Co-MOF-74 based Co3O4/cellulose derivative membrane as dual-functional catalyst for colorimetric detection and degradation of phenol.

Smart nanomaterials that can simultaneously detect and eliminate contaminants in water environment are significant for health protection. To achieve such goal, Co-MOF-74 was in-situ assembled on regenerated cellulose membranes followed by calcination process, thus achieving dual-functional Co3O4/cellulose derivative membrane (Co3O4/CDM) catalyst. The Co3O4 morphology was readily controlled by further recrystallization of the deposited MOF precursor. Combining the high enrichment ability of cellulose membrane and outstanding peroxidase-active of Co3O4, the fast color reaction for phenol was accomplished within 10 min by Co3O4/CDM with the assistance of H2O2 and 4-aminoantipyrine (4-AAP). Moreover, the Co3O4/CDM also portrayed an excellent degradation property for phenol elimination via sulfate radical-advanced oxidation processes (SR-AOPs). The degradation efficiency of phenol reached 93% in 20 min, and the possible mineralization mechanism was proposed based on the XPS and LC-MS analysis. Thus, Co-MOF-74 derived Co3O4/CDM shows excellent properties in aiding the colorimetric detection and degradation of phenol in aqueous solutions.

Humidity-Mediated Anisotropic Proton Conductivity through the 1D Channels of Co-MOF-74.

Large Co-MOF-74 crystals of a few hundred micrometers were prepared by solvothermal synthesis, and their structure and morphology were characterized by scanning electron microscopy (SEM), IR, and Raman spectroscopy. The hydrothermal stability of the material up to 60 °C at 93% relative humidity was verified by temperature-dependent XRD. Proton conductivity was studied by impedance spectroscopy, using a single crystal. By varying the relative humidity (70-95%), temperature (21-60 °C), and orientation of the crystal relative to the electrical potential, it was found that proton conduction occurs predominantly through the linear, unidirectional (1D) micropore channels of Co-MOF-74, and that water molecules inside the channels are responsible for the proton mobility by a Grotthuss-type mechanism.

Rod-like Co based metal-organic framework embedded into mesoporous carbon composite modified glassy carbon electrode for effective detection of pyrazinamide and isonicotinyl hydrazide in biological samples.

Herein, we report a novel composite fabricated via embedding rod-like Co based metal-organic framework (Co-MOF-74) crystals into MC matrix for the first time. The introduction of MC astricts the size of Co-MOF-74 crystals, enlarges the pore size and improves the electrical conductivity, which lead to the good electrochemical properties of the composite. The fabricated sensor based on Co-MOF-74@MC exhibits superior electrocatalytic activity toward the reduction of pyrazinamide (PZA) and the oxidation of isonicotinyl hydrazide (INZ). Under optimized conditions, the sensor shows two linear ranges from 0.3 to 46.5 µM and 46.5-166.5 µM with a high sensitivity of 7.2 µA µM-1 cm-2 and a detection limit of 0.21 µM for the determination of PZA. The electroanalytical sensing of INZ also gives two linear ranges of 0.15-1.55 µM and 1.55-592.55 µM with a detection limit of 0.094 µM. The mechanism involved was also discussed, briefly. The sensor is assessed toward the detection of PZA and INZ in human serum and urine samples. Recovery values varied from 97.08 to 103.20% for PZA sensing and 96.67-102.90% for INZ sensing, revealing the promising practicality of sensor for PZA and INZ detection.

Shape-Defined Hollow Structural Co-MOF-74 and Metal Nanoparticles@Co-MOF-74 Composite through a Transformation Strategy for Enhanced Photocatalysis Performance.

In recent years, metal-organic frameworks (MOFs) have received extensive interest because of the diversity of their composition, structure, and function. To promote the MOFs' function and performance, the construction of hollow structural metal-organic frameworks and nanoparticle-MOF composites is significantly effective but remains a considerable challenge. In this article, a transformation strategy is developed to synthesize hollow structural Co-MOF-74 by solvothermal transformation of ZIF-67. These Co-MOF-74 particles exhibit a double-layer hollow shell structure without remarkable shape change compared to original ZIF-67 particles. The formation of hollow structure stemmed from the density difference of Co between ZIF-67 and Co-MOF-74. By this strategy, hollow structural Co-MOF-74 with different sizes and shapes are obtained from corresponding ZIF-67, and metal nanoparticles@Co-MOF-74 is synthesized by corresponding nanoparticles@Co-ZIF-67. To verify the structural advantages of hollow structural Co-MOF-74 and Ag nanoparticles@Co-MOF-74, photocatalytic CO2 reduction is used as a model reaction. Conventionally synthesized Co-MOF-74 (MOF-74-C), hollow structural Co-MOF-74 synthesized by transformation method (MOF-74-T) and Ag nanoparticles@Co-MOF-74 (AgNPs@MOF-74) are used as cocatalysts in this reaction. As a result, the cocatalytic activity of MOF-74-T and AgNPs@MOF-74 is 1.8 times and 3.8 times that of MOF-74-C, respectively.

Preparation of Fe-Co based MOF-74 and its effective adsorption of arsenic from aqueous solution.

To obtain a cost-effective adsorbent for the removal of arsenic in water, a novel nanostructured Fe-Co based metal organic framework (MOF-74) adsorbent was successfully prepared via a simple solvothermal method. The adsorption experiments showed that the optimal molar ratio of Fe/Co in the adsorbent was 2:1. The Fe2Co1 MOF-74 was characterized by various techniques and the results showed that the nanoparticle diameter ranged from 60 to 80 nm and the specific surface area was 147.82 m2/g. The isotherm and kinetic parameters of arsenic removal on Fe2Co1 MOF-74 were well-fitted by the Langmuir and pseudo-second-order models. The maximum adsorption capacities toward As(III) and As(V) were 266.52 and 292.29 mg/g, respectively. The presence of sulfate, carbonate and humic acid had no obvious effect on arsenic adsorption. However, coexisting phosphate significantly hindered the removal of arsenic, especially at high concentrations (10 mmol/L). Electrostatic interaction and hydroxyl and metal-oxygen groups played important roles in the adsorption of arsenic. Furthermore, the prepared adsorbent had stable adsorption ability after regeneration and when used in a real-water matrix. The excellent adsorption performance of Fe2Co1 MOF-74 material makes it a potentially promising adsorbent for the removal of arsenic.