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

Band gap regulation of MIL-101(Fe) via pyrazine-based ligands substitution for enhanced visible-light adsorption and its photo-Fenton-like application

Regulating the photo-response region of iron metal-organic frameworks (Fe-MOFs) is a viable strategy for enhancing their practical application in the visible-light driven photo-Fenton-like process. This study developed a novel pyrazine-based Fe-MOFs (MIL-101(Fe)-Pz) by substituting the 1,4-dicarboxybenzene acid ligands in typical MIL-101(Fe) with 2,5-pyrazinedicarboxylic acid (PzDC), in which sodium acetate was used as coordinative modulator to control the crystal size (2-3 µm). The incorporation of Fe-pyridine N coordination structures originated from PzDC ligands gave MIL-101(Fe)-Pz narrowed band gap (1.45 eV) than MIL-101(Fe) (2.54 eV) resulting in improved visible-light adsorption capacity (λ > 420 nm), and also increased the proportion of Fe(II) in the Fe-clusters. Thus MIL-101(Fe)-Pz exhibited a synergistic enhanced photo-Fenton-like catalytic performance under visible-light irradiation. The MIL-101(Fe)-Pz/H2O2/Vis system could degrade 99% of sulfamethoxazole within 30 min, which was 10-fold faster than that of the pristine MIL-101(Fe), it also effectively removed other organic micropollutants with high durability and stability. Mechanistic analysis revealed that the PzDC ligands substitution decreased the band gap of MIL-101(Fe), giving MIL-101(Fe)-Pz appropriate band structure (-0.40∼1.05 V vs. NHE) which can cover several light-driven process for the generation of reactive oxygen species, including Fe(III) reduction and H2O2 activation for accelerating •OH generation, as well as oxygen reduction reaction for generating H2O2, O2•- and 1O2. This study highlights the role of pyridine-N containing ligands in regulating the band structure of Fe-MOFs, providing valuable guidance for the design of Fe-MOFs photocatalysts.

Ce-modified NH2-MIL-88B enhances catalytic ozonation for effective antibiotic degradation

A Ce-doped NH2-MIL-88B(Fe) composite (Ce-NM8B) was synthesized via a hydrothermal method and used to catalyze ozone oxidation to degrade levofloxacin (LEF) in water. Moreover, comprehensive characterization of Ce-NM8B, including crystal structure, surface morphology, and electrochemical properties, was performed using XRD, SEM, BET, XPS, FT-IR, and ICP techniques. As a result, the Ce-NM8B/O3 system achieved an 84.2 % degradation of 10 mg/L LEF within 40 min under optimal conditions (0.20 g/L catalyst dosage, 0.20 L/min ozone flow, pH 7). Furthermore, EPR and radical quenching experiments confirmed the generation of ·OH, O2·-, and 1O2 species, in addition to direct ozone oxidation and catalytic adsorption. Additionally, HPLC-MS analysis identified key degradation pathways, including piperazine, quinolone, and morpholine ring cleavage, alongside decarboxylation, defluorination, and demethylation. In terms of toxicity, evaluation using T.E.S.T. revealed that intermediate products exhibited reduced toxicity. Moreover, Ce-NM8B demonstrated stable performance over three cycles. Finally, the system's applicability and practical potential were confirmed through the degradation of several antibiotics and testing in natural water substrates.

Surface Oxygen Vacancy Engineering for Enhanced Volatile Organic Compounds Removal in Solar-Interfacial Water Evaporation

Solar-interfacial water-vapor conversion has emerged as a promising method for clean water production, particularly in water-scarce regions, but a major challenge is the volatile organic compounds (VOCs) along with water vapor, leading to polluted condensed water. This study introduces a novel design strategy that leverages surface oxygen vacancies (OVs) in photocatalysts to maximize both oxygen (O2) utilization from the air and photocarrier efficiency at the air-water interface, building upon previous research that demonstrated that oxygen concentration at the interface can be significantly higher than that in bulk water. By enhancing oxygen adsorption and facilitating charge carrier separation, OVs significantly improve reactive oxygen species (ROS, including ·O2- and ·OH) generation and overall photocatalytic activity. As a demonstration, the surface OVs-engineered BiOCl-based photocatalytic solar interfacial evaporator demonstrated a 3.41-fold increase in VOC (phenol) removal efficiency compared to a conventional system, achieving over 99.6% VOC removal in condensed water and maintaining a high water vapor generation flux of 1.90 kg/m2/h. This innovative design was further validated using ZnO-based photocatalysts, demonstrating the broad applicability of OV-engineering in interfacial systems. By fully utilizing both the high oxygen content at the air-water interface and improving photocarrier dynamics, this approach represents a significant advancement in photocatalytic water treatment technologies, offering a scalable and highly efficient solution for VOC removal and clean water production.

Bifunctional photocatalyst/hydrogel composites: Synergistic effects and degradation mechanisms for the degradation of benzo(a)pyrene in smoked sausages

Benzo(a)pyrene (B(a)P) is a structurally stable and carcinogenic compound, and B(a)P deposition and transport from smoking environment particulates to smoked meat products is a global challenge. In this study, a novel photosensitive bifunctional composite gel (ST/SiO2-Mn) was successfully synthesized as a reliable material for reducing PM2.5-B(a)P in the smoke environment. B(a)P removal experiments demonstrated that the adsorption and filtration properties of the gel effectively reduced the emission of PM2.5-B(a)P in smoke environment. The ST/SiO2-Mn gel removed 88.5 % of PM2.5-B(a)P in 240 min, which further led to a 59.7 % decrease in B(a)P on the sausage surface. In addition, photocatalytic experiments demonstrated that the ST/SiO2-Mn composite could effectively remove B(a)P, and 50 μg/mL B(a)P could be completely degraded within 20 min. Free radical trapping experiments showed that superoxide radicals (•O2-) contributed significantly to the degradation process. In conclusion, this study provides valuable insights for effective PM2.5-B(a)P degradation without increasing economic burden.

Structural modification of defective WO3 by g-C3N4 for photocatalytic gold recovery from non-cyanide-based plating effluent

A set of nCN/WO3 - x composites was synthesized through a simple thermal treatment for gold recovery from the simulated effluent of a non-cyanide-based plating bath. The obtained results exhibited that all nCN/WO3 - x composites demonstrated a higher photocatalytic activity for gold recovery than their pristine components due to the formation of nanocomposites which paved a convenient pathway for charge transfer. Among all synthesized composites, the 5.0CN/WO3 - x composite exhibited the highest photocatalytic activity, recovering around 69.4% of gold within 120 min under UV-vis light irradiation at an intensity of 3.45 mW/cm² and a catalyst loading of 1.0 g/L, in the absence of hole scavenger. This result can be ascribed to the presence of an optimal number of defects, which can act as electron trapping sites and thereby reduce the recombination rate of charge carriers. Gold recovery increased with repeated reuse, attributed to the decorated gold, which enhances light absorption and decreases the recombination rate of charge carriers. The feasible application of used CN/WO3 - x were also explored for H2 production, dye degradation and gold recovery. The obtained results provide a new insight about the photocatalytic recovery of gold from industrial wastewater and also shed light on the application of gold-decorated CN/WO3 - x as a catalyst for other photocatalytic applications.

Development and Performance of a PANI@NiMnO3 Nanocomposite for Enhanced Supercapacitors and Photocatalytic Applications

Conductive polymers are gaining considerable attention as a potential material for supercapacitor electrodes due to their favorable properties. Among these, polyaniline (PANI) stands out as a cost-effective and easy to synthesize, making it a promising candidate for improving energy storage applications. This study presents the synthesis of a hybrid composite consisting of PANI and NiMnO3 (NMO) perovskite using the chemical oxidative polymerization method. The morphology and structure of the composite were analyzed by using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. XRD results showed that the addition of NMO transformed the amorphous structure of PANI into a semicrystalline form, leading to enhanced conductivity. SEM images revealed a more uniform and compact structure, with NMO distributed unevenly within the polymer matrix. Optical analysis indicated that a reduction in the band gap of PANI@NMO reached 2.5 eV. N2 adsorption-desorption measurements confirmed an increase in the surface area and pore volume. The photocatalytic activity of the PANI@NMO nanocomposite was tested by degrading methylene blue (MB) dye under UV/visible light. The nanocomposite showed high efficiency, degrading 87.75% of MB dye after 125 min of irradiation as compared to their counter parts. Additionally, electrochemical tests demonstrated an improved electrochemical performance of the composite due to enhanced crystallinity, increased surface area, and reduced electron-hole recombination rate. These results suggest that the PANI@NMO nanocomposite has great potential for use in supercapacitors and photocatalysis.

Metal-Organic Frameworks for Sustainable Crop Disease Management: Current Applications, Mechanistic Insights, and Future Challenges

Efficient management of crop diseases and yield enhancement are essential for addressing the increasing food demands due to global population growth. Metal-organic frameworks (MOFs), which have rapidly evolved throughout the 21st century, are notable for their vast surface area, porosity, and adaptability, establishing them as highly effective vehicles for controlled drug delivery. This review methodically categorizes common MOFs employed in crop disease management and details their effectiveness against various pathogens. Additionally, by critically evaluating existing research, it outlines strategic approaches for the design of drug-delivery MOFs and explains the mechanisms through which MOFs enhance disease resistance. Finally, this paper identifies the current challenges in MOF research for crop disease management and suggests directions for future research. Through this in-depth review, the paper seeks to enrich the understanding of MOFs applications in crop disease management and offers valuable insights for researchers and practitioners.

Controllable fabrication of SbxBi2-xS3 solid solution photocatalysts with superior elimination for Cr(VI)

The development of environmentally friendly and cost-effective photocatalysts is of vital significance for the effective removal of heavy metal contamination in water, but it is still a crucial challenge. Herein, the novel SbxBi2-xS3 solid solution photocatalysts with a certain amount of sulfur vacancy were prepared by adjusting the molar ratio of Sb to Bi through a simple hydrothermal strategy, and was applied to the effective photocatalytic reduction of hexavalent chromium (Cr(VI)). Sb1.75Bi0.25S3 with optimized ratio has superior reduction performance of Cr(VI), and the photocatalytic efficiency of Cr(VI) can achieve 91.9 % within 1 h of visible light illumination. The remarkable catalytic efficiency is due to the more applicable band structure of the solid solution photocatalyst, which is conducive for the photocatalytic reaction. Moreover, the substitution of Bi causes the crystal distortion of Sb2S3 and induce the generation of sulfur defects, which can effectively capture photoelectrons, accelerate the carriers separation, and improve the reduction performance. This study provides a hopeful photocatalyst for wastewater purification and promotes the exploration of solid solution photocatalyst in water environment remediation.

Novel Ag@NH2-UiO-66(Zr) photocatalyst with controllable charge transfer pathways for efficient Cr(VI) remediation

Rational fabrication of core-shell photocatalysts to hamper the charge recombination is extraordinarily essential to enhance photocatalytic activity. In this work, core-shell Ag@NH2-UiO-66 (Ag@NU) Schottky heterojunctions with low Ag content (1 wt%) were constructed by a two-step solvothermal method and adopted for Cr(VI) reduction under LED light. Typically, the one with the Ag: NH2-UiO-66 mass ratio (1 : 100) led to 100% Cr(VI) removal within 1 h, superior to bare NH2-UiO-66 and Ag/NH2-UiO-66 (Ag was directly decorated on NH2-UiO-66 surface). The enhanced photocatalytic activity was related to the migration of the electrons on the CB of NH2-UiO-66 to Ag NPs through a Schottky barrier, and thus the undesired charge carriers recombination was avoided. This result was also evidenced by Density functional theory (DFT) calculations. The computational simulations indicate that the introduction of Ag effectively narrowed the band gap of NH2-UiO-66, facilitating the transfer of photo-generated electrons, expanding the light absorption area, and significantly enhancing photocatalytic efficiency. Most importantly, such a core-shell structure can inhibit the formation of •O2-, letting the direct Cr(VI) reduction by photo-excited e-. In addition, this structure can also protect Ag from being oxidized by O2. Ten cyclic tests evidenced the Ag@NU had excellent chemical and structural stability. This research offers a novel strategy for regulating the Cr(VI) reduction by establishing core-shell photocatalytic materials.

Ultrasonic controllable synthesis of sulfur-functionalized metal-organic frameworks (S-MOFs) and their application in piezo-photocatalytic rapid reduction of hexavalent chromium (Cr)

The United Nations' Sustainable Development Goals (SDGs) are significant in guiding modern scientific research. In recent years, scholars have paid much attention to MOFs materials as green materials. However, piezo catalysis of MOFs materials has not been widely studied. Piezoelectric materials can convert mechanical energy into electrical energy, while MOFs are effective photocatalysts for removing pollutants. Therefore, it is crucial to design MOFs with piezoelectric properties and photosensitivity. In this study, sulfur-functionalized metal-organic frameworks (S-MOFs) were prepared using organic sulfur-functionalized ligand (H2TDC) ultrasonic synthesis to enhance their piezoelectric properties and visible light absorption. The study demonstrated that the S-MOFs significantly enhanced the reduction of a 10 mg/L solution of hexavalent chromium to 99.4 % within 10 min, using only 15 mg of catalyst. The orbital energy level differences of the elements were analyzed using piezo response force microscopy (PFM) and X-ray photoelectron spectroscopy (XPS). The results showed that MOFs functionalized with sulfur atom ligands have a built-in electric field that facilitates charge separation and migration. This study presents a new approach to enhance the piezoelectric properties of MOFs, which broadens their potential applications in piezo catalysis and piezo-photocatalysis. Additionally, it provides a sustainable method for reducing hexavalent chromium, contributing to the achievement of sustainable development goals, specifically SDG-6, SDG-7, SDG-9, and SDG-12.

Highly Efficient Photocatalytic Degradation of Imidacloprid Based on Iron Metal-Organic Frameworks of Mesoporous NH2-MIL-88b/Graphite Carbon Nitride Nanocomposites by Visible Light Driven in Aqueous Media

Pesticides that protect crops from insects and other pests are some of the main causes of water pollution. Imidacloprid (IMC) is the most widely used insecticide in the world and should be removed from the environment. This work aims to prepare mesoporous nanocomposites to increase the photodegradation efficiency of IMC. To improve the surface properties and enhance the photocatalytic activity, mesoporous nanocomposites with different weight ratios of graphite carbon nitride (CN = 125, 250, and 500 mg) were prepared by the solvothermal method. Mesoporous NH2-MIL-88b(Fe)/graphite carbon nitride (CN = 250 mg, NH2-MCN-2) nanocomposites showed the best photocatalytic performance. To save the time and cost of the experiments, central composite design (CCD) and response surface methodology (RSM) were used and the results were obtained as the initial concentration of IMC (20 mg L-1), amount of photocatalyst (0.76 g L-1), pH = 5, and degradation time ∼46 min. The maximum photocatalytic degradation efficiency estimated by the model was obtained at 96.31%, which is very close to the actual value of 95.47%. The mesoporous NH2-MCN-2 nanocomposite showed excellent stability and suitable reusability with a maximum degradation of 84.5% after five cycles. Results obtained from kinetic studies indicated a rate constant value of 0.08 min-1, and isotherm models showed that equilibrium data are more consistent with the Langmuir model in photocatalytic degradation. Electrochemical experiments showed significant improvement in the electron transfer rate and photocatalytic activity of the mesoporous NH2-MCN-2 nanocomposite. Different trapping agents were used to investigate the effective active species in IMC photodegradation, and it was determined that the hole (h+) and OH radical (•OH) play the main role. The possible mechanism for IMC photocatalytic degradation was suggested by Mott-Schottky (M-S) electrochemical impedance.

Tungsten-based nanocatalysts with different structures for visible light responsive photocatalytic degradation of bisphenol A

Environmental pollution, such as water contamination, is a critical issue that must be absolutely addressed. Here, three different morphologies of tungsten-based photocatalysts (WO3 nanorods, WO3/WS2 nanobricks, WO3/WS2 nanorods) are made using a simple hydrothermal method by changing the solvents (H2O, DMF, aqueous HCl solution). The as-prepared nanocatalysts have excellent thermal stability, large porosity, and high hydrophilicity. The results show all materials have good photocatalytic activity in aqueous media, with WO3/WS2 nanorods (NRs) having the best activity in the photodegradation of bisphenol A (BPA) under visible-light irradiation. This may originate from increased migration of charge carriers and effective prevention of electron‒hole recombination in WO3/WS2 NRs, whereby this photocatalyst is able to generate more reactive •OH and •O2- species, leading to greater photocatalytic activity. About 99.6% of BPA is photodegraded within 60 min when using 1.5 g/L WO3/WS2 NRs and 5.0 mg/L BPA at pH 7.0. Additionally, the optimal conditions (pH, catalyst dosage, initial BPA concentration) for WO3/WS2 NRs are also elaborately investigated. These rod-like heterostructures are expressed as potential catalysts with excellent photostability, efficient reusability, and highly active effectivity in different types of water. In particular, the removal efficiency of BPA by WO3/WS2 NRs reduces by only 1.5% after five recycling runs and even reaches 89.1% in contaminated lake water. This study provides promising insights for the nearly complete removal of BPA from wastewater or different water resources, which is advantageous to various applications in environmental remediation.

Preparation of core-shell structure Ag@TiO2 plasma photocatalysts and reduction of Cr(VI): Size dependent and LSPR effect

The poor light absorption and low carrier separation efficiency of Titanium dioxide (TiO2) limit its further application. The introduction of plasma metal Ag have the potential to solve these drawbacks owing to its plasma resonance effect. Thus core-shell structure Ag@TiO2 plasma photocatalysts was prepared by using facile reduction method in this work. More specifically, Ag@TiO2 composite catalysts with different Ag loading amounts were prepared in the presence of surfactant PVP. Ag@TiO2 demonstrates excellent light absorption performance and photoelectric separation efficiency compared with pure TiO2. As a result, it displays excellent performance of Cr(VI) reduction under visible light. The optimal composite catalysts Ag@TiO2-5P achieves exceptional visible-light-driven photocatalytic Cr(VI) reduction efficiency of 0.01416 min-1 that is 2.29 times greater than pure TiO2. To investigate the role of PVP, we also synthesized Ag@TiO2-5 without PVP. The experimental results show that although Ag@TiO2-5 Cr(VI) reduction performance is superior to pure TiO2, it significantly decreases compared with Ag@TiO2-5P. The results of TEM and optoelectronic testing show that agglomeration of Ag particles leads to a decrease in the photoelectric separation efficiency of Ag@TiO2-5. The smaller Ag particles provide more active sites and demonstrating a stronger overall local surface plasmon resonance (LSPR) effect. DMPO spin-trapping ESR spectra testing indicates that ∙O2- and ∙OH are the main reactive species. This research provides a potential strategy to prepare Ag-based plasma photocatalysts for environment protection.

Simple and rapid determination of tartrazine in fake saffron using the metal organic framework (Fe SA MOF@CNF) by HPLC/PDA

The present study of a novel metal-organic framework containing Fe single atoms doped on electrospun carbon nanofibers (Fe SA-MOF@CNF) based on dispersive micro solid phase extraction (D-μ-SPE) using HPLC-PDA for detection tartrazine in fake saffron samples was designed. The Fe SA-MOF@CNF sorbent was extensively characterized through various techniques including N2 adsorption-desorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The specific area of surface of the sorbent was 577.384 m2/g. The study variables were optimized via the central composite design (CCD), which included a sorbent mass of 15 mg, a contact time of 6 min, a pH of 7.56, and a tartrazine concentration of 300 ng/ml. Under the optimum condition, the calibration curve of this method was linear in the range of 5-1000 ng/mL, with a correlation coefficient of 0.992. The LOD and LOQ values were ranged 0.38-0.74 and 1.34-2.42 ng/ml, respectively. This approach revealed significant improvements, including high extraction recovery (98.64), recovery rates (98.43-102.72%), and accuracy (RSDs < 0.75 to 3.6%). the enrichment factors were obtained in the range of 80.6-86.4 with preconcentration factor of 22.3. Consequently, the D-μ-SPE method based on synthesized Fe SA-MOF@CNF could be recommended as a sustainable sorbent for detecting tartrazine in saffron samples.

Design of novel solar-light-induced KBi6O9I/Ag-AgVO3 nanophotocatalyst with Ag-bridged Z-scheme charge carriers separation and boosted photo-elimination of hospital effluents

In this research, a novel solar-light-induced KBi6O9I/Ag-AgVO3 nanophotocatalyst with an Ag-bridged Z-scheme structure has been designed and synthesized through a sonochemical method to photo-degrade antibiotic hospital contaminants under simulated solar-light irradiation. Synthesized nanophotocatalysts with varying KBi6O9I to Ag-AgVO3 weight ratios underwent N2 Adsorption-Desorption, XRD, TEM, UV-Vis DRS, FESEM and PL analyses. The Ag-bridged Z-scheme-structured KBi6O9I/Ag-AgVO3 (1:1) nanophotocatalyst, demonstrated broad light absorption within the solar-light spectrum and showcased effective photocatalytic efficacy in degrading tetracycline antibiotic (88.3% and 83.5% removal for 25 and 50 mg/L, respectively, after 120 min). This performance outperformed other composited photocatalysts, as well as pure Ag-AgVO3 and KBi6O9I photocatalysts. The enhanced degradation efficiency of the KBi6O9I/Ag-AgVO3 (1:1) composite can be ascribed to the synergistic interaction of various elements. These include the surface plasmon resonance impact of silver nanoparticles, their pronounced sensitivity to solar irradiation, and the Z-scheme heterojunction configuration. Collectively, these factors work together to minimize the recombination rate of photoinduced electron-hole pairs, thereby amplifying the efficacy of photodegradation. Furthermore, the KBi6O9I/Ag-AgVO3 (1:1) composite photocatalyst displayed sustained pollutants elimination performance even after undergoing four consecutive cycles.

Fe-Co-Based Metal-Organic Frameworks as Peroxidase Mimics for Sensitive Colorimetric Detection and Efficient Degradation of Aflatoxin B1

Building multifunctional platforms for integrating the detection and control of hazards has great significance in food safety and environment protection. Herein, bimetallic Fe-Co-based metal-organic frameworks (Fe-Co-MOFs) peroxidase mimics are prepared and applied to develop a bifunctional platform for the synergetic sensitive detection and controllable degradation of aflatoxin B1 (AFB1). On the one hand, Fe-Co-MOFs with excellent peroxidase-like activity are combined with target-induced catalyzed hairpin assembly (CHA) to construct a colorimetric aptasensor for the detection of AFB1. Specifically, the binding of aptamer with AFB1 releases the prelocked Trigger to initiate the CHA cycle between hairpin H2-modified Fe-Co-MOFs and hairpin H1-tethered magnetic nanoparticles to form complexes. After magnetic separation, the colorimetric signal of the supernatant in the presence of TMB and H2O2 is inversely proportional to the target contents. Under optimal conditions, this biosensor enables the analysis of AFB1 with a limit of detection of 6.44 pg/mL, and high selectivity and satisfactory recovery in real samples are obtained. On the other hand, Fe-Co-MOFs with remarkable Fenton-like catalytic degradation performance for organic contaminants are further used for the detoxification of AFB1 after colorimetric detection. The AFB1 is almost completely removed within 120 min. Overall, the introduction of CHA improves the sensing sensitivity; efficient postcolorimetric-detection degradation of AFB1 reduces the secondary contamination and risk to the experimental environment and operators. This strategy is expected to provide ideas for designing other multifunctional platforms to integrate the detection and degradation of various hazards.

Leveraging the photocatalytic Cr (VI) reduction by an IRMOF-3@NH2-MIL-101 (Fe) heterostructure based on interfacial Lewis acid-base interaction

A strategy to enhance the photocatalytic performance of metal-organic framework (MOF) based systems for the efficient elimination of Cr(VI) ions from polluted water under visible light irradiation has been developed by constructing MOF@MOF heterojunctions. Specifically, IRMOF-3 was grown in situ around NH2-MIL-101(Fe) based on interfacial Lewis acid-base interaction using 2-aminoterephthalic acid (ATA) as a linker, resulting in the formation of a MOF@MOF heterojunction, designated as IRMOF-3@NH2-MIL-101(Fe). In comparison to individual MOFs, the IRMOF-3@NH2-MIL-101(Fe) heterojunction exhibited a significantly higher photocatalytic reduction efficiency for Cr(VI), achieving a reduction of 95.98% within 120 min under visible-light irradiation. This performance surpasses that of individual MOFs and most reported photocatalysts. Additionally, the mechanism underlying Cr(VI) reduction by IRMOF-3@NH2-MIL-101(Fe) was comprehensively elucidated by analyzing optoelectronic properties, energy band structure, and structural results. It is worth noting that this study represents the first documented instance of photocatalytic Cr(VI) reduction utilizing IRMOF-3 and its interaction with NH2-MIL-101(Fe). The MOF@MOF photocatalyst, leveraging the synergistic effects of its various components, holds great promise for efficiently removing harmful pollutants from water and finds significant potential applications in environmental remediation.

Advancements in TiO2-based photocatalysis for environmental remediation: Strategies for enhancing visible-light-driven activity

Researchers have focused on efficient techniques for degrading hazardous organic pollutants due to their negative impacts on ecological systems, necessitating immediate remediation. Specifically, TiO2-based photocatalysts, a wide-bandgap semiconductor material, have been extensively studied for their application in environmental remediation. However, the extensive band gap energy and speedy reattachment of electron (e-) and hole (h+) pairs in bare TiO2 are considered major disadvantages for photocatalysis. This review extensively focuses on the combination of semiconducting photocatalysts for commercial outcomes to develop efficient heterojunctions with high photocatalytic activity by minimizing the e-/h+ recombination rate. The improved activity of these heterojunctions is due to their greater surface area, rich active sites, narrow band gap, and high light-harvesting tendency. In this context, strategies for increasing visible light activity, including doping with metals and non-metals, surface modifications, morphology control, composite formation, heterojunction formation, bandgap engineering, surface plasmon resonance, and optimizing reaction conditions are discussed. Furthermore, this review critically assesses the latest developments in TiO2 photocatalysts for the efficient decomposition of various organic contaminants from wastewater, such as pharmaceutical waste, dyes, pesticides, aromatic hydrocarbons, and halo compounds. This review implies that doping is an effective, economical, and simple process for TiO2 nanostructures and that a heterogeneous photocatalytic mechanism is an eco-friendly substitute for the removal of various pollutants. This review provides valuable insights for researchers involved in the development of efficient photocatalysts for environmental remediation.

Duple charge separation and plasmonically enriched DSSC and piezo-photocatalytic efficacy of Au anchored perovskite Gd3+:BiFeO3 nanospheres

Enhancing the solar-physical conversion efficacy ability of the nanomaterials is an essential for real-time implementation. We report the enhanced solar-physical efficiency of the BiFeO3 nanospheres via Gd3+ doping and Au nanoparticles decoration. Initially, we have obtained the Bi1-xGdxFeO3 nanospheres were attained via a simple solvothermal technique and then citrate reduction of Au was conducted. Obtained perovskite BiFeO systems were studied for the Gd3+ doping, crystalline phase and elemental purity using the XRD and XPS techniques. Transmission electron microscope had revealed the ∼400 nm sized BiFeO3 nanospheres. Optical absorption spectrum revealed the enhanced visible photon absorption occurring in BiFeO3 for both Gd3+ doping and Au decoration. The bandgap values of pristine, 1%, 3% and 5% Gd3+ doped in BiFeO3 are 2.2 eV, 2.19 eV, 2.17 eV and 2.12 eV, respectively. Conducted photoluminescence revealed the dual electron trapping occurring in BiFeO3 via Gd3+ ions and Au nanoparticles. LED light assisted 72% of piezo-photocatalytic degradation efficiency of Tetracycline is achieved with Bi0 95Fe0 05O3/Au, whereas the photo catalytic is only 65% and piezo catalytic efficiency is 58%. In recyclable studies the Bi0.95Gd0.05FeO3/Au had shown the consistent piezo-photocatalytic efficiency for 3 reaction cycles. Further, fabricated DSSC studies revealed that near 30 % enhanced solar photovoltaic efficiency for Bi0 95Fe0 05O3/Au (η = 6.5%) solar cells on par to the pristine BiFeO3 (η = 5.02%).

Visible Light-Assisted Degradation of Sulfamethoxazole on 2D/0D Sulfur-Doped Bi2O3/MnO2 Z-Scheme Heterojunction Immobilized Photocatalysts

Retrieving the spent photocatalysts from the reaction system is always a challenging task. Therefore, the present work is focused on immobilizing sulfur-doped-Bi2O3/MnO2 (S-BOMO) heterojunction photocatalysts over different support matrices and evaluating their performance for the removal of sulfamethoxazole (SMX) in water under visible light. Our findings revealed S-BOMO coated clay beads (S-BOMO CCB) achieving more than 86% (240 min) SMX degradation ∼3, ∼1.3, and ∼2 times higher compared to S-BOMO coated on the different substrates, including glass beads, floating stones, and polymer material substrates, respectively. Mott-Schottky measurements confirmed the construction of the Z-scheme heterojunction involving MnO2 and 2S-Bi2O3. This Z-scheme mechanism, along with its narrow band gap of 1.58 eV, resulted in a rapid spatial transfer of the photogenerated charge carriers between the semiconductors and is believed to enhance the overall photocatalytic activity of the nanocomposite. Radical trapping and electron paramagnetic resonance results clearly established the active role of hydroxyl radicals and hydrogen peroxide in the degradation of SMX. Further, the 2S-BOMO CCB demonstrated excellent stability and photocatalytic activity over multiple runs. According to the sensitivity analysis and the results of anion effect experiments, phosphate and sulfate ions exhibit a significant impact on sulfamethoxazole degradation. Toxicity analysis revealed that 2S-BOMO CCB and sulfamethoxazole degradation byproducts were apparently innocuous. Additionally, the practical applicability of 2S-BOMO CCB was examined in various real water matrices, with the degradation efficiency followed the order: tap water < groundwater < surface water < hospital wastewater < municipal wastewater < pharmaceutical industry wastewater. The economic assessment revealed the reduction in the overall cost of the immobilized 2S-BOMO following the recovery process. Overall, the findings of this work provided critical insights into the synthesis and performance of incredibly effective and stable immobilized photocatalysts for the degradation of pharmaceutical pollutants.

Reasonable decoration of CuO/Cd0.5Zn0.5S nanoparticles onto flower-like Bi5O7I as boosted step-scheme photocatalyst for reinforced photodecomposition of bisphenol A and Cr(VI) reduction in wastewater

Building S-scheme heterostructures is a sophisticated approach to receiving outstanding catalysts for environmental detoxification. Herein, ternary CuO/Cd0.5Zn0.5S/Bi5O7I (CO/CZS/BOI) nanocomposites were constructed by in-situ decorating of CuO and Cd0.5Zn0.5S nanoparticles onto Bi5O7I micro-sphere in a facile route. The optimal CO/CZS/BOI reflected reinforced bisphenol A (BPA) photo-oxidation (95% in 70 min) and Cr(VI) photo-reduction (96.6 in 60 min) under visible light. Besides, CO/CZS/BOI afforded 5.10 (4.44), 4.42 (3.71), and 6.60 (5.27) fold reinforcement in the BPA (Cr(VI)) photo-reaction rate compared to BOI, CZS, and CO, respectively. This behavior was linked to the development of S-scheme mechanisms resulting from the co-effects of BOI, CZS, and CO in retaining the optimum redox capacity, facilitating the dissolution of photo-carriers, increasing reactive sites, and strengthening the visible-light response. The parameters influencing the catalytic reaction of CO/CZS/BOI, such as light intensity, catalyst dosage, and pH, were deeply studied. The quenching tests declared the prominent roles •O2- and •OH in the breaking down of BPA and the participation of electrons and •O2- in the photocatalytic conversion of Cr(VI). The cyclic tests verified the robust photostability of CO/CZS/BOI, which is associated with the reintegration process between the free h+ coming from CZS and the photo-induced e- of CO and BOI in the S-scheme system. In conclusion, the present study provides a profound understanding of the photo-reaction mechanism of CO/CZS/BOI and introduces a novel concept for constructing a superior dual-Scheme system for efficient wastewater detoxification.

S-scheme MOF-on-MOF heterojunctions for enhanced photo-Fenton Cr(VI) reduction and antibacterial effects

The photocatalytic efficiency is commonly restrained by inferior charge separation rate. Herein, the S-scheme MIL-100(Fe)/NH2-MIL-125(Ti) (MN) photo-Fenton catalyst with the built-in electric field (BEF) was successfully constructed by a simple ball-milling technique. As a result, the MN-3 (the mass ratio of MIL-100(Fe) to NH2-MIL-125(Ti) was 3) composite presented the best visible-light-induced photocatalytic ability, in contrast to pure MIL-100(Fe) and NH2-MIL-125(Ti). The reduction efficiency of Cr(VI) almost reached 100% within 35 min of illumination. Moreover, the MN-3 heterojunction also exhibited the highest antibacterial activity, and about 100% E. coli and more than 90% S. aureus were killed within 60 min of illumination. In photo-Fenton system, In the photo-Fenton system, e-, O2•- and Fe2+ played vital roles for Cr(VI) reduction, and •OH, h+ and O2•- and 1O2 were responsible for sterilization. Additionally, 5 cyclic tests and relevant characterizations confirmed the excellent repeatability and stability of the composite. Also, the S-scheme charge transfer process was put forward. This work offers a novel idea for establishing the MOF-on-MOF photo-Fenton catalyst for high-efficiency environmental mitigation.

Synergistic doping with Ag, CdO, and ZnO to overcome electron-hole recombination in TiO2 photocatalysis for effective water photo splitting reaction

This manuscript is dedicated to a comprehensive exploration of the multifaceted challenge of fast electron-hole recombination in titanium dioxide photocatalysis, with a primary focus on its critical role in advancing the field of water photo splitting. To address this challenge, three prominent approaches-Schottky barriers, Z-scheme systems, and type II heterojunctions-were rigorously investigated for their potential to ameliorate TiO2's photocatalytic performance toward water photo splitting. Three distinct dopants-silver, cadmium oxide, and zinc oxide-were strategically employed. This research also delved into the dynamic interplay between these dopants, analyzing the synergetic effects that arise from binary and tertiary doping configurations. The results concluded that incorporation of Ag, CdO, and ZnO dopants effectively countered the fast electron-hole recombination problem in TiO2 NPs. Ag emerged as a critical contributor at higher temperatures, significantly enhancing photocatalytic performance. The photocatalytic system exhibited a departure from Arrhenius behavior, with an optimal temperature of 40°C. Binary doping systems, particularly those combining CdO and ZnO, demonstrated exceptional photocatalytic activity at lower temperatures. However, the ternary doping configuration involving Ag, CdO, and ZnO proved to be the most promising, surpassing many functional materials. In sum, this study offers valuable insights into how Schottky barriers, Z-scheme systems, and type II heterojunctions, in conjunction with specific dopants, can overcome the electron-hole recombination challenge in TiO2-based photocatalysis. The results underscore the potential of the proposed ternary doping system to revolutionize photocatalytic water splitting for efficient green hydrogen production, significantly advancing the field's understanding and potential for sustainable energy applications.

Accelerated electron and mass transfer through constructing H2WO4/Ti3C2/g-C3N4 Z-scheme photocatalyst for environmental remediation

The catalytic efficiency of photocatalysts highly depends on electron transport and mass transfer. Herein, we designed and prepared an effective H2WO4/Ti3C2/g-C3N4 (HTC) Z-scheme heterojunction through interfacial engineering strategy. The results manifested that 97.4% of Cr(VI) (80 μM, 50 mL) could be removed by HTC heterojunction within 10 min under visible light irradiation. The reduction rate constant of Cr(VI) for H2WO4/g-C3N4 (HC) heterojunction increased by a factor of 21 after introducing the conductive Ti3C2. Moreover, 96% of tetracycline (TC, 10 mg L-1, 50 mL) could be degraded by HTC heterojunction within 30 min. The electronic conductivity and ionic diffusion coefficient of HC heterojunction increased by a factor of 64 and 1064 after adding Ti3C2, respectively. This result indicated that the introduction of highly conductive Ti3C2 significantly improved the electron and mass transfer of the heterojunction. Meanwhile, the HCT heterojunction displayed favorable photocurrent, and keep excellent photostability during the long-term test. Moreover, density functional theory (DFT) calculations demonstrated that the internal electric field (IEF) from g-C3N4 to H2WO4 in HCT heterojunction promotes the combination of the photoinduced electrons in the H2WO4 conduction band (CB) with photoinduced holes in the g-C3N4 valence band (VB), thus accelerating the charge transfer in the HCT Z-scheme heterojunction. The antibacterial efficiency of HTC heterojunction against E. coli and S. aureus could reach up to 98.4% and 99.7%, respectively. The degradation intermediates and the potential degradation mechanism of TC were analyzed and proposed based on the results of HPLC-MS analysis. Moreover, the toxicity of TC and degradation intermediates were estimated by Toxicity Estimation Software (T.E.S.T.) based on quantitative structure-activity relationship (QSAR). This work provided a valuable guideline for designing the effective MXene-based Z-scheme heterojunction for environmental remediation.

Ferric-ellagate complex: A promising multifunctional photocatalyst

The semiconductors have exhibited great potential in the field of photocatalytic energy production, environmental remediation and bactericidal. Nevertheless, those inorganic semiconductors are still restricted in commercial application due to the drawbacks of easy agglomeration and low solar energy conversion efficiency. Herein, ellagic acid (EA) based metal-organic complexes (MOCs) were synthesized through a facile stirring process at room temperature with Fe³⁺, Bi³⁺ and Ce³⁺ as the metal center. The EA-Fe photocatalyst exhibited superior photocatalytic activity toward Cr(VI) reduction, where Cr(VI) were completely removed within 20 min. Meanwhile, EA-Fe also displayed good photocatalytic degradation of organic contaminants and photocatalytic bactericidal performance. The photodegradation rates of TC and RhB by EA-Fe were 15 and 5 times that by bare EA, respectively. Moreover, EA-Fe was capable of effectively eliminating both E. coli and S. aureus bacteria. It was found that EA-Fe was capable of generating superoxide radicals, which could participate in the reduction of heavy metals, degradation of organic contaminants and inactivation of bacteria. A photocatalysis-self-Fenton system could be established by EA-Fe solely. This work would provide a new insight for designing multifunctional MOCs with high photocatalytic efficiency.

Synergistic effect of double Schottky potential well and oxygen vacancy for enhanced plasmonic photocatalytic U(VI) reduction

Plasmonic photocatalysis is an effective strategy to solve radioactive uranium hazards in wastewater. A plasmonic photocatalyst Bi/Bi₂O_3-x@COFs was synthesized by in-situ growth of covalent organic frameworks (COFs) on Bi/Bi₂O_3-x surface for the U(VI) adsorption and plasmonic photoreduction in rare earth tailings wastewater. The presence of oxygen vacancy in Bi/Bi₂O_3-x and Schottky potential well formed by Bi and Bi₂O_3-x interface increased the number of free electrons, which induced localized surface plasmon resonance (LSPR) and enhanced the light absorption performance of composites. In addition, oxygen vacancy improved the Fermi level of Bi/Bi₂O_3-x, leading to another potential well between Bi₂O_3-x and COFs interface. The electron transport direction was reversed, thus increasing the electron density of COFs layer. COFs was an N-type semiconductor with specific binding U(VI) groups and suitable band structure, which could be used as an active reaction site. Bi/Bi₂O_3-x@COFs had 1411.5 mg g^-1 removal capacity and high separation coefficient for U(VI) due to the synergistic action of photogenerated electrons and hot electrons. Moreover, the removal rate of uranium from rare earth tailings wastewater by regenerated Bi/Bi₂O_3-x@COFs was over 93.9%. The scheme of introducing LSPR and Schottky potential well provides another way to improve the photocatalytic effect.