Turn-on fluorescence determination of sulfide based on site-occupying modulation of MOF-copper nanocluster interaction

A tunable interaction between Fe-MOFs (MIL-53(Fe) and kojic acid (KA)-functional copper nanoclusters (Cu NCs) has been studied. When introducing MIL-53(Fe), the Fe-O bonds can be formed between the KA on the surface of Cu NCs and MIL-53(Fe), which will induce the electron transfer from Cu NCs to MIL-53(Fe) and fluorescence quenching of Cu NCs. By introducing S^2- it occupies the Fe-site of MIL-53(Fe) and impede the interaction between Cu NCs and MIL-53(Fe), rendering a "turn-on" fluorescence signal. Thus, the KA-Cu NC/MIL-53(Fe) pair is designed as fluorescence sensing for S^2-, which displays a low detection limit of 18.6 nM and a wide linear detection range from 0.05 to 5 µM by fitting the fluorescence intensity at maximum wavelength of 500 nm with excitation at 400 nm. It was also applied to monitor S^2- in water samples and food additives with satisfactory results, demonstrating the practicability and reliability of the sensing strategy based on the tuable MOF-Cu NC interactions.

Recent advances in photodegradation of antibiotic residues in water

Antibiotics are widely present in the environment due to their extensive and long-term use in modern medicine. The presence and dispersal of these compounds in the environment lead to the dissemination of antibiotic residues, thereby seriously threatening human and ecosystem health. Thus, the effective management of antibiotic residues in water and the practical applications of the management methods are long-term matters of contention among academics. Particularly, photocatalysis has attracted extensive interest as it enables the treatment of antibiotic residues in an eco-friendly manner. Considerable progress has been achieved in the implementation of photocatalytic treatment of antibiotic residues in the past few years. Therefore, this review provides a comprehensive overview of the recent developments on this important topic. This review primarily focuses on the application of photocatalysis as a promising solution for the efficient decomposition of antibiotic residues in water. Particular emphasis was laid on improvement and modification strategies, such as augmented light harvesting, improved charge separation, and strengthened interface interaction, all of which enable the design of powerful photocatalysts to enhance the photocatalytic removal of antibiotics.

A binary MOF of iron and copper for treating ciprofloxacin-contaminated waste water by an integrated technique of adsorption and photocatalytic degradation

A novel MIL 53(Fe–Cu) was synthesized by a solvothermal process. This binary metal organic framework removed ciprofloxacin from waste water.

Co3O4/Bi4O5I2/Bi5O7I C-Scheme Heterojunction for Degradation of Organic Pollutants by Light-Emitting Diode Irradiation

Remediation of organic pollutant matrixes from wastewater by photodegradation using different heterojunctions is extensively studied to improve performance for potential application. Brilliant black (BB) and p-nitrophenol (PNP) have been detected in the environment and implicated as directly or indirectly carcinogenic to human health. This work analyzes their elimination from aqueous solutions under visible-light irradiation with composites of cobalt(II, III) oxide and bismuth oxyiodides (Co₃O₄/Bi₄O₅I₂/Bi₅O₇I). The synthesized nanomaterial properties were investigated using various techniques such as BET, SEM/EDS, TEM, XRD, FTIR, PL, and UV-vis. All the nanocomposites absorbed in the visible range of the solar spectrum with band gaps between 1.68 and 2.79 eV, and the specific surface area of the CB2 composite increased by 35.8% from that of Bi₄O₅I₂/Bi₅O₇I. There was an observed massive reduction in the rate of electron and hole recombination, and the band gaps of the composites decreased. The mineralization of PNP and BB was followed by determination of the total organic carbon with reductions of 93.6 and 83.7%, respectively. The main active species were the hydroxyl radicals, while the superoxide anion radical and generated holes were minor as confirmed by radical trapping experiments. The optimum pHs for degradation of PNP and BB were 9.6 and 5.3, respectively. The enhanced performance of the catalyst was due to C-scheme heterojunction formation that reduced the electron and hole recombination rate and was attributed to strong adsorption of the pollutants on the photocatalyst active surface. The nanocomposite is apposite for solar energy-driven remediation of organic pollutants from environmental aqueous samples.

A nine-fold enhancement of visible-light photocatalytic hydrogen production of g-C3N4 with TCNQ by forming a conjugated structure

Photocatalytic hydrogen evolution by water splitting has become a very effective way to solve the energy crisis. For use in that process, graphitic carbon nitride (g-C₃N₄) has drawn much attention for its response in the visible region. However, its insufficient sunlight absorption efficiency and easy recombination of photoinduced carriers restrict its photocatalytic activity. Herein, we demonstrate a two-step liquid ultrasonic method in water to synthesize a series of tetracyanoquinodimethane (TCNQ)-C₃N₄ photocatalysts aiming to form a conjugated structure by 7,7,8,8-TCNQ. g-C₃N₄ was treated with APTES firstly on its surface in order to give a better interface contact with TCNQ. Benefiting from the conjugation effect between TCNQ and g-C₃N₄, the separation and transport efficiency of photogenerated carriers were significantly improved. Besides, introducing TCNQ also broadened the absorption region. Both of these points lead to the enhancement of photocatalytic H₂ production rate, with the optimized 5% TCNQ-C₃N₄ giving a rate nearly 9.48 times that of pure g-C₃N₄. Also, 5% TCNQ-C₃N₄ (U) was prepared with unmodified g-C₃N₄, which exhibited a rate only 6.87 times that of pure g-C₃N₄, thus validating the necessity of surface modification. Our work reveals that the rational conjugated structure could modulate the electrical and optical properties of g-C₃N₄, yielding an improvement of photocatalytic activities.

Recent advances in MOF-based photocatalysis: environmental remediation under visible light

Highly photoactive MOFs can be engineered via various strategies for the purpose of extended visible light absorption, more efficient generation, separation and transfer of charge carriers, as well as good recyclability.

The facile boosting sunlight-driven photocatalytic performance of a metal–organic-framework through coupling with Ag2S nanoparticles

A facile method was successfully developed to tremendously boost sunlight-driven photocatalytic performance of a MOFs material (MIL-53(Fe)) by coupling with silver sulfide (Ag₂S) nanoparticles for the first time.

Engineering nanomaterials for water and wastewater treatment: review of classifications, properties and applications

Based on their characteristics and applicability, a new category of NMs is proposed for water and wastewater treatment.

A tetraphenylporphyrin/WO3/exfoliated graphite nanocomposite for the photocatalytic degradation of an acid dye under visible light irradiation

Charge carrier separation in visible light photocatalytic degradation of a dye was achieved by the fabrication of a tetraphenylporphyrin/WO₃/exfoliated graphite nanocomposite.

Ferroelectric enhanced Z-scheme P-doped g-C3N4/PANI/BaTiO3 ternary heterojunction with boosted visible-light photocatalytic water splitting

Surface polarization promotes the charge separation efficiency of PCN/PANI/BTO ternary heterojunction, resulting in an enhanced visible-light photocatalytic hydrogen production activity.