Bismuth-based Metal-organic Framework Research Articles

Facile Synthesis of a Layered Bismuth-Based MOF With Superhydrophobic-Oleophilic Property and High Oil-Water Separation Performance.

Metal organic frameworks (MOFs) are a class of potential superhydrophobic-oleophilic materials. The organic ligands in superhydrophobic MOFs usually contain long alkyl chains, fluorine groups or aromatic rings with large π conjugation, the preparation of which suffers from high cost, complex operation and so on. In addition, the topological structure of MOFs plays an important role in the hydrophobicity, which may be ignored previously. Here we report a superhydrophobic-oleophilic MOF (BiPPA2) obtained by a facile and fast method, which not only displays a large water contact angle of up to 163° and a small sliding angle of nearly equal to 0°, but also exhibits high sorption capacity for multiple oils and organic solvents, well reusability and high oil retention. In addition, BiPPA2 is stable in a wide pH range (0.5-11.0). Finally, the single crystal structure of BiPPA2 is resolved to reveal the intrinsic reason for the super-hydrophobicity. This work may inspire the further design of pristine superhydrophobic MOFs based on a simple method, which enriches the family of superhydrophobic MOFs and has great significance for practical applications.

Bismuth‐based metal‐organic frameworks and derivatives for photocatalytic applications in energy and environment: Advances and challenges

AbstractPhotocatalysis is an environmentally friendly technology for the utilizations of solar energy and has garnered significant attention in both scientific and industrial sectors. Developing cost‐effective semiconductive materials is the core issue in photocatalysis. Bismuth‐based metal‐organic frameworks (Bi‐MOFs) have emerged as attractive candidates in various photocatalytic applications, and Bi‐MOFs derivatives further expand and consolidate their promising potential in the realm of photocatalysis. Various modification strategies including in‐situ tailoring or external doping, as well as meticulous design and selection of metal nodes and organic linkers allow for fine control over the surface multifunctionality in Bi‐MOF‐based and derived photocatalytic composites with adjustable energy band structures and enhanced photocatalytic performance. In this review, the recent progress in the synthesis of diverse Bi‐MOFs‐based materials, Bi‐MOFs derivatives, and their Bi‐containing semiconductive composites were systemically analyzed and reviewed. The state‐of‐the‐art research progresses in the applications of Bi‐MOFs and derivatives, as well as composites in photocatalytic water splitting for hydrogen production, photodegradation of organic pollutants, and photocatalytic carbon dioxide reduction are comprehensively summarized. The relationships between structures, properties, and photocatalytic performance of Bi‐based semiconductive composites are discussed in detail. In addition, the perspectives and future challenges on Bi‐MOFs‐based and derived materials for photocatalytic applications are also offered.

Novel MOF-derived dual Z-scheme g-C3N4/Bi2O2CO3/β-Bi2O3 heterojunctions with enhanced photodegradation of tetracycline hydrochloride

A series of novel g-C3N4/Bi2O2CO3/β-Bi2O3 ternary heterojunctions were synthesized by bismuth-based metal-organic framework (Bi-MOF) derived strategy. The developed ternary composites represented higher specific surface area, superior utilization of visible light, boosted charge transfer and spatial separation capabilities through the electron transfer channels by Bi-N bonds and the construction of heterojunctions. Under visible light irradiation, the optimal composites exhibited excellent photocatalytic performance, which could degrade around 96.7 % of tetracycline hydrochloride (TCH) within 120 min. Furthermore, the possible charge carrier transport mechanism of dual Z-scheme heterojunctions was revealed. Besides, improved composites presented preeminent photodegradation ability over a wide pH scope, intense anti-interference to manifold anions, and excellent adaptability for various pollutants and even diverse water quality. Meanwhile, the growth of Escherichia coli (E. coli) as toxicity test validated low toxicity of the intermediates. Overall, the novel photocatalysts might inspire the rational design of ternary heterojunctions and offer a green way for efficient degradation of organic pollutants.

A novel antibacterial immune activator: Bi-MOF acts as H2S scavenger to suppress HIF-1α S-sulfhydration and alleviate implant-associated infection

Implant-associated infection (IAI) has significantly impeded the progress of surgery, and a properly functioning antibacterial immune response is critical for preventing persistent infection and reinfection. However, the efficacy of current infection immunotherapy remains considerably suboptimal, primarily because of the lack of validated therapeutic targets and interventions. Herein, we identify a bismuth-based metal organic frameworks (Bi-MOF) as an efficient intracellular hydrogen sulfide (H2S) scavenger that promotes the antibacterial response of macrophages through the inhibition of hypoxia inducible factor-1α (HIF-1α) S-sulfhydration and subsequent ubiquitin-dependent degradation. The reduction in H2S levels by Bi-MOF in vivo contributes to accelerated the clearance of bacteria, prevention of bone destruction, and augmentation of innate immunity in a mouse IAI model. Moreover, Bi-MOF also boost bacteria-specific adaptive immunity, thereby generating long-lasting protection against reinfection. Together, our results demonstrate that H2S-responsive Bi-MOF offer a promising immunotherapeutic approach as a potential alternative to antibiotics for managing stubborn IAIs.

Engineering Porosity and Functionality in a Robust Twofold Interpenetrated Bismuth-Based MOF: Toward a Porous, Stable, and Photoactive Material.

Defect engineering in metal-organic frameworks (MOFs) has gained worldwide research traction, as it offers tools to tune the properties of MOFs. Herein, we report a novel 2-fold interpenetrated Bi-based MOF made of a tritopic flexible organic linker, followed by missing-linker defect engineering. This procedure creates a gradually augmented micro- and mesoporosity in the parent (originally nonporous) network. The resulting MOFs can tolerate a remarkable extent of linker vacancy (with absence of up to 60% of linkers per Bi node) created by altering the crystal-growth rate as a function of synthesis temperature and duration. Owing to the enhanced porosity and availability of the uncoordinated Lewis acidic Bi sites, the defect-engineered MOFs manifested improved surface areas, augmented CO2 and water vapor uptake, and catalytic activity. Parallel to this, the impact of defect engineering on the optoelectronic properties of these MOFs has also been studied, offering avenues for new applications.

Construction of BiOCl/bismuth-based halide perovskite heterojunctions derived from the metal-organic framework CAU-17 for effective photocatalytic degradation

The designed synthesis of an S-scheme heterojunction has possessed a great potential for improving photocatalytic wastewater treatment by demonstrating increased the photoredox capacity and improved the charge separation efficiency. Here, we introduce the fabrication of a heterojunction-based photocatalyst comprising bismuth oxychloride (BiOCl) and bismuth-based halide perovskite (BHP) nanosheets, derived from metal-organic frameworks (MOFs). Our composite photocatalyst is synthesized through a one-pot solvothermal strategy, where a halogenation process is applied to a bismuth-based metal-organic framework (CAU-17) as the precursor for bismuth sourcing. As a result, the rod-like structure of CAU-17 transforms into well-defined plate and nanosheet architectures after 4 and 8 h of solvothermal treatment, respectively. The modulation of the solvothermal reaction time facilitates the establishment of an S-scheme heterojunction, resulting in an increase in the photocatalytic degradation efficiency of rhodamine B (RhB) and sulfamethoxazole (SMX). The optimized BiOCl/BHP composite exhibits superior RhB and SMX degradation rates, achieving 99.8% degradation of RhB in 60 min and 75.1% degradation of SMX in 300 min. Also, the optimized BiOCl/BHP composite (CAU-17-st-8h sample) exhibited the highest rate constant (k = 3.48 × 10−3 min−1), nearly 6 times higher than that of the bare BHP in the photocatalytic degradation process of SMX. The enhanced photocatalytic efficiency can be endorsed to various factors: (i) the in-situ formation of two-components BiOCl/BHP photocatalyst, derived from CAU-17, effectively suppresses the aggregation of pristine BHP and BiOCl particles; (ii) the S-scheme heterostructure establishes a closely-knit interfacial connection, thereby facilitating efficient pathways for charge separation/transfer; and (iii) the BiOCl/BHP heterostructure enhances its capacity to absorb visible light. Our investigation establishes an effective strategy for constructing heterostructured photocatalysts, offering significant potential for application in photocatalytic wastewater treatment.

Design and Synthesis of Bismuth-based Metal-Organic Frameworks for Photothermal Energy Conversion

Design and Synthesis of Bismuth-based Metal-Organic Frameworks for Photothermal Energy Conversion

Strong Second-Harmonic Generation Induced by a Triphenylamine-Based Bismuth-Organic Framework for Photocatalytic Activity Enhancement.

Taking advantage of the well-defined geometry of metal centers and highly directional metal-ligand coordination bonds, metal-organic frameworks (MOFs) have emerged as promising candidates for nonlinear optical (NLO) materials. In this work, taking a photoresponsive carboxylate triphenylamine derivative as an organic ligand, a bismuth-based MOF, Bi-NBC, NBC = 4',4‴,4‴″-nitrilotris(([1,1'-biphenyl]-4-carboxylic acid)) is obtained. Structure determination reveals that it is a potential NLO material derived from its noncentrosymmetric structure, which is finally confirmed by its rarely strong second harmonic generation (SHG) effect. Theoretical calculations reveal that the potential difference around Bi atoms is large; therefore, it leads to a strong local built-in electric field, which greatly facilitates the charge separation and transfer and finally improves the photocatalytic performance. Our results provide a reference for the exploration of MOFs with NLO properties.

Regulating concentration of surface oxygen vacancies in Bi2MoO6/Bi-MOF for boosting photocatalytic ammonia synthesis

Surface oxygen vacancies (OVs) engineering has been widely adopted as an effective strategy to enhance photocatalytic performance. At present, photocatalytic systems capable of precisely regulating surface OVs concentrations, which could help illuminate the effects of the surface OVs concentration on N2 fixation activity, are still scarce. Herein, bismuth-based metal organic framework (Bi-MOF) was loaded onto the surface of Bi2MoO6 (BMO) as an operable platform, and the OVs concentration in the Bi-MOF component of BMO/Bi-MOF could be regulated by reduction of bismuth ions therein. Experimental results confirm that optimum construction of OVs in the Bi-MOF promotes the photoelectrons transfer from BMO to Bi-MOF, facilitating the activation of N2 at OVs. Consequently, the optimized catalyst shows superior performance in NH3 production, which reaches 125.78 μmol h−1 g−1, 21.4 higher than that of BMO. This work underline the significance of regulating surface OVs concentration, providing inspiration for the development of efficient OVs-modified photocatalysts.

SU-101 for the removal of pharmaceutical active compounds by the combination of adsorption/photocatalytic processes

Pharmaceutical active compounds (PhACs) are some of the most recalcitrant water pollutants causing undesired environmental and human effects. In absence of adapted decontamination technologies, there is an urgent need to develop efficient and sustainable alternatives for water remediation. Metal–organic frameworks (MOFs) have recently emerged as promising candidates for adsorbing contaminants as well as providing photoactive sites, as they possess exceptional porosity and chemical versatility. To date, the reported studies using MOFs in water remediation have been mainly focused on the removal of a single type of PhACs and rarely on the combined elimination of PhACs mixtures. Herein, the eco-friendly bismuth-based MOF, SU-101, has been originally proposed as an efficient adsorbent-photocatalyst for the elimination of a mixture of three challenging persistent PhACs, frequently detected in wastewater and surface water in ng L−1 to mg·L−1 concentrations: the antibiotic sulfamethazine (SMT), the anti-inflammatory diclofenac (DCF), and the antihypertensive atenolol (At). Adsorption experiments of the mixture revealed that SU-101 exhibited a great adsorption capacity towards At, resulting in an almost complete removal (94.1 ± 0.8% for combined adsorption) in only 5 h. Also, SU-101 demonstrated a remarkable photocatalytic activity under visible light to simultaneously degrade DCF and SMT (99.6 ± 0.4% and 89.2 ± 1.4%, respectively). In addition, MOF-contaminant interactions, the photocatalytic mechanism and degradation pathways were investigated, also assessing the toxicity of the resulting degradation products. Even further, recycling and regeneration studies were performed, demonstrating its efficient reuse for 4 consecutive cycles without further treatment, and its subsequent successful regeneration by simply washing the material with a NaCl solution.

Site-selective etching and conversion of bismuth-based Metal–Organic frameworks by oxyanions enables efficient and selective adsorption via robust coordination bonding

Anisotropic etching and conversion of MOF micro/nanostructures results in innovative structures and regulates properties. However, the anisotropic higher-order construction of MOFs remains a major challenge. Here, for the first time, we report the preparation of two unprecedented Bi-MOF (CAU-17) derivative structures via facile chemical etching and simultaneous conversion on solid CAU-17 microrods by reaction with Te- and Se-containing oxyanions. The TeOx2−-mediated hollow tubular structures are obtained via unique splitting, self-welding, and dissolution processes, a tube-forming mechanism never before seen in MOFs. In comparison, SeOx2− ions tend to etch CAU-17 into hierarchical sponge-like structures assembled from fine nanoparticles. DFT calculations, XANES modeling, and EXAFS fittings suggest that the site-selective coordination of oxyanions with Bi-O bonds in the Bi-MOF forms robust Bi-O-Te/Se bonds, which in turn leads to an anisotropic structural transition of CAU-17. More interestingly, benefiting from the coordination bond-dominated conversion, CAU-17 is shown to be a superior adsorbent for the selective and irreversible capture of highly radiotoxic oxyanions containing Te and Se from wastewater. These findings provide new insights into the anisotropic etching and conversion mechanism of MOFs by oxyanions and a fundamental understanding for designing advanced MOF-based guest oxyanion adsorbents.

Chitosan synergizes with bismuth-based metal-organic frameworks to construct double S-type heterojunctions for enhancing photocatalytic antimicrobial activity

In recent years, photocatalytic technology has been introduced to develop a new kind antimicrobial agents fighting antibiotic abusing and related drug resistance. The efforts have focused on non-precious metal photocatalysts along with green additives. In the present work, a novel bis-S heterojunctions based on the coupling of polysaccharide (CS) and bismuth-based MOF (CAU-17) s synthesized through a two-step method involving amidation reaction under mild conditions. The as prepared photocatalyst literally extended the light response to the near-infrared region. Owing to its double S-type heterostructure, the lifetime of the photocarriers is significantly prolonged and the redox capacity are enhanced. As a result, the as prepared photocatalyst indicated inhibition up to 99.9 % under 20 min of light exposure against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria as well as drug-resistant bacteria (MRSA). The outstanding photocatalytic performance is attributed to the effective charge separation and migration due to the unique double S heterostructure. Such a double S heterostructure was confirmed through transient photocurrent response, electrochemical impedance spectroscopy tests and electron spin resonance measurements. The present work provides a basis for the simple synthesis of high-performance heterojunction photocatalytic inhibitors, which extends the application of CAU-17 in environmental disinfection and wastewater purification.

Metal-Organic Framework Based Mucoadhesive Nanodrugs for Multifunction Helicobacter Pylori Targeted Eradication, Inflammation Regulation and Gut Flora Protection.

The prevalence of drug-resistant bacteria presents a significant challenge to the antibiotic treatment of Helicobacter pylori (H. pylori), while traditional antimicrobial agents often suffer from shortcomings such as poor gastric retention, inadequate alleviation of inflammation, and significant adverse effects on the gut microbiota. Here, a selenized chitosan (CS-Se) modified bismuth-based metal-organic framework (Bi-MOF@CS-Se) nanodrug is reported that can target mucin through the charge interaction of the outer CS-Se layer to achieve mucosal adhesion and gastric retention. Additionally, the Bi-MOF@CS-Se can respond to gastric acid and pepsin degradation, and the exposed Bi-MOF exhibits excellent antibacterial properties against standard H. pylori as well as clinical antibiotic-resistant strains. Remarkably, the Bi-MOF@CS-Se effectively alleviates inflammation and excessive oxidative stress by regulating the expression of inflammatory factors and the production of reactive oxygen species (ROS), thereby exerting therapeutic effects against H. pylori infection. Importantly, this Bi-MOF@CS-Se nanodrug does not affect the homeostasis of gut microbiota, providing a promising strategy for efficient and safe treatment of H. pylori infection.

Investigation of bismuth-based metal-organic frameworks for effective capture and immobilization of radioiodine gas

In this study, we investigated the use of Bi-mna, a specific type of bismuth metal organic framework (MOF) for the capture and disposal of iodine, a key nuclide of concern in nuclear fuel reprocessing plants and nuclear power plants. To find the suitable form of Bi-mna for the purpose, experiments were performed by synthesizing four different Bi-mna with varying reagent ratios and connecting iodine adsorption and conversion for immobilization. After iodine adsorption and characterization to investigate their adsorption mechanisms, the Bi-mna samples went through conversion for immobilization to fix captured iodine into the adsorbents. The converted materials are characterized to examine their thermal stability. The Bi-2mna, showing the best performance of adsorption and thermal stability after the conversion, was selected to explore its chemical stability. According to the test results, the converted compound showed relatively low leaching rate (3.06 ×10−5 g/m2∙day) compared with other iodine containing waste forms for disposal. Based on the results, we proposed the Bi-2mna as a candidate material as iodine adsorbent as well as waste form precursor. Environmental implicationRadioiodine a key nuclide of concern in nuclear fuel reprocessing plants and nuclear power plants. Once ingested, it is accumulated in thyroid grand, causing negative health effects. Currently, a typical radioiodine adsorbent is silver-based zeolites. Despite a strong affinity to iodine of silver, it has a chemical toxicity that causes a potential issue in disposal. Therefore, it is substantially required to develop new type of adsorbents which are both good for capture and disposal of radioiodine. In this respect, we suggested a bismuth-based metal-organic framework as an alternative adsorbent to manage the life cycle of radioiodine.

In Situ Multicolor Imaging of Photocatalytic Degradation Process of Permanganate on Single Bismuth-Based Metal-Organic Frameworks.

Bismuth-based metal-organic frameworks (Bi-MOFs) have emerged as important photocatalysts for pollutant degradation applications. Understanding the photocatalytic degradation mechanism is key to achieving technological advantage. Herein, we apply dark-field optical microscopy (DFM) to realize in situ multicolor imaging of the photocatalytic degradation process of permanganate (MnO4-) on single CAU-17 Bi-MOFs. Three reaction kinetic processes such as surface adsorption, photocatalytic reduction, and disproportionation are revealed by combining the time-lapsed DFM images with optical absorption spectra, indicating that the photocatalytic reduction of purple MnO4- first produces beige red MnO42- through a one-electron pathway, and then MnO42- disproportionates into yellow MnO2 on CAU-17. Meanwhile, we observe that the deposition of MnO2 cocatalysts enhances the surface adsorption reaction and the photocatalytic reduction of MnO4- to MnO42-. Unexpectedly, it is found that isopropanol as a typical hole scavenger can stabilize MnO42-, avoiding disproportionation and causing the alteration of the photocatalytic reaction pathway from a one-electron avenue to a three-electron (1 + 2) process for producing MnO2 on CAU-17. This research opens up the possibility of comprehensively tracking and understanding the photocatalytic degradation reaction at the single MOF particle level.

Selective capture of uranium by p-block bismuth-based metal–organic framework

Energy shortage severely impedes the advancement of human society and economy. The vigorous development of nuclear energy is a viable solution to address this issue. The escalating depletion of uranium resources necessitates prioritizing the selective extraction of uranyl from seawater and wastewater to ensure the prosperity of nuclear power. A bismuth-based MOF, CAU-17, was synthesized by the one-step solvothermal method for targeted selection of uranyl in the first time. The uranium adsorption tests demonstrated that CAU-17 exhibited a high adsorption capacity of 421.9 mg g−1 (T = 25 °C, pH = 7), exceptional selectivity, outstanding salt tolerance, and favorable stability with 83.6 % of the initial capacity retained after 5 cycles. Through the utilization of XPS and theoretical calculations, it was elucidated that the carboxyl oxygen that connects the Bi played a pivotal role in the binding process between CAU-17 and uranium ions, with bismuth acting as an electron regulator through its bridging effect with carboxyl oxygen. This work not only presents an exceptional uranium adsorption material but also elucidates the role of core metal atoms in MOFs during the binding to uranium process, thereby offering a novel perspective for future advancements in MOFs-based adsorbents.

Rapid and selective removal of radioactive iodide ions from wastewater via bismuth-based metal-organic frameworks

As one of the main components of the nuclear wastewater discharged from Fukushima, the efficient and safe disposal of radioactive 129I- is very urgent. Here, the trapping ability of water-soluble iodine anions is studied through a metal-organic framework of bismuth (Bi-MOF, select CAU-17 as the representative). It is found that CAU-17 achieves efficient capture of I- ions through chemical and physical cooperative adsorption, with a maximum adsorption capacity of up to 268.9 mg g-1. In addition, the adsorbent also exhibits superior adsorption kinetics and selectivity for I- ions and works stably over a wide pH range of 2–12. Density functional theory (DFT) calculations indicate that most I- ions are immobilized by attacking the Bi3+ sites of the CAU-17 ternary channel to form BiOI compounds. Compared with silver-based adsorbent, the prepared Bi-based adsorbent CAU-17 is more economical and practical. In summary, this work demonstrates the promising application of Bi-MOFs for purifying industrial water-soluble radioactive iodide ions.

In situ growth of Bi-MOF on cotton fabrics via ultrasonic synthesis strategy for recyclable photocatalytic textiles.

Bismuth-based metal-organic framework (Bi-MOF) materials have shown potential for treating organic pollutants. In this work, multifunctional textiles were produced by in situ synthesis of CAU-17 on carboxymethylated cotton fabrics by solvothermal and ultrasonic strategies and employed as recyclable photocatalysts. The compositional and structural features of the dense MOF crystal coatings on cotton fibers were confirmed by scanning electron microscopy, X-ray diffraction, and other characterization approaches. Under optimized conditions, the developed functionalized cotton fabrics achieved a photodegradation efficiency of 98.8% under visible light for RhB in water, as well as good recyclability. The described results have provided the basis and reference for the fabrication of MOF-functionalized textiles.

A microporous bismuth-based MOF for efficient separation of acetylene from carbon dioxide.

The separation of acetylene from carbon dioxide is challenging due to their almost identical molecular sizes and volatilities. Metal-organic frameworks (MOFs) in general are strong candidates for the separation of gas mixtures owing to the presence of functional pore surfaces that can selectively capture specific target molecules. Herein, we report a stable and easily synthesized bismuth-based MOF, Bi-BTC, which can achieve the separation of acetylene and carbon dioxide. We performed a detailed analysis of the sorption properties of the Bi-MOF. Bi-BTC shows good adsorption capacities for C2H2 with a capacity of 53.8 cm3 g-1 at 298 K and 1.0 bar, and C2H2/CO2 selectivity of 5.14/7.69 at 298 K and 1.0/0.1 bar. IAST selectivity calculations indicate that Bi-BTC possesses good separation capacity, and dynamic breakthrough experiments were performed to prove the separation of C2H2 and CO2. Bi-MOFs as a group of relatively less studied types of MOFs have interesting adsorption characteristics, and this study on Bi-based MOF will enrich three-dimensional Bi-MOF adsorbents for gas adsorption and separation applications.

Enhanced cycloaddition between CO2 and epoxide over a bismuth-based metal organic framework due to a synergistic photocatalytic and photothermal effect

The cycloaddition reaction between CO2 and epoxide is an efficient way to convert CO2 into high value-added chemicals. Therefore, it is particularly important to develop efficient catalysts that can catalyze the reaction under mild conditions. In this work, a metal–organic framework (Bi-HHTP, consisting of bismuth (Bi) as metal dots and 2,3,6,7,10,11-hexahydroxy-triphenylene (HHTP) as organic linkers) with zigzagging corrugated topology was successfully synthesized, which shows excellent catalytic activity under visible light irradiation. Various characterizations suggest that the excellent activity is derived from the following reasons: (1) the abundant exposed Bi sites provide Lewis sites for adsorption of epoxides and CO2; (2) the free holes produced over Bi-HHTP under light irradiation which could oxidize epoxide, which consequently facilitateing the subsequent ring-opening reaction; and (3) the existence of synergistic photocatalytic and photothermal effect in Bi-HHTP. This study provides a new avenue of developing bismuth-based metal organic frameworks to promote the efficiency of cycloaddition of CO2 under mild conditions.