Iron(III)-Based Metal–Organic Frameworks As Visible Light Photocatalysts

Radical Cascade Reaction of Heterocyclic Ketene Aminals with Thiocyanates Promoted by Visible Light: Synthesis of Functionalized Fused 2-Iminothiazolines

Herein, a visible-light-promoted radical cascade cyclization of heterocyclic ketene aminals (HKAs) and thiocyanates was developed to access functionalized fused 2-iminothiazolines. This novel cascade reaction can be realized under only visible-light irradiation without the help of external photocatalysts, oxidants, and additives. These multicomponent cascade reactions demonstrate excellent selectivity for the Z-isomers and ensure the formation of the products only in their isomeric form. Preliminary mechanism investigations demonstrated that HKAs and thiocyanates can form electron donor-acceptor complexes for harvesting the energy of visible light to activate substrates and generate reactive radicals. This protocol can be used for synthesizing various natural-like products such as fused 2-iminothiazolines. This approach demonstrates multiple advantages such as commercially available substrates, convenient operation, environmentally friendly, mild conditions, and an efficient multicomponent reaction (2A + B).

Bimetallic MOF-based electrochemical sensor for determination of paracetamol in spiked human plasma

Metal-organic frameworks (MOFs) with their exceptional properties have the potential to revolutionize the field of electrochemistry and pave the way for new and exciting applications. MOFs is an excellent choice as an active electrocatalyst component in the fabrication of electrochemical sensors. Here, bimetallic NiCo-MOFs, monometallic Ni-MOFs, and Co-MOFs were fabricated to modify the carbon paste electrode. Moreover, the ratio between Co and Ni within the bimetallic MOFs was optimized. Our aim in this work is to synthesize different compositions from bimetallic MOFs and systematically compare their catalytic activity with mono-metallic MOFs on paracetamol. The structure and properties of the 2D NiCo-MOFs were characterized by scanning electron microscope, X-ray photoelectron spectroscopy, Fourier transform infrared, and electrochemical method. Bimetallic Ni0.75Co0.25-MOFs modified carbon paste sensor displayed the optimum sensing performance for the electrochemical detection of paracetamol. A linear response over the range 6.00 × 10- 7 to 1.00 × 10- 4 M with a detection limit of 2.10 × 10- 8 M was obtained. The proposed method was applied to detect paracetamol in spiked human plasma and to determine paracetamol in the presence of its major toxic impurity, p-aminophenol. These findings suggest the considerable potential use of the newly developed sensor as a point-of-care tool for detecting paracetamol and p-aminophenol in the future.

Preparation and characterization of cellulose-chitosan/β-FeOOH composite hydrogels for adsorption and photocatalytic degradation of methyl orange

Biopolymer-based hydrogels have received great attention in wastewater treatment due to their excellent properties, e.g., high adsorption capacity, fast kinetics, reusability and ease of operation. In the present work, cellulose-chitosan/β-FeOOH composite hydrogels were prepared via co-dissolution and regeneration process as well as hydrothermal in situ synthesis of β-FeOOH. Effect of β-FeOOH loading on the properties of the composite hydrogels and the removal efficiency of methyl orange (MO) was investigated. Results showed that β-FeOOH was uniformly loaded onto the hydrogel framework, and the nanoporous structure of composite hydrogels could increase not only the effective contact area between β-FeOOH and the pollutants but also the active sites. Moreover, the increased β-FeOOH loading led to the enhanced MO removal rate under light conditions. When the loading time was extended from 6 h to 9 h, the MO removal rate increased by 21%, which can be mainly due to the photocatalytic degradation. In addition, MO removal rate reached 97.75% within 40 min under optimal conditions and attained 80.81% after five repetitions. The trapping experiment and EPR results indicated that the main active species were hydrogel radicals and holes. Consequently, this work provides an effective preparation approach for cellulose-chitosan/β-FeOOH composite hydrogel with high adsorption and photocatalytic degradation, which would hold great promise for wastewater treatment applications.

Insight into Fe-O-Bi electron migration channel in MIL-53(Fe)/Bi4O5I2 Z-scheme heterojunction for efficient photocatalytic decontamination

Building a heterojunction is a fascinating option to guarantee sufficient carrier separation and transfer efficiency, but the mechanism of charge migration at the heterojunction interface has not been thoroughly studied. Herein, MIL-53(Fe)/Bi4O5I2 photocatalyst with a Z-scheme heterojunction structure is constructed, which achieves efficient photocatalytic decontamination under solar light. Driven by the newly-built internal electric field (IEF), the formation of Fe-O-Bi electron migration channel allows for rapid separation and transfer of charge carriers at the heterojunction interface, confirmed by the material characterization and density functional theory (DFT) calculation. The narrower band gap and improved visible light response also contribute to the enhanced photocatalytic activity of composite materials. With levofloxacin as the target pollutant, the optimal MIL-53(Fe)/Bi4O5I2 achieves complete removal of pollutant within 150 min, the photocatalysis rate of which is ca. 4.4 and 26.0 times that of pure Bi4O5I2 and MIL-53(Fe), respectively. Simultaneously, the optimal composite material exhibits satisfactory photodegradation of seven fluoroquinolones, and the photocatalysis rates are as follows: lomefloxacin > ciprofloxacin > enrofloxacin > norfloxacin > pefloxacin > levofloxacin > marbofloxacin. DFT calculations reveal a positive relationship between degradation rate and Fukui index (ƒ0) of main carbon atoms in seven fluoroquinolones. This study sheds light on the existence of electron migration channels at Z-scheme heterojunction interface to ensure sufficient photoinduced carrier transfer, and reveals the influence of pollutant structure on photolysis rate.

Modifying Parallel Excitations into One Framework for C(sp3)─H Bond Activation with Energy Combined More Than Two Photons

Natural photosynthesis enzymes utilize energies of several photons for challenging oxidation of water, whereas artificial photo-catalysis typically involves only single-photon excitation. Herein, a multiphoton excitation strategy is reported that combines parallel photo-excitations with a photoinduced electron transfer process for the activation of C(sp3)─H bonds, including methane. The metal-organic framework Fe3-MOF is designed to consolidate 4,4',4″-nitrilotrisbenzoic units for the photoactivation of dioxygen and trinuclear iron clusters as the HAT precursor for photoactivating alkanes. Under visible light irradiation, the dyes and iron clusters absorbed parallel photons simultaneously to reach their excited states, respectively, generating 1O2 via energy transfer and chlorine radical via ligand-to-metal charge transfer. The further excitation of organic dyes leads to the reduction of 1O2 into O2 •- through a photoinduced electron transfer, guaranteeing an extra multiphoton oxygen activation manner. The chlorine radical abstracts a hydrogen atom from alkanes, generating the carbon radical for further oxidation transformation. Accordingly, the total oxidation conversion of alkane utilizing three photoexcitation processes combines the energies of more than two photons. This new platform synergistically combines a consecutive excited photoredox organic dye and a HAT catalyst to combine the energies of more than two photons, providing a promising multiphoton catalysis strategy under energy saving, and high efficiency.

Mechanistic study of visible light driven photocatalytic degradation of clofibric acid using Fe-based metal organic frameworks (MOFs)

Although a series of past studies proved the potential usage of Fe-based metal-organic frameworks (MOFs) as photocatalysts, there remains a knowledge gap of the photocatalytic mechanism stemming from the challenge to separate the simultaneous sorption and photocatalytic degradation. Thus, this article aimed to suggest a novel approach by desorbing target molecules during photocatalysis to excavate the underlying mechanisms of sorption and photocatalytic degradation. In this study, two Fe-based MOFs, MIL-101(Fe) and MIL-101(Fe)-NH2, were selected to remove clofibric acid under visible light irradiation. Prior to photocatalysis, sorption mechanism was uncovered based on the sorption kinetic, isotherm, thermodynamic interpretation, and of its dependence on solution pH. The results inferred that the primary sorption mechanism was through the π-π interaction between the benzene ring of clofibric acid and the organic ligand of Fe-based MOFs. Based on these results, photocatalytic mechanism could be independently or jointly assessed during the photocatalytic degradation of clofibric acid. Subsequently, the application of the Tauc method and XPS spectra revealed that the bandgap structure of Fe-based MOFs had the potential to oxidize clofibric acid by producing ROS through the electron excitation upon visible-light illumination. On top of that, the amine functionalization of Fe-based MOF altered the structural moiety that led to an additional strong acid-base interaction with clofibric acid but a decrease in the bandgap limiting the ROS production during photocatalytic activity.

Magnetic FNS/MILs nanofibers for highly efficient removal of norfloxacin via adsorption and Fenton-like reaction

Iron-containing MOFs have attracted extensive interest as promising Fenton-like catalysts. In this work, magnetic Fe3O4 nanofiber (FNS)/MOFs composites with stable structure, included FNS/MIL-88B, FNS/MIL-88A and FNS/MIL-100, were prepared via the in-situ solvothermal method. The surface of the obtained fibers was covered by a dense and continuous MOFs layer, which could effectively solve the agglomeration problem of MOFs powder and improved the catalytic performance. The adsorption and catalytic properties of FNS/MOFs composites were evaluated by removal of norfloxacin. FNS/MIL-88B showed the best performance with a maximum adsorption capacity up to 214.09 mg/g, and could degrade 99% of NRF in 60 min. Meanwhile, FNS/MIL-88B had a saturation magnetization of 20 emu/g, and could be rapidly separated by an applied magnetic field. The self-supported nanofibers allowed the adequate contact between MOFs and pollutants, and promoted the catalytic activity and high stability. We believe that this work provided a new idea for the design and preparation of Fenton-like catalysts especially MOFs composites.

Enhanced optical and electrochemical properties of FeBTC MOF modified TiO2 photoanode for DSSCs application

In this work, iron based 1, 3, 5-tricarboxylic acid (FeBTC) was prepared via microwave-assisted method and incorporated into TiO2 via ultrasonic assisted method. The TiO2-FeBTC nanocomposites were characterized by XRD, FTIR, Raman, BET, FESEM, HRTEM, TGA, UV‒vis DRS and PL to understand their crystallographic, surface morphology, and optical characteristics. The Raman spectra showed a blue shift of Eg, A1g, and B1g peaks upon incorporation of FeBTC MOF onto TiO2. HRTEM and XRD analysis confirmed a mixture of TiO2 nanospheres and hexagonal FeBTC MOF morphologies with high crystallinity. The incorporation of FeBTC onto TiO2 improved the surface area as confirmed by BET results, which resulted in improved absorption in the visible region as a results of reduced bandgap energy from 3.2 to 2.84 eV. The PL results showed a reduced intensity for TiO2-FeBTC (6%) sample, indicating improved separation of electron hole pairs and reduced recombination rate. After fabrication of the TiO2-FeBTC MOF photoanode, the charge transfer kinetics were enhanced at TiO2-FeBTC MOF (6%) with Rp value of 966 Ω, as given by EIS studies. This led to high performance due to low charge resistance. Hence, high power conversion efficiency (PCE) value of 0.538% for TiO2-FeBTC (6%) was achieved, in comparison with other loadings. This was attributed to a relatively high surface area which allowed more charge shuttling and thus better electrical response. Conversely, upon increasing the FeBTC MOF loading to 8%, significant reduction in efficiency (0.478%) was obtained, which was attributed to sluggish charge transfer and fast electron-hole pair recombination rate. The TiO2-FeBTC (6%) may be a good candidate for use in DSSCs as a photoanode materials for improved efficiency.

Fabrication of samarium doped MOF-808 as an efficient photocatalyst for the removal of the drug cefaclor from water

MOFs are emerging photocatalysts designed by tuning organic ligands and metal centers for optimal efficiency. In this study, a samarium decorated MOF-808(Ce) metal organic framework was fabricated by facile hydrothermal synthesis. The synthesized samarium decorated MOF-808(Ce) was characterized by using analytical techniques such as SEM, EDX, XRD and TGA to study its morphological, thermal and structural properties. SEM images showed that MOF-808(Ce) comprised of truncated octahedrons. The morphology of the material was changed upon Sm incorporation. Sm/MOF-808(Ce) exhibited better UV-vis light absorption properties than MOF-808(Ce) as evidenced by its slightly higher band gap value. This material was exploited for the degradation of the drug cefaclor from water. Cefaclor removal followed double a first order in parallel model (DFOP). Under UV light, 97.7% of the cefaclor was removed in only 20 minutes and after 60 minutes this removal efficiency was increased to 99.25%. These features exhibited that samarium decorated MOF has immense potential for the photocatalytic degradation of cefaclor as it generates e- and h+ to enhance the photocatalytic efficiency and it is a promising candidate to treat wastewater without formation of harmful byproducts.

Laser-Ironing Induced Capping Layer on Co-ZIF-L Promoting In Situ Surface Modification to High-Spin Oxide-Carbon Hybrids on the "Real Catalyst" for High OER Activity and Stability

Enhancing electrocatalytic performance through structural and compositional engineering attracts considerable attention. However, most materials only function as pre-catalysts and convert into "real catalysts" during electrochemical reactions. Such transition involves dramatic structural and compositional changes and disrupts their designed properties. Herein, for the first time, a laser-ironing (LI) approach capable of in-situ forming a laser-ironing capping layer (LICL) on the Co-ZIF-L flakes is developed. During the oxygen evolution reaction (OER) process, the LICL sustains the leaf-like morphology and promotes the formation of OER-active Co3 O4 nanoclusters with the highest activity and stability. In contrast, the pristine and conventional heat-treated Co-ZIF-Ls both collapse and transform to less active CoOOH. The density functional theory (DFT) calculations pinpoint the importance of the high spin (HS) states of Co ions and the narrowed band gap in Co3 O4 nanoclusters. They enhance the OER activity by promoting spin-selected electron transport, effectively lowering the energy barrier and realizing a spontaneous O2 -releasing step that is the potential determining step (pds) in CoOOH. This study presents an innovative approach for modulating both structural and compositional evolutions of electrocatalysts during the reaction, sustaining stability with high performance during dynamic electrochemical reactions, and providing new pathways for facile and high-precision surface microstructure control.

Advances in metal-organic frameworks for water remediation applications

Rapid industrialization and agricultural development have resulted in the accumulation of a variety of harmful contaminants in water resources. Thus, various approaches such as adsorption, photocatalytic degradation and methods for sensing water contaminants have been developed to solve the problem of water pollution. Metal-organic frameworks (MOFs) are a class of coordination networks comprising organic-inorganic hybrid porous materials having organic ligands attached to inorganic metal ions/clusters via coordination bonds. MOFs represent an emerging class of materials for application in water remediation owing to their versatile structural and chemical characteristics, such as well-ordered porous structures, large specific surface area, structural diversity, and tunable sites. The present review is focused on recent advances in various MOFs for application in water remediation via the adsorption and photocatalytic degradation of water contaminants. The sensing of water pollutants using MOFs via different approaches, such as luminescence, electrochemical, colorimetric, and surface-enhanced Raman spectroscopic techniques, is also discussed. The high porosity and chemical tunability of MOFs are the main driving forces for their widespread applications, which have huge potential for their commercial use.

Recent Advances in Laser-Induced Synthesis of MOF Derivatives

Metal-organic frameworks (MOFs) are crystalline materials with permanent pores constructed by the self-assembly of organic ligands and metal clusters through coordination bonds. Due to their diversity and tunability, MOFs are used as precursors to be converted into other types of functional materials by pyrolytic recrystallization. Laser-induced synthesis is proven to be a powerful pyrolytic processing technique with fast and accurate laser irradiation, low loss, high efficiency, selectivity, and programmability, which endow MOF derivatives with new features. Laser-induced MOF derivatives exhibit high versatility in multidisciplinary research fields. In this review, first, the basic principles of laser smelting and the types of materials for laser preparation of MOF derivatives are briefly introduced. Subsequently, it is focused on the peculiarity of the engineering of structural defects and their applications in catalysis, environmental protection, and energy fields. Finally, the challenges and opportunities at the current stage are highlighted with the aim of elucidating the future direction of the rapidly growing field of laser-induced synthesis of MOF derivatives.

Empowering Adsorption and Photocatalytic Degradation of Ciprofloxacin on BiOI Composites: A Material-by-Design Investigation

Binary and ternary composites of BiOI with NH2-MIL-101(Fe) and a functionalized biochar were synthesized through an in situ approach, aimed at spurring the activity of the semiconductor as a photocatalyst for the removal of ciprofloxacin (CIP) from water. Experimental outcomes showed a drastic enhancement of the adsorption and the equilibrium (which increased from 39.31 mg g-1 of bare BiOI to 76.39 mg g-1 of the best ternary composite in 2 h time), while the kinetics of the process was not significantly changed. The photocatalytic performance was also significantly enhanced, and the complete removal of 10 ppm of CIP in 3 h reaction time was recorded under simulated solar light irradiation for the best catalyst of the investigated batch. Catalytic reactions supported by different materials obeyed different reaction orders, indicating the existence of different mechanisms. The use of scavengers for superoxide anion radicals, holes, and hydroxyl radicals showed that although all these species are involved in CIP photodegradation, the latter play the most crucial role, as also confirmed by carrying out the reaction at increasing pH conditions. A clear correlation between the reduction of BiOI crystallite sizes in the composites, as compared to the bare material, and the material performance as both adsorbers and photocatalyst was identified.

Relative Local Electron Density Tuning in Metal-Covalent Organic Frameworks for Boosting CO2 Photoreduction

The high local electron density and efficient charge carrier separation are two important factors to affect photocatalytic activity, especially for the CO2 photoreduction reaction. However, the systematic studies on the structure-functional relationship regarding the above two factors based on precisely structure model are rarely reported. Herein, as a proof-of-concept, we developed a new strategy on the evaluation of local electron density by controlling the relative electron-deficient (ED) and electron-rich (ER) intensity of monomer at a molecular level based on three rational-designed vinylene-linked sp2 carbon-covalent organic frameworks (COFs). As expected, the as-prepared vinylene-linked sp2 carbon-conjugated metal-covalent organic framework (MCOFs) (VL-MCOF-1) with molecular junction exhibited excellent activities for CO2 -to-HCOOH conversion (283.41 μmol g-1  h-1 ) and high selectivity of 97.1 %, much higher than the VL-MCOF-2 and g-C34 N6 -COF, which is due to the synergistic effect of the multi-electronic metal clusters (Cu3 (PyCA)3 ) (PyCA=pyrazolate-4-carboxaldehyde) as strong ER roles and cyanopyridine units as ED roles and active sites, as well as the boosted photo-induced charge separation efficiency of vinyl connection and increased light utilization ability. These results not only provide a strategy for regulating the electron-density distribution of photocatalysts at the molecular level but also offers profound insights for metal clusters-based COFs to effective CO2 conversion.

Metal-organic frameworks as photocatalysts in energetic and environmental applications

Metal-organic frameworks (MOFs) are an exciting new class of porous materials with great potential for photocatalytic applications in the environmental and energy sectors. MOFs provide significant advantages over more traditional materials when used as photocatalysts due to their high surface area, adaptable topologies, and functional ability. In this article, we summarize current developments in the use of MOFs as photocatalysts for a variety of applications, such as CO2 reduction, water splitting, pollutant degradation, and hydrogen production. We discuss the fundamental properties of MOFs that make them ideal for photocatalytic applications, as well as strategies for improving their performance. The opportunities and challenges presented by this rapidly expanding field are also highlighted.

Heterogeneous photo-Fenton catalyst α-Fe2O3@g-C3N4@NH2-MIL-101(Fe) with dual Z-Scheme heterojunction for degradation of tetracycline

A novel photo-Fenton catalyst α-Fe2O3@g-C3N4@NH2-MIL-101(Fe) (FGN) with dual Z-scheme heterojunction was successfully prepared by hydrothermal method to degrade tetracycline (TC). The preparation conditions were optimized by orthogonal test, and the successful synthesis was confirmed by characterization analyses. The prepared FGN showed better light absorption performance, higher photoelectrons-holes separation efficiency, lower photoelectrons transfer resistance, and higher specific surface area and pore capacity compared with α-Fe2O3@g-C3N4 and α-Fe2O3. The effects of experimental conditions on the catalytic degradation of TC were investigated. The degradation rate of 10 mg/L TC could reach 98.33% within 2 h when the dosage of FGN was 200 mg/L, and the degradation rate could remain 92.27% after 5 times of reuse. Furthermore, the XRD spectra and XPS spectra of FGN before and after reuse were compared to explore the structural stability and catalytic active sites of FGN, respectively. According to the identification of oxidation intermediates, three degradation pathways of TC were proposed. Through H2O2 consumption experiment, radical-scavenging experiments, EPR results, the mechanism of the dual Z-scheme heterojunction was proved. The improved performance of FGN was attributed to the dual Z-Scheme heterojunction effectively promoting the separation of photogenerated electrons from the holes and accelerating the electrons transfer, and the increase of the specific surface area.

Renaissance of elemental phosphorus materials: properties, synthesis, and applications in sustainable energy and environment

The polymorphism of phosphorus-based materials has garnered much research interest, and the variable chemical bonding structures give rise to a variety of micro and nanostructures. Among the different types of materials containing phosphorus, elemental phosphorus materials (EPMs) constitute the foundation for the synthesis of related compounds. EPMs are experiencing a renaissance in the post-graphene era, thanks to recent advancements in the scaling-down of black phosphorus, amorphous red phosphorus, violet phosphorus, and fibrous phosphorus and consequently, diverse classes of low-dimensional sheets, ribbons, and dots of EPMs with intriguing properties have been produced. The nanostructured EPMs featuring tunable bandgaps, moderate carrier mobility, and excellent optical absorption have shown great potential in energy conversion, energy storage, and environmental remediation. It is thus important to have a good understanding of the differences and interrelationships among diverse EPMs, their intrinsic physical and chemical properties, the synthesis of specific structures, and the selection of suitable nanostructures of EPMs for particular applications. In this comprehensive review, we aim to provide an in-depth analysis and discussion of the fundamental physicochemical properties, synthesis, and applications of EPMs in the areas of energy conversion, energy storage, and environmental remediation. Our evaluations are based on recent literature on well-established phosphorus allotropes and theoretical predictions of new EPMs. The objective of this review is to enhance our comprehension of the characteristics of EPMs, keep abreast of recent advances, and provide guidance for future research of EPMs in the fields of chemistry and materials science.

Asymmetric Supercapacitors Using Porous Carbons and Iron Oxide Electrodes Derived from a Single Fe Metal-Organic Framework (MIL-100 (Fe))

MOF-derived carbon (MDC) and metal oxide (MDMO) are superior materials for supercapacitor electrodes due to their high specific capacitances, which can be attributed to their high porosity, specific surface area (SSA), and pore volume. To improve the electrochemical performance, the environmentally friendly and industrially producible MIL-100 (Fe) was prepared using three different Fe sources through hydrothermal synthesis. MDC-A with micro- and mesopores and MDC-B with micropores were synthesized through carbonization and an HCl washing process, and MDMO (α-Fe₂O₃) was obtained by a simple sintering in air. The electrochemical properties in a three-electrode system using a 6 M KOH electrolyte were investigated. These novel MDC and MDMO were applied to an asymmetric supercapacitor (ASC) system to overcome the disadvantages of traditional supercapacitors, enhancing energy density, power density, and cyclic performance. High SSA materials (MDC-A nitrate and MDMO iron) were selected for negative and positive electrode material to fabricate ASC with KOH/PVP gel electrolyte. As-fabricated ASC resulted in high specific capacitance 127.4 Fg^-1 at 0.1 Ag^-1 and 48.0 Fg^-1 at 3 Ag^-1, respectively, and delivered superior energy density (25.5 Wh/kg) at a power density 60 W/kg. The charging/discharging cycling test was also conducted, indicating 90.1% stability after 5000 cycles. These results indicate that ASC with MDC and MDMO derived from MIL-100 (Fe) has promising potential in high-performance energy storage devices.

The strong interaction and confinement effect of Ag@NH2-MIL-88B for improving the conversion and durability of photocatalytic Cr(VI) reduction in the presence of a hole scavenger

Selectively regulating active factors in photocatalytic reactions by designing materials is one of the very important factors. Herein, we prepared spindle-like core-shell Ag@NH₂-MIL-88B composites (Ag@NM-88) by a two-step hydrothermal method. The as-prepared Ag@NM-88 displayed superior photocatalytic activity for Cr(VI) reduction under LED light, compared with the activities of pure NH₂-MIL-88B (NM-88) and Ag/NM-88 (Ag was deposited on NH₂-MIL-88B). The core-shell structure Ag@NM-88 was not only beneficial to the absorption of light but also beneficial to the separation of photogenerated e^- and h⁺. More importantly, it was further confirmed by active radical capture experiments and nitroblue tetrazolium (NBT) conversion experiments that the design of the core-shell structure could effectively prevent photogenerated e^- from combing with O₂ to form •O₂^-, so that photogenerated e^- directly reduced Cr(VI), thereby improving the reaction rate. In addition, it could still maintain good stability after 5 cycles, indicating that the construction of a core-shell structure is also conducive to improving stability. This work provides a strategy for selectively regulating the active components of photocatalysts, and provides new insights into the relationship between interfacial charge transfer and molecular oxygen activation in photocatalytic reduction Cr(VI) systems.

Graphite oxide as an electronic conductor modified ZIF-8/NH2-MIL-125(Ti) hybrid material used as a photocatalyst for removal of organic dyes under visible light irradiation

It is a great challenge to develop photocatalysts for the degradation of organic pollutants in the aqueous environment, especially those with excellent catalytic performance under visible light conditions. In this work, using graphene oxide (GO) as an electron shuttle agent and carrier, a hybrid of ZIF-8/NH₂-MIL-125(Ti) and GO (ZIF-8/NH₂-MIL-125(Ti)/GO) was prepared by a simple two-step solvothermal method. The morphology, structure, and combination of the synthesized catalysts were studied. The results showed that graphene oxide and ZIF-8 formed an in situ load on NH₂-MIL-125(Ti). The construction of hybrid materials significantly improved the catalytic activity of NH₂-MIL-125(Ti) in the visible light range. The degradation activity of the synthesized catalyst was further tested with reactive red dye. The results showed that the catalyst exhibited excellent catalytic removal efficiency for active red, with a degradation rate of 99.8% within 2 h. The prepared hybrid materials have good application prospects in the field of organic pollutant treatment in water.

Efficient Photocatalytic Degradation of Tetracycline under Visible Light by an All-Solid-State Z-Scheme Ag3PO4/MIL-101(Cr) Heterostructure with Metallic Ag as a Charge Transmission Bridge

The Z-type Ag/Ag₃PO₄/MIL-101(Cr) heterojunction photocatalyst (referred to as AAM-x) was successfully prepared by a simple in situ precipitation method. The photocatalytic activity of the AAM-x samples was evaluated using a common tetracycline (TC) antibiotic. All AAM-x materials are more effective in removing TC than Ag₃PO₄ and MIL-101(Cr). Among them, AAM-3 exhibited efficient photodegradation efficiency and excellent structural stability, and the removal rate of TC (20 mg L^-1) by AAM-3 (0.5 g L^-1) under 60 min of visible light was 97.9%. The effects of photocatalyst dosage, pH, and inorganic anions were also systematically investigated. According to the X-ray photoelectron spectroscopy analysis, metallic silver particles appeared on the surface of the Ag₃PO₄/MIL-101(Cr) mixture during the catalyst synthesis. The results of photoluminescence spectra, photocurrent response, EIS, and fluorescence lifetime showed that AAM-3 has a high photogenic charge separation efficiency. An all-solid-state Z-type heterojunction mechanism including Ag₃PO₄, metallic Ag, and MIL-101(Cr) is proposed to rationalize the excellent photocatalytic performance and photostability of AAM-x composites and to explain the effect of metallic Ag acting as a charge transfer bridge. The TC intermediates were identified using liquid chromatography-mass spectrometry and possible routes of TC degradation were also discussed. This work provides a viable idea for removing antibiotics by an Ag₃PO₄/MOF-based heterogeneous structured photocatalyst.

MIL-101-NH2(Fe)-Coated Nylon Microfibers for Immobilized Photocatalysts in RhB and Cr(VI) Removal

MIL-101-NH₂(Fe) is one of the effective photocatalytic metal-organic frameworks (MOFs) working under visible light. However, its powder-type form inhibits reusability in practical applications. In this study, we immobilized MIL-101-NH₂(Fe) on a polymeric microfiber mesh to improve reusability while minimizing the loss of catalytic performance. To overcome the lack of surface functionality of the nylon fibers, an atomic layer deposition Al₂O₃ layer and NH₂-BDC linker were introduced to facilitate uniform coating of the MOF on the fiber surface. The reactions of the metal precursor to the nylon substrate and NH₂-BDC ligand of the MOF allow chemical bonding from the core to the shell of the entire hybrid catalytic materials. The resulting fiber-immobilized MOFs (Nylon@Al₂O₃@MOF) demonstrated high photocatalytic performance in the removal of RhB and Cr(VI) as representatives of organic dyes and heavy metals, respectively, while retaining over 85% of its efficiency after five cycles.

Polyacrylonitrile@TiO2 nanofibrous membrane decorated by MOF for efficient filtration and green degradation of PM2.5

A systematic study was performed on PM2.5 filtration and photodegradation performance of polyacrylonitrile @TiO₂/ zeolitic imidazolate framework-8（PTZ）hybrid membrane. The hybrid membrane was prepared by electrospinning technique and in situ Metal-organic frameworks (MOFs) synthesis. The optimized membrane maintained a good PM2.5 capture efficiency (greater than 99%) and a pressure drop of 34 Pa. The larger specific surface area and higher pore structure enhance the filter interception effect and electrostatic interaction, which can have high applications for the filtering of PM2.5. In addition, zeolitic imidazolate framework-8 (ZIF-8) is uniformly coated on the surface of polyacrylonitrile @ TiO₂ (PT) nanofiber to form N-Ti-O bonds, thus reducing the reorganization of electron-hole pairs and improving the efficiency of photodegradation. Compared with PT, the hybrid structure formed by PTZ has a higher degradation efficiency for PM2.5 (increased from 66% to 85%). The produced PTZ membrane exhibits a promising future in the collection and green degradation of PM2.5.

Photoexcitation of Fe3 O Nodes in MOF Drives Water Oxidation at pH=1 When Ru Catalyst Is Present

Artificial photosynthesis strives to convert the energy of sunlight into sustainable, eco-friendly solar fuels. However, systems with light-driven water oxidation reaction (WOR) at pH=1 are rare. Broadly used [Ru(bpy)₃ ]²⁺ (bpy=2,2'-bipyridine) photosensitizer has a fixed +1.23 V potential which is insufficient to drive most water oxidation catalysts (WOCs) in acid, while Fe₂ O₃ , featuring the highly oxidizing holes, is not stable at low pH. Here, the key examples of Fe-based metal-organic framework (MOF) water oxidation photoelectrocatalysts active at pH=1 are presented. Fe-MIL-126 and Fe MOF-dcbpy structures were formed with 4,4'-biphenyl dicarboxylate (bpdc), 2,2'-bipyridine-5,5'-dicarboxylate (dcbpy) linkers and their mixtures. Presence of dcbpy linkers allows integration of metal-based catalysts via coordination to 2,2'-bipyridine fragments. Fe-based MOFs were doped with Ru-based precursors to achieve highly active MOFs bearing [Ru(bpy)(dcbpy)(H₂ O)₂ ]²⁺ WOC. Materials were analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infra-red (FTIR) spectroscopy, resonance Raman, X-ray absorption spectroscopy, fs optical pump-probe, electron paramagnetic resonance (EPR), diffuse reflectance and electric conductivity measurements and were modeled by band structure calculations. It is shown that under reaction conditions, Fe^III and Ru^III oxidation states are present, indicating rate-limiting electron transfer in MOF. Fe₃ O nodes emerge as photosensitizers able to drive prolonged O₂ evolution in acid. Further developments are possible via MOF's linker modification for enhanced light absorption, electrical conductivity, reduced MOF solubility in acid, Ru-WOC modification for faster WOC catalysis, or Ru-WOC substitution to 3d metal-based systems. The findings give further insight for development of light-driven water splitting systems based on Earth-abundant metals.

Enzyme-Inspired Coordination Polymers for Selective Oxidization of C(sp3)-H Bonds via Multiphoton Excitation

Nature's blueprint provides the fundamental principles for expanding the use of abundant metals in catalysis; however, mimicking both the structure and function of copper enzymes simultaneously in one artificial system for selective C-H bond oxidation faces marked challenges. Herein, we report a new approach to the assembly of artificial monooxygenases utilizing a binuclear Cu₂S₂Cl₂ cluster to duplicate the identical structure and catalysis of the Cu_A enzyme. The designed monooxygenase Cu-Cl-bpyc facilitates well-defined redox potential that initially activated O₂via photoinduced electron transfer, and generated an active chlorine radical via a ligand-to-metal charge transfer (LMCT) process from the consecutive excitation of the in situ formed copper(II) center. The chlorine radical abstracts a hydrogen atom selectively from C(sp³)-H bonds to generate the radical intermediate; meanwhile, the O₂^•- species interacted with the mimic to form mixed-valence species, giving the desired oxidization products with inherent product selectivity of copper monooxygenases and recovering the catalyst directly. This enzymatic protocol exhibits excellent recyclability, good functional group tolerance, and broad substrate scope, including some biological and pharmacologically relevant targets. Mechanistic studies indicate that the C-H bond cleavage was the rate-determining step and the cuprous interactions were essential to stabilize the active oxygen species. The well-defined structural characters and the fine-modified catalytic properties open a new avenue to develop robust artificial enzymes with uniform and precise active sites and high catalytic performances.

Recent advances in application of metal-organic frameworks (MOFs) as adsorbent and catalyst in removal of persistent organic pollutants (POPs)

The presence of persistent organic pollutants (POPs) in the aquatic environment is causing widespread concern due to their bioaccumulation, toxicity, and possible environmental risk. These contaminants are produced daily in large quantities and released into water bodies. Traditional wastewater treatment plants are ineffective at degrading these pollutants. As a result, the development of long-term and effective POP removal techniques is critical. In water, adsorption removal and photocatalytic degradation of POPs have been identified as energy and cost-efficient solutions. Both technologies have received a lot of attention for their efforts to treat the world's wastewater. Photocatalytic removal of POPs is a promising, effective, and long-lasting method, while adsorption removal of persistent POPs represents a simple, practical method, particularly in decentralized systems and isolated areas. It is critical to develop new adsorbents/photocatalysts with the desired structure, tunable chemistry, and maximum adsorption sites for highly efficient removal of POPs. As a class of recently created multifunctional porous materials, Metal-organic frameworks (MOFs) offer tremendous prospects in adsorptive removal and photocatalytic degradation of POPs for water remediation. This review defines POPs and discusses current research on adsorptive and photocatalytic POP removal using emerging MOFs for each type of POPs.

Room temperature synthesis of monolithic MIL-100(Fe) in aqueous solution for energy-efficient removal and recovery of aromatic volatile organic compounds

The removal and recovery of volatile organic compounds (VOCs) are widely used in many industrials. Unfortunately, most conventional porous materials not only have low VOCs uptake, but also need to be regenerated at relatively high temperature. Metal-organic frameworks (MOFs) have great potential for the removal and recovery of VOCs as their record-breaking gas adsorption capacity, easy regeneration, tunable pore structure and functional groups. Whereas, powdered MOFs are hardly implemented in industrial fields owing to their low bulk density and high pressure drop. Exploring a green method to prepare granular MOFs for the removal and recovery of VOCs is still a challenge. Herein, we report the room temperature green synthesis of a stable Fe-based MOF monolith by using water as the solvent without applying high pressure and chemical binders. The static and dynamic experiments show that the optimized centimeter-scale monolith has high porosity and mechanical strength, and exhibits much better adsorption performance for representative aromatic VOCs (benzene, toluene and p-xylene), than commercial activated carbon and activated carbon fiber under the same conditions. Remarkably, as-synthesized monolith can be rapidly regenerated at lower temperature. These results clearly demonstrate the advantages of MOF monoliths in removing and recovering VOCs, and also provide new insight into the effects of drying temperature, washing and centrifugation procedures on MOF shaping.

Enhancing the spatial separation of photogenerated charges on Fe-based MOFs via structural regulation for highly-efficient photocatalytic Cr(VI) reduction

Although iron-based metal-organic frameworks (Fe-MOFs) have displayed the photocatalytic activity, there is still abundant room for improving their photocatalytic performance through tuning the structures. In this work, four novel iron-based metal-organic frameworks (Fe-MOFs) were successfully synthesized via ligand modulation for better photocatalytic Cr(VI) reduction, in which MTBDC-TPT-Fe had the highest catalytic activity (MTBDC = 2,5-bis(methylthio)terephthalic acid, TPT = 2,4,6-tri(4-pyridyl)- 1,3,5-triazine). The boosted photocatalytic reduction may be mainly ascribed to the enhanced electron push-pull effect between iron-oxygen clusters and organic ligands. The introduction of -SCH₃ groups can enhance the light absorption and donate electrons to iron center under visible-light irradiation, meanwhile the separation and transfer of photogenerated charge carriers can be enhanced resulting from the electron-pulling effect when introducing TPT. Moreover, enhanced specific surface areas and positive skeleton charge due to the introduction of TPT may improve active sites exposure and Cr(VI) adsorption, thereby enhancing photocatalytic Cr(VI) reduction activity without the presence of any assisted scavengers. In addition, the photocatalytic mechanism (i.e. active species) were also studied and presented. This work confirmed an effective structure-performance regulation strategy on Fe-MOFs for photocatalytic Cr(VI) reduction.

Rational Design of a Core-Shell Structured Plasmonic Au@MIL-100(Fe) Nanocomposite for Efficient Photocatalysis

The utilization of solar light to trigger organic syntheses for the production of value-added chemicals has attracted increasing recent research attention. The integration of plasmonic Au NPs (NPs = nanoparticles) with MOFs would provide a new way for the development of highly efficient photocatalytic systems. In this manuscript, a bottle-around-ship strategy was adopted for the successful synthesis of a core-shell structured Au_pvp@MIL-100(Fe) (PVP = polyvinylpyrrolidone) nanocomposite in room temperature. The as-obtained core-shell structured Au_pvp@MIL-100(Fe) show improved photocatalytic performance for benzyl alcohol oxidation under visible light, because of the migration of the surface plasmon resonance (SPR) excited hot electrons from plasmonic Au NPs to MIL-100(Fe), resulting in the production of more active O₂^•- radicals. The removal of the capping agent PVP from Au_pvp@MIL-100(Fe) significantly enhanced the photocatalytic performance, because of an improved charge transfer from plasmonic Au NPs to MIL-100(Fe). This study demonstrates an efficient strategy of fabricating superior photocatalytic systems by a rational coupling of plasmonic Au NPs and photocatalytic active MOFs into a core-shell structured nanocomposite.

ZIF-8 metal organic framework composites as hydrogen evolution reaction photocatalyst: A review of the current state

In the past decade, extensive research has been devoted to synthesis of ZIF-8 materials for catalytic applications. As physico-chemical properties are synthesis-dependent, this review explores different synthesis strategies based the solvent and solvent-free synthesis of zeolitic imidazole framework. Accordingly, the effect of several parameters on the ZIF-8 synthesis were discussed including solvent, deprotonating agents, precursors ratio is delivered. Additionally, the advantages and disadvantages of each synthesis have been discussed and assessed. ZIF-8 textural and structural properties justify its wide use as a stable high surface area MOF in aqueous catalytic reactions. This review includes the applicatios of ZIF-8 materials in photocatalytic hydrogen evolution reaction (HER). The efficiency of the reviewed materials was fairly assessed. Finally, Limitations, drawbacks and future challenges were fully debated to ensure the industrial viability of the ZIFs.

Saiz P, Reizabal A, Wuttke S, Celaya-Azcoaga L, Valverde A, Fernández de Luis R. A State-of-the-Art of Metal-Organic Frameworks for Chromium Photoreduction vs. Photocatalytic Water Remediation

Hexavalent chromium (Cr(VI)) is a highly mobile cancerogenic and teratogenic heavy metal ion. Among the varied technologies applied today to address chromium water pollution, photocatalysis offers a rapid reduction of Cr(VI) to the less toxic Cr(III). In contrast to classic photocatalysts, Metal-Organic frameworks (MOFs) are porous semiconductors that can couple the Cr(VI) to Cr(III) photoreduction to the chromium species immobilization. In this minireview, we wish to discuss and analyze the state-of-the-art of MOFs for Cr(VI) detoxification and contextualizing it to the most recent advances and strategies of MOFs for photocatalysis purposes. The minireview has been structured in three sections: (i) a detailed discussion of the specific experimental techniques employed to characterize MOF photocatalysts, (ii) a description and identification of the key characteristics of MOFs for Cr(VI) photoreduction, and (iii) an outlook and perspective section in order to identify future trends.

Improved visible light photocatalytic nitrogen fixation activity using a FeII-rich MIL-101(Fe): breaking the scaling relationship by photoinduced FeII/FeIII cycling

The scaling relations between nitrogen adsorption and NH_x destabilization are key challenges to the widespread adoption of the photocatalytic synthesis of ammonia. In this work, a Fe^II-rich MIL-101(Fe) (MIL-101(Fe^II/Fe^III)) was synthesized using a one-step solvent thermal method with ethylene glycol (EG) as a reducing agent, which can break the scaling relationship by photoinduced Fe^II (high nitrogen adsorption ability) and Fe^III (high NH_z destabilization ability) cycling. XPS was used to detect the change in iron valence state in the MIL-101(Fe^II/Fe^III) material. The photocatalytic nitrogen fixation efficiency of MIL-101(Fe^II/Fe^III) under visible light without any sacrificial agent was 466.8 μmol h^-1 g^-1, five times that of MIL-101(Fe). After photocatalytic experiments, MIL-101(Fe^II/Fe^III) retained an unchanged Fe^II/Fe^III rate, indicating that this Fe^II/Fe^III cycling can be maintained. DFT modeling of the Fe^II-rich MOF material showed that a FeII1 FeIII2 system has a higher N₂ activation capacity than a FeIII3 system. The catalytic mechanism was further proved by in situ infrared spectra and N¹⁵ isotopic tracers. Therefore, the improvement of photocatalytic activity was mainly attributed to the change in the nitrogen adsorption capacity during the photoinduced Fe^II/Fe^III cycling.

A novel SERS substrate of MIL-100(Fe)/AgNFs for sensitive detection of ascorbic acid in cellular media

A novel SERS substrate of MIL-100(Fe)/AgNFs was firstly prepared for sensitive and selective detection of ascorbic acid (L-AA), with a LOD of 10-11 M. A spectral decrease of MIL-100(Fe)/AgNFs towards L-AA solution thanks to the efficient capture and reduction of Fe3+ in MIL-100(Fe) constituted the assay, which was demonstrated to function well in food samples and in cellular media for L-AA sensing.

Highly luminescent scintillating hetero-ligand MOF nanocrystals with engineered Stokes shift for photonic applications

Large Stokes shift fast emitters show a negligible reabsorption of their luminescence, a feature highly desirable for several applications such as fluorescence imaging, solar-light managing, and fabricating sensitive scintillating detectors for medical imaging and high-rate high-energy physics experiments. Here we obtain high efficiency luminescence with significant Stokes shift by exploiting fluorescent conjugated acene building blocks arranged in nanocrystals. Two ligands of equal molecular length and connectivity, yet complementary electronic properties, are co-assembled by zirconium oxy-hydroxy clusters, generating crystalline hetero-ligand metal-organic framework (MOF) nanocrystals. The diffusion of singlet excitons within the MOF and the matching of ligands absorption and emission properties enables an ultrafast activation of the low energy emission in the 100 ps time scale. The hybrid nanocrystals show a fluorescence quantum efficiency of ~60% and a Stokes shift as large as 750 meV (~6000 cm⁻¹), which suppresses the emission reabsorption also in bulk devices. The fabricated prototypal nanocomposite fast scintillator shows benchmark performances which compete with those of some inorganic and organic commercial systems.

The development of highly luminescent materials such as large Stokes shift fast emitters is desirable for their potential application in photonics. Here the authors engineer hetero-ligand metal-organic frameworks nanoparticles to achieve high emission yield, large Stokes shift and realize a prototypal fast scintillator.

Simplified creation of polyester fabric supported Fe-based MOFs by an industrialized dyeing process: Conditions optimization, photocatalytics activity and polyvinyl alcohol removal

MIL-53(Fe) was successfully prepared and deposited on the surface carboxylated polyester (PET) fiber by an optimized conventional solvothermal or industrialized high temperature pressure exhaustion (HTPE) process to develop a PET fiber supported MIL-53(Fe) photocatalyst (MIL-Fe@PET) for the degradation of polyvinyl alcohol (PVA) in water under light emitting diode (LED) visible irradiation. On the basis of several characterizations, MIL-Fe@PET was tested for the photocalytic ability and degradation mechanism. It was found that temperature elevation significantly enhanced the formation and deposition of MIL-53(Fe) with better photocatalytic activity. However, higher temperature than 130°C was not in favor of its photocatalytic activity. Increasing the number of surface carboxyl groups of the modified PET fiber could cause a liner improvement in MIL-53(Fe) loading content and photocatalytic ability. High visible irradiation intensity also dramatically increased photocatalytic ability and PVA degradation efficiency of MIL-Fe@PET. Na₂S₂O₈ was used to replace H₂O₂ as electron acceptor for further promoting PVA degradation in this system. MIL-Fe@PET prepared by HTPE process showed higher MIL-53(Fe) loading content and slightly lower PVA degradation efficiency than that prepared by solvothermal process at the same conditions. These findings provided a practical strategy for the large-scale production of the supported MIL-53(Fe) as a photocatalyst in the future.

Encapsulation-Led Adsorption of Neutral Dyes and Complete Photodegradation of Cationic Dyes and Antipsychotic Drugs by Lanthanide-Based Macrocycles

Molecular architectures offering large cavities can accommodate guest molecules, while their compositional engineering allows tunability of the band gap to support photocatalysis using visible light. In this work, two lanthanide (Ln)-based macrocycles, synthesized using a cobalt-based metalloligand and offering large rectangular cavities, exhibited selective adsorption of neutral dyes over both anionic and cationic dyes. Both Ln macrocycles illustrated complete photodegradation of cationic dyes using visible light without the use of any oxidant. Both Ln macrocycles exhibited complete photodegradation of not only cationic dyes but also a few phenothiazine-based antipsychotic drugs. Photocatalysis involved the generation of reactive oxygen species (ROS), which was corroborated with the band gap of two Ln macrocycles. These results were supported by radical scavenger studies and the quantitative estimation of superoxide and hydroxyl radicals. Complete photodegradation of both dyes and drugs was confirmed by spectral studies, while the generation of CO₂ and N₂ gases was established by gas chromatography. Importantly, Ln macrocycles were able to distinguish between the neutral dyes that were quantitatively adsorbed and the cationic dyes/drugs that were completely photodegraded.

Room-temperature preparation of highly efficient NH2-MIL-101(Fe) catalyst: The important role of -NH2 in accelerating Fe(III)/Fe(II) cycling

The slow redox rate of Fe(III)/Fe(II) couples is a rate-limiting step for Fenton-like performance of Fe-MOFs. In this study, a series of catalysts (MIL-101) with various p-phthalic acid/2-aminoterephthalic acid (H₂BDC/NH₂-H₂BDC) molar ratios were prepared using a simple and mild chemical method and applied for catalyzed degradation of bisphenol A (BPA). Interestingly, the -NH₂ modified MIL-101(Fe) can adjust Fe-Oxo node by increasing the electron density of Fe(III) in the presence of -NH₂ group with high electron density, thus forming Fe(II) in situ in MOFs. Meanwhile, the -NH₂ groups used as electron-donors can promote electron transfer, resulting in faster Fe(III)→Fe(II) half-reaction and active H₂O₂ to continuously generate •OH radical. The BPA degradation and rate constant of Fe-BDC-NH₂/H₂O₂ system are 15.4-fold and 86.8-fold higher than that of Fe-BDC/H₂O₂ system, respectively. The density functional theory (DFT) calculations showed that Fe-BDC-NH₂ possesses higher Fermi level energy (-4.88 eV) and lower activation energy barriers (0.32 eV) compared with Fe-BDC. Moreover, Fe-BDC-NH₂ showed good reusability and stability. This work offers a highly efficient and stable MOFs-based Fenton-like catalyst to rapidly degrade organic pollutants over a wide pH range for potential applications in wastewater treatment.

Green synthesis of MIL-100(Fe) derivatives and revealing their structure-activity relationship for 2,4-dichlorophenol photodegradation

MIL-100(Fe), a kind of iron-based metal-organic framework materials (MOFs), can be synthesized at room temperature or hydrothermal conditions, which are promising precursor materials for preparing photocatalysts to degrade some recalcitrant chlorophenols in industrial wastewater. However, the relationship between the structural characterization of MIL-100(Fe) derivatives and their photodegradation behavior of chlorophenol pollutants is still unclear. Thus, in this work, a porous Z-scheme α-Fe₂O₃/MIL-100(Fe) composite was successfully fabricated via partial-pyrolysis of MIL-100(Fe) precursor synthesized through green synthesis route, which was further used for degrading high-concentration of 2,4-dichlorophenol under visible-light illumination (λ > 420 nm). The effects of synthesis route and pyrolysis temperature of MIL-100(Fe) on the degradation efficiencies of as-derived materials for 2,4-dichlorophenol were investigated. The structure-activity relationship was illuminated in detail. Otherwise, the influence of several process factors, i.e., initial concentration and pH of the 2,4-dichlorophenol solution, catalyst dosage on the degradation efficiency of 2,4-dichlorophenol has also been performed. The removal efficiency of 2,4-dichlorophenol with the initial concentration of 100 mg L^-1 reached up to 87.65% under optimized conditions. Lastly, the possible mechanism was explored based on trapping experiments and some other characterization results. The study in this paper not only exhibited new insight into the modified α-Fe₂O₃ material with high photocatalytic activity but also provided a promising method for treating wastewater containing 2,4-dichlorophenol or other similar organic pollutants.