Synthesis of MOFs/GO composite for corrosion resistance application on carbon steel

Smart Textile: Electrohydrodynamic Jet Printing of Ionic Liquid-Functionalized Cu3(HHTP)2 Metal-Organic Frameworks for Gas-Sensing Applications

This study presents the development and characterization of a smart textile gas sensor based on the integration of ionic liquid (IL)-functionalized Cu3(HHTP)2 metal-organic frameworks (MOFs), using electrohydrodynamic jet (e-jet) printing. The sensor was designed for the detection of nitric oxide (NO) gas, a critical target in various environmental and safety applications. Cu3(HHTP)2 MOFs were synthesized and subsequently functionalized with 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIM+ Otf-) ionic liquid to enhance their chemiresistive performance toward NO gas. The functionalized MOF was then e-jet printed onto electrospun polylactic acid (PLA) substrates to fabricate smart textile sensors. The IL-functionalized Cu3(HHTP)2 sensors demonstrated a 582× increase in conductivity compared to previously reported MOF-based sensors. Additionally, IL functionalization enhanced sensor sensitivity, with a response increasing from less than 5% in pristine MOF@PLA sensors to approximately 570% at 100 ppm of NO gas. Performance was systematically evaluated across NO concentrations ranging from 5 to 300 ppm, achieving a theoretical limit of detection of 3.7 ppm. The sensors exhibited partial reversibility and retained functionality over extended periods and under humid conditions. Comprehensive analyses using SEM, EDX, FTIR, and XRD were performed to assess the crystallinity of MOF deposits and elucidate the sensing mechanism. These findings highlight the potential of e-jet printing of IL-functionalized MOFs for the development of advanced, flexible gas sensors with applications in both civilian and military settings and implications for personal protective wearable technologies.

Synthesis and evaluation of CuNi-MOF as a corrosion inhibitor of AISI 304 and 316 stainless steel in 1N HCl solution

A bimetallic organic framework (CuNi-MOF) was synthesized as a corrosion inhibitor using the solvothermal method. The effectiveness of the inhibitor in corrosion prevention of AISI 304 and 316 in 1N hydrochloric acid solution at room temperature was evaluated using weight loss measurements, electrochemical methods, and surface characterization techniques. The formation of CuNi-MOF protective layer on the stainless-steel surface was confirmed through Field Emission Scanning Electron Microscopes (FESEM), Energy Dispersive Spectroscopy (EDS), and X-Ray Diffraction (XRD) analysis. The result showed that the synthesized inhibitor with a concentration of 150 mg/L could improve the corrosion inhibition of studied materials by up to 87.12 % for AISI 304 and 91.9 % for AISI 316, respectively. The potentiodynamic polarization data indicated the studied inhibitor acts as an anodic type inhibitor and EIS investigations revealed a significant increase in polarization resistance with addition of 150 mg/L CuNi-MOF. The study of adsorption energy (ΔGads 0) revealed the Langmuir adsorption isotherm prevails in CuNi-MOF adsorption, encompassing both chemisorption and physisorption mechanisms.

Revolutionizing environmental cleanup: the evolution of MOFs as catalysts for pollution remediation

The global problem of ecological safety and public health necessitates, the development of new sustainable ideas for pollution remediation. In recent development, metal-organic frameworks (MOF) are the emerging technology with remarkable potential, which have been employed in environmental remediation. MOFs are networks that are created by the coordination of metals or polyanions with ligands and contain organic components that can be customized. The interesting features of MOFs are a large surface area, tuneable porosity, functional diversity, and high predictability of pollutant adsorption, catalysis, and degradation. It is a solid material that occupies a unique position in the war against environmental pollutants. One of the main benefits of MOFs is that they exhibit selective adsorption of a wide range of pollutants, including heavy metals, organics, greenhouse gases, water and soil. Only particles with the right combination of pore size and chemical composition will achieve this selectivity, derived from the high level of specificity. Besides, they possess high catalytic ability for the removal of pollutants by means of different methods such as photocatalysis, Fenton-like reactions, and oxidative degradation. By generating mobile active sites within the framework of MOFs, we can not only ensure high affinity for pollutants but also effective transformation of toxic chemicals into less harmful or even inert end products. However, the long-term stability of MOFs is becoming more important as eco-friendly parts are replaced with those that can be used repeatedly, and systems based on MOFs that can remove pollutants in more than one way are fabricated. MOFs can reduce waste production, energy consumption as compared to the other removal process. With its endless capacities, MOF technology brings a solution to the environmental cleansing problem, working as a flexible problem solver from one field to another. The investigation of MOF synthesis and principles will allow researchers to fully understand the potential of MOFs in environmental problem solving, making the world a better place for all of us.

Novel Schiff's base-assisted synthesis of metal-ligand nanostructures for multi-functional applications: Detection of catecholamines/antibiotics, removal of tetracycline, and antifungal treatment against plant pathogens

The development of nanozymes (NZ) for the simultaneous detection of multiple target chemicals is gaining paramount attention in the field of food and health sciences, and waste management industries. Nanozymes (NZ) effectively compensate for the environmental vulnerability of natural enzymes. Considering the development gap of NZ with diverse applications, we synthesized versatile Schiff's base ligands following a facile route and readily available starting reagents (glutaraldehyde, aminopyridines). DPDI, one of the synthesized ligands, readily reacted with transition metal ions (Cu+2, Ag+1, Zn+2 in specific) under ambient conditions, yielding the corresponding nanoparticles/MOF. The structures of ligands and their products were confirmed using various analytical techniques. The enzymatic efficacy of DPDI-Cu (km 0.25 mM=, Vmax = 10.75 µM/sec) surpassed Tremetese versicolor laccase efficacy (km 0. 5 mM=, Vmax = 2.15 µM/sec). Additionally, DPDI-Cu proved resilient to changing pH, temperature, ionic strength, organic solvent, and storage time compared to laccase and provided reusability. DPDI-Cu proved promising for colorimetric detection of dopamine, epinephrine, catechol, tetracycline, and quercetin. The mechanism of oxidative detection of TC was studied through LC/MS analysis. DPDI-Cu-bentonite composite efficiently adsorbed tetracycline with maximum Langmuir adsorption of 208 mg/g. Moreover, DPDI/Cu and DPDI-Ag nanoparticles possessed antifungal activity exhibiting a minimum inhibitory concentration of 400 µg/mL and 3.12 µg/mL against Aspergillus flavus. Florescent dye tracking and SEM/TEM analysis confirmed that DPDI-Ag caused disruption of the plasma membrane and triggered ROS generation and apoptosis-like death in fungal cells. The DPDI-Ag coating treatment of wheat seeds confirmed the non-phytotoxicity of Ag-NPs.

Eco-Friendly Sustainable and Responsive High-Performance Benzotriazole-Metal Organic Frameworks/Silica Composite Coating with Active/Passive Corrosion Protection on Copper

Coatings with only passive protection cannot offer long-term anticorrosion on metals. Eco-friendly sustainable and responsive coating for active/passive corrosion protection is desirable to extend the service life of metals. Here, benzotriazole (BTA)-metal organic frameworks (Cu-MOFs, UiO-66) were embedded in silica (SiO2) coating by one-step electrodeposition on copper. Combined with passive capability of MOFs and active protection of BTA inhibitor, the composite coating (BTA-MOF/SiO2) exhibited high and stable corrosion resistance, confirmed by microstructure characterizations and electrochemical tests. As a result, the as-prepared composite coating exhibited superhydrophobicity with a water contact angle of 154.2°. With loading of BTA-MOF in SiO2 coating, the impedance modulus at 0.01 Hz increased by ∼10-fold and the corrosion current density decreased to 3.472 × 10-9 A·cm-2. Immersion and salt spray tests confirmed the long-term protection of the composite coating. The responsive release of BTA inhibitor endows the coating with a responsively anticorrosive behavior. The active-passive ability makes the coating a good candidate for protection on metals used in highly salty environments.

Nanocomposite Coatings for Anti-Corrosion Properties of Metallic Substrates

Nanocomposites are high-performance materials with exceptional characteristics that possess properties that their individual constituents, by themselves, cannot provide. They have useful applications in many fields, ranging from membrane processes to fuel cells, biomedical devices, and anti-corrosion protection. Well-tailored nanocomposites are promising materials for anti-corrosion coatings on metals and alloys, exhibiting simple barrier protection or even smart auto-responsive and self-healing functionalities. Nanocomposite coatings can be prepared by using a large variety of matrices and reinforcement materials, often acting in synergy. In this context, recent advances in the preparation and characterization of corrosion-resistant nanocomposite coatings based on metallic, polymeric, and ceramic matrices, as well as the incorporation of various reinforcement materials, are reviewed. The review presents the most important materials used as matrices for nanocomposites (metals, polymers, and ceramics), the most popular fillers (nanoparticles, nanotubes, nanowires, nanorods, nanoplatelets, nanosheets, nanofilms, or nanocapsules), and their combinations. Some of the most important characteristics and applications of nanocomposite coatings, as well as the challenges for future research, are briefly discussed.

Enhancing Self-Healing and Adhesion Bonding Properties: Investigating the Promising Potential of Ce-ZIF8 MOF Hybrid Thin Films as pH-Responsive Nanocoatings

Further modification of the pre-treated steel surface with cerium conversion coating was performed using a novel porous coordination polymer (PCP) based on zeolitic imidazole framework-8 (ZIF8) in order to reduce the defect and disorders of the surface. The treated mild steels (MS) with Ce (MS/Ce) and Ce-ZIF8 (MS/Ce-ZIF8) were characterized by the GIXRD, Raman, and FT-IR, and via contact angle and FE-SEM, their surface features were investigated. The protection performance of the samples against corrosion was evaluated in the saline solution media using electrochemical impedance spectroscopy (EIS, in the long term) and polarization tests. The results evidenced that applying the ZIF8 nanoparticles onto the Ce-treated steel surface increased the total resistance value after 24 h of immersion (49.47%). Afterward, the ZIF8-modified coating (MS/Ce and MS/Ce-ZIF8) impact on the epoxy coating protection function was characterized by EIS (in the scratched form), salt spray (5 wt % salts), cathodic disbonding (at 25 °C), and pull-off tests. The EIS outcomes of the scratched coatings proved approximately a 51.29% increase in R_t of the MS/Ce-ZIF8/EC sample compared with the MS/EC sample after 24 h of immersion. The cathodic disbonding test results after 24 h of exposure revealed that the delamination area of the coating decreased in the modified sample, and the delamination radius of the epoxy coating was about 4.78, 2.96, and 2.0 mm for the MS/EC, MS/Ce/EC, and MS/Ce-ZIF8/EC samples, respectively.

Recent Progress of Advanced Conductive Metal-Organic Frameworks: Precise Synthesis, Electrochemical Energy Storage Applications, and Future Challenges

Metal-organic frameworks (MOFs) with diverse composition, tunable structure, and unique physicochemical properties have emerged as promising materials in various fields. The tunable pore structure, abundant active sites, and ultrahigh specific surface area can facilitate mass transport and provide outstanding capacity, making MOFs an ideal active material for electrochemical energy storage and conversion. However, the poor electrical conductivity of pristine MOFs severely limits their applications in electrochemistry. Developing conductive MOFs has proved to be an effective solution to this problem. This review focuses on the design and synthesis of conductive MOF composites with judiciously chosen conducting materials, pristine MOFs, and assembly methods, as well as the preparation of intrinsically conductive MOFs based on building 2D π-conjugated structures, introducing mixed-valence metal ions/redox-active ligands, designing π-π stacked pathways, and constructing infinite metal-sulfur chains (-M-S-)_∞ . Furthermore, recent progress and challenges of conductive MOFs for energy storage and conversion (supercapacitors, Li-ion batteries, Li-S batteries, and electrochemical water splitting) are summarized.

Rational design of ZnO@ZIF-8 nanoarrays for improved electrochemical detection of H2O2

Core–shell ZnO@ZIF-8 nanoarrays demonstrate remarkable electrochemical performance for detection of H2O2.

Application of Metal-Organic Framework-Based Composites for Gas Sensing and Effects of Synthesis Strategies on Gas-Sensitive Performance

Gas sensing materials, such as semiconducting metal oxides (SMOx), carbon-based materials, and polymers have been studied in recent years. Among of them, SMOx-based gas sensors have higher operating temperatures; sensors crafted from carbon-based materials have poor selectivity for gases and longer response times; and polymer gas sensors have poor stability and selectivity, so it is necessary to develop high-performance gas sensors. As a porous material constructed from inorganic nodes and multidentate organic bridging linkers, the metal-organic framework (MOF) shows viable applications in gas sensors due to its inherent large specific surface area and high porosity. Thus, compounding sensor materials with MOFs can create a synergistic effect. Many studies have been conducted on composite MOFs with three materials to control the synergistic effects to improve gas sensing performance. Therefore, this review summarizes the application of MOFs in sensor materials and emphasizes the synthesis progress of MOF composites. The challenges and development prospects of MOF-based composites are also discussed.

Amino-functionalized Ti3C2Tx loading ZIF-8 nanocontainer@benzotriazole as multifunctional composite filler towards self-healing epoxy coating

It is difficult for Ti₃C₂T_x-containing epoxy coatings to prevent electrochemical corrosion at the metal/coating interface after long-term exposure to corrosive environments. Thus, endowing Ti₃C₂T_x-containing epoxy coatings with self-healing function and good wear resistance is very significant. Here, a novel self-healing epoxy coating (f-Ti₃C₂T_x-ZB@EP) is designed via incorporating with amino-functionalized Ti₃C₂T_x loading 2-methylimidazole zinc salt (ZIF-8) nanocontainer@benzotriazole (f-Ti₃C₂T_x-ZB) multifunctional composite filler, and its anti-corrosion and tribological properties are evaluated in detail. The as-prepared f-Ti₃C₂T_x-ZB@EP shows an order of magnitude enhancement in coating resistance (R_c) and achieves self-healing function under severe environment, which are attributed to the synergistic effect of passive and active protection. Specially, the change of pH value caused by electrochemical corrosion could induce the nanocontainer to release BTA, thereby forming corrosion inhibition films on the coating/metal interface. Besides, the wear rate of f-Ti₃C₂T_x-ZB@EP is decreased by one order of magnitude because of the lubrication effect of Ti₃C₂T_x at the friction interface and the high resistance to plastic deformation of epoxy composite coating. Therefore, f-Ti₃C₂T_x-ZB@EP with better self-healing, anti-corrosion and tribological properties is equipped with long-term metal protection ability and enlightens a thought-provoking idea for corrosion and wear resistance.