile, Co@NCNTs-5 exhibited competitive degradation efficiency over TC at various concentrations (20–100 mg/L) and pH values (3−8). Results of reusability experiments identified the magnetic recovery ability and stability of Co@NCNTs-5. Based on free radical experiments and electron paramagnetic resonance (EPR) results, HO• and O 2 − • radicals participated in the catalytic degradation process. The degradation pathway of TC was proposed with the assistance of ultrahigh-performance liquid chromatography-mass spectrometry (UPLC-MS). This work develops a facile, low-cost and large-scale method to synthesize Co@NCNTs, which demonstrates great potential in MW-induced catalytic treatment of antibiotic pollutants as high-efficient catalysts. • Low-cost and scalable synthesis of Co@NCNTs was realized. • 99.5 % tetracycline was degraded by microwave using Co@NCNTs-5 within 6 min. • O 2 − • and HO• radicals played a vital role in the microwave catalytic system. • Co@NCNTs-5 exhibited good magnetic retrievability. • Good reusability and stability of Co@NCNTs-5 were proved. [ABSTRACT FROM AUTHOR]

• Common iron (hydr)oxides could promot transformation of TC under sunlight irradiation. • Production of HO• and phototransformation of TC were controlled by H 2 O 2 generation. • H 2 O 2 was produced through a two-electron reduction pathway on crystalline Hem and Goe. • H 2 O 2 was produced through O 2 reduction and Fe2+ oxidation on poorly crystalline Fh. • TC phototransformed faster under alkaline conditions in presence of iron (hydr)oxides. Iron (hydr)oxides are abundant in surface environment, and actively participate in the transformation of organic pollutants due to their large specific surface areas and redox activity. This work investigated the transformation of tetracycline (TC) in the presence of three common iron (hydr)oxides, hematite (Hem), goethite (Goe), and ferrihydrite (Fh), under simulated sunlight irradiation. These iron (hydr)oxides exhibited photoactivity and facilitated the transformation of TC with the initial phototransformation rates decreasing in the order of: Hem > Fh > Goe. The linear correlation between TC removal efficiency and the yield of HO• suggests that HO• dominated TC transformation. The HO• was produced by UV-induced decomposition of self-generated H 2 O 2 and surface Fe2+-triggered photo-Fenton reaction. The experimental results indicate that the generation of HO• was controlled by H 2 O 2 , while surface Fe2+ was in excess. Sunlight-driven H 2 O 2 production in the presence of the highly crystalline Hem and Goe occurred through a one-step two-electron reduction pathway, while the process was contributed by both O 2 -induced Fe2+ oxidation and direct reduction of O 2 by electrons on the conduction band in the presence of the poorly crystalline Fh. These findings demonstrate that sunlight may significantly accelerate the degradation of organic pollutants in the presence of iron (hydr)oxides. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • NH 2 -MIL-53(Al) as modulator enhances fluorescence dual-emission of TpTt-COF. • Benzene ring of the probe recognizes tetracycline through π-π interactions. • Fluorescence quenching via N/O of the probe and −OH/−NH 2 of tetracycline. • Limit of detection of 0.014 μmol/L and recoveries of 94.39–105.67% are achieved. • The optosmart sensing system is applied to visual detection of tetracycline. Tetracycline residues in animal-derived food pose serious harm to human health, making it demanded to develop simple and sensitive method for detecting tetracycline. Herein, a dual-emission synchronous response fluorescence probe is reported based on amino-functionalized Al-MOF modulated TpTt-COF (donate as NMT). NMT exhibits excellent dual-emission at 455 and 575 nm under single excitation. Tetracycline is sensitively detected through quenching the dual-emission of NMT. NMT specifically recognizes tetracycline through intermolecular hydrogen bonding between –OH/−NH 2 of tetracycline and deprotonated O−/−NH−/C N of NMT. A calibration curve is built between the fluorescence ratio and the tetracycline concentration with a detection limit of 0.014 μmol/L. NMT is employed to detect tetracycline in milk, pork and chicken, and displays satisfactory recoveries of 94.39–105.67%, respectively. The optosmart sensor based on NMT and smartphone has been constructed for visually detecting tetracycline. This method provides routes to construct MOF-COF fluorescence probes and has good prospects in food analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • NH 2 of UiO-66-NH 2 covalent bonding linkage with CHO of TpTt-COF. • UiO-66-NH 2 attenuates the aggregation-caused quenching effect of TpTt-COF. • Benzene ring of TpTt-COF and tetracycline interact recognition by π-π stacking. • Fluorescence quenching via N/O of UiO-66-NH 2 @TpTt-COF and OH/ NH 2 of tetracycline. • LOD of 7.4 nmol/L and recoveries of 88.58–104.31% are achieved. Tetracycline residues are seriously hazardous to environment, it's urgent to develop sensors to detect tetracycline for environmental monitoring. A fluorescence sensor based on dual-emissions UiO-66-NH 2 @TpTt-COF (donate as UNT) composite is constructed by an interfacial growth method for detecting tetracycline. The import of UiO-66-NH 2 attenuates the aggregation-caused quenching (ACQ) of TpTt-COF, which endows UNT emitting strong dual-emissions of 452 nm and 575 nm. Tetracycline is recognized by UNT through π-π stacking and interacts with triazine N and deprotonated O of UNT through intermolecular hydrogen bonds. These interactions impede the excited state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT), and promote the photoinduced electron transfer (PET), inducing synchronous fluorescent quenching of the dual-emissions of UNT. The synchronous response of UNT enhances the specificity and displays excellent sensitivity toward tetracycline with a detection limit of 7.4 nmol/L. UNT is applied for the detection of tetracycline in soil and river water with recoveries of 92.96–98.44% and 88.58–104.31%, respectively. An optosmart sensing system has also been developed to enable visual detection of tetracycline. This work provides a novel synchronous response sensor for antibiotic detection and opens a new path for core-shell MOF@COF composites in the field of environmental monitoring. [ABSTRACT FROM AUTHOR]