Search

• The 3D flower-like MoS 2 /UiO-66 were prepared by in-situ hydrothermal method. • The photocatalytic effect of 20 mg L−1 OTC reached 86.6 % after 120 min irradiation. • The degradation paths were deduced by theoretical and experimental research. • The ∙O 2 − were the main active species on oxytetracycline degradation. • Carrier directed migration and Z-type heterojunction both promote photocatalysis. MoS 2 has potential in the photocatalytic degradation. The combination of UiO-66 (University of Oslo) and MoS 2 not only accelerates the electron transfer efficiency but also increases active sites, thereby further improves the photocatalytic activity. The three-dimensional flower-like MoS 2 /UiO-66 heterojunctions were prepared by in-situ hydrothermal method, which took advantage of metal-organic framework and semiconductor material. Oxytetracycline degradation was used to assess the photocatalytic performance, and the effects of catalyst dosage and solution pH on the performance were looked into. MoS 2 nanosheets formed three-dimensional flower-like spheres on the surface of UiO-66 particles as they expanded in all directions. The unique structure exposed more active sites and provided sufficient surface reaction sites for the reactants. The composite had a broad-spectrum light response, and the oxytetracycline degradation efficiency reached 86.6 % after 120 min' irradiation. The band structure and density of states of MoS 2 were calculated. The possible degradation paths were deduced by theoretical calculation and experimental detection. This excellent photodegradation can be attributed to the fact that Z-type heterojunction promoted the separation of photogenerated electron-hole pairs, prolonged the carrier lifetime, and generated more active substances. In addition, the cyclic test showed that the composite material had good repeatability and potential application prospect. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel nanocomposite Ag 3 PO 4 /BiNbO 4 has been synthesized by a co-precipitation method under mild condition. The properties of the materials such as the crystallinity, the morphology, the light absorption range and photocurrent response intensity have been examined by various instruments. Compared with Ag 3 PO 4 or BiNbO 4 nanomaterials, the as-synthesized Ag 3 PO 4 /BiNbO 4 photocatalysts exhibit excellent photocatalytic performances for photodegradation of Rhodamine B. Effects of different conditions on photocatalytic degradation have been considered, including doping ratio, pollutant concentration and pH. When the content of BiNbO 4 is 10%, the Ag 3 PO 4 /BiNbO 4 nanocomposite shows the satisfied effect. The 98.8% RhB (20 mg/L) can be removed within 30 min in pH 6 under simulated sunlight irradiation. The degradation rate constant is 0.1459 min−1, around 3.63 and 31.02 times than that by Ag 3 PO 4 and BiNbO 4 , respectively. It is on account of the fact that the heterojunction formed by Ag 3 PO 4 and BiNbO 4 promotes the electron-hole separation and improves photocatalytic ability. The possible photocatalytic degradation mechanism was discussed based on the active species, band structures as well as reaction processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The novel composite Bi 2 MoO 6 /NH 2 -UiO-66(Zr/Ce) were synthesized successfully. • The degradation percentage of OTC reached 93.7 % after 150 min irradiation. • The Ce4+/Ce3+ cycle in mixed-metal MOFs improved the charge separation efficiency. • The Z-scheme heterojunction accelerated the charge transfer and photodegradation. • The possible degradation pathway and mechanism were proposed. In this study, Bi 2 MoO 6 /NH 2 -UiO-66(Zr/Ce) photocatalytic materials with heterojunction structure were synthesized by the hydrothermal method, and their photocatalytic degradation of oxytetracycline was researched. All of the composites exhibited better photocatalytic degradation properties than the pristine component. BMNU-2 showed the optimal photodegradation efficiency of 93.7 % after 150 min illumination, with the kinetic constant 7.22 and 3.37 times higher than that of NH 2 -UiO-66(Zr/Ce) and Bi 2 MoO 6 , respectively. The intermediates and degradation pathways of oxytetracycline were investigated by combining intermediate products testing and theoretical calculations. The ·O 2 –, h+ and ·OH are all the vital active species, and the degradation mechanism of oxytetracycline have been thoroughly investigated based on energy band theory. The toxicity test was conducted to investigate the environmental effect of OTC and the intermediates. The outstanding photocatalytic efficiency is mainly owing to three reasons: (1) The introduction of Ce in mixed-metal MOFs minished the band gap of the MOFs; (2) The Ce4+/Ce3+ cycle improved the charge separation efficiency; (3) The formation of heterojunction accelerated the charge transfer and expanded the extension of light absorption. This research offers neoteric thinking for the design of high-performance photocatalytic materials. [ABSTRACT FROM AUTHOR]

Broadening the light absorption and inhibiting carrier's recombination are vital to the improvement of photocatalytic performance. Herein, self-assembly 3D hierarchical microsphere BiOIO 3 /Bi 5 O 7 I Z-scheme heterojunction with carrier transfer channel was firstly fabricated by in-situ solvothermal method. The degradation efficiency for bisphenol A (BPA) reached 98.9 % within 60 min visible light irradiation. The enhanced photocatalytic activity was benefited from the Z-scheme system assisted by iodate/iodide (IO 3 -/I-) as carrier transfer channel that not only accelerated the interfacial charge separation, but also provided massive reactive centers for obtaining high redox capacity. The vulnerable sites and the degradation pathways of BPA were identified by density functional theory calculations and liquid chromatography-mass spectrometry analyses. The toxicity of BPA and its intermediates were predicted by ECOlogical Structure Activity Relationship (ECOSAR) and the results demonstrated that BPA was eventually mineralized to harmless products. The Z-scheme charge transfer mechanism was deeply elucidated based on the role of active species (·O 2 - , ·OH and h+), band structure and carrier separation efficiency. This study provides a promising strategy for the photoactivity enhancement of bismuth based heterojunction in environment purification. [Display omitted] • The 3D hierarchical BiOIO 3 /Bi 5 O 7 I Z-scheme heterojunction was firstly prepared. • The redox mediator IO 3 -/I- directed from BiOIO 3 to Bi 5 O 7 I assisted charge transfer. • The enhancement of BPA degradation (98.9 %) profited from strong redox capacity. • Reaction pathways included hydroxylation, C-C cleavage, oxidation and ring cleavage. • The toxicity and mechanisms were elucidated by ECOSAR program and DFT study. [ABSTRACT FROM AUTHOR]

Photocatalytic oxidation technique is considered as one of the most prospective approaches to solve the problem of environmental pollution. Herein, the novel ternary nanocomposite UiO-66(Ce)/Ag/BiOBr was fabricated via simple synthetic strategy. The obtained UiO-66(Ce)/Ag/BiOBr exhibited an excellent performance and photocatalytic efficiency of ketoprofen reached 93.5% after 180 min illumination. The ·OH and ·O 2 - were main active species and play an important role during the photocatalytic reaction. Furthermore, intermediate products and degradation pathways of ketoprofen were analyzed based on the 3D-EEM, DFT calculation and LC-MS. The possible reaction mechanism was proposed as follows: (1) the successful construction of heterojunction broadened the light absorption range to the visible light region; (2) the design of Ce-based MOFs provided more chances for electron transfer due to the Ce4+/Ce3+ cycling; (3) the combination of plasmon resonance effect, Schottky junction and effect of Ag bridge was an important strategy to accelerate charge transfer and improve photocatalytic efficiency. [Display omitted] • Novel ternary nanocomposite UiO-66(Ce)/Ag/BiOBr has been successfully synthesized. • UiO-66(Ce)/Ag/BiOBr has excellent catalytic performance for ketoprofen degradation. • The design of Ce-based MOFs provided more chances for e−-h+ transfer. • The combined action of SPR, Schottky junction and Ag bridge promoted e− migration. • The possible degradation pathway and reaction mechanism were proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel Z-scheme heterojunction Ag/NH 2 -MIL-125(Ti)/CdS has been synthesized. • The material has large specific surface area, good stability and catalytic ability. • The degradation percentage of ketoprofen reached 94.2% after 180 min illumination. • The Z-scheme heterojunction was favorable for the separation of e- - h+ pairs. • The electron conduction of Ag in the composite was important on the photodegradation. In this study, the Z-scheme heterojunction photocatalysts Ag/NH 2 -MIL-125(Ti)/CdS (AMC-5, AMC-10 and AMC-20) were first successfully obtained by stepwise deposition of Ag and CdS. The morphology, crystallinity and photochemical properties of the materials were investigated. The N 2 adsorption–desorption isotherm showed that AMC-10 had a large specific surface area (363.41 m2/g). Cyclic tests proved that the heterojunction exhibited good stability. In comparison, AMC-10 exhibited a significantly higher photocatalytic activity. Results suggested that 94.2% ketoprofen (10 mg/L) can be photocatalytically degraded to intermediates and small molecules after 180 min of simulated sunlight illumination. AMC-10 had a large degradation rate constant 0.0168 min−1, which is 3.15 and 2.50 times higher than that of CdS and NH 2 -MIL-125(Ti), respectively. The total organic carbon removal percentage of ketoprofen was 57.5%. Free radical trapping experiments indicated that ·O 2 − and h+ were the main active species, which can also be verified by the detection of electron paramagnetic resonance. Possible degradation pathways and reaction mechanisms were proposed by band potential calculations and liquid chromatography-mass spectrometry. The results of Vibrio qinghaiensis sp. -Q67 culture demonstrated that the biotoxicity of ketoprofen increased first and then decreased with time. It can be concluded that the Z-scheme heterojunction of Ag/NH 2 -MIL-125(Ti)/CdS was beneficial for the separation of photo-generated electrons and holes and the noble metal Ag nanoparticles play the important role in the photocatalytic degradation with the surface plasmonic resonance effect and Schottky junction. [ABSTRACT FROM AUTHOR]

• A novel ZnNb 2 O 6 /g-C 3 N 4 material has been prepared by calcination-hydrothermal method. • About 95.7% 2,4-DCP can be degraded under 180 min simulated sunlight irradiation. • The photocatalytic mechanism was discussed through active species and band structure. • The photocatalytic mechanism of Z-scheme heterojunction was proposed. • The h+ and ·O 2 − played the major roles on 2,4-DCP degradation. In view of the deterioration of the environment and the shortage of resources, it is necessary to develop efficient photocatalysts for the degradation of organic pollutants. Herein, a novel and environmentally friendly ZnNb 2 O 6 /g-C 3 N 4 heterojunction nanocomposite was synthesized by calcination-hydrothermal method successfully. The chemical and physical capabilities of the material were characterized by various kinds of analytical instruments. Compared with ZnNb 2 O 6 and g-C 3 N 4 , ZnNb 2 O 6 /g-C 3 N 4 showed the strongest photocatalytic activity. The nanomaterial was used in the removal of the pollutant 2,4-DCP. The effects of degradation conditions were discussed including component ratio, material dosage, initial analyte concentration, pH and salinity. After 180 min' simulated sunlight illumination, the removal efficiency of 2,4-DCP (10 mg/L) reached 95.7% under the optimum condition. Furthermore, the possible photocatalytic mechanisms were discussed according to four aspects: (i) The conformation of the active species; (ii) The calculation of valence and conduction band; (iii) The analysis Z-scheme heterojunction mechanism; (iv) The speculation of feasible photocatalytic paths. In conclusion, the ZnNb 2 O 6 /g-C 3 N 4 (ZC-7) nanocomposite has the least recombination rate of electron-hole pairs and the highest photocatalytic efficiency. [ABSTRACT FROM AUTHOR]