The Co-MOF-74 modified with N,N′-Dihydroxypyromellitimide for selective, solvent free aerobic oxidation of toluene

General and Facile Synthesis of Co/CoO Nanoparticals Supported by Nitrogen-Doped Graphenic Networks as Efficient Oxygen Electrocatalyst for Zn-Air Batteries

Reasonable design of low-cost, high-efficiency and stable bifunctional oxygen electrocatalysts is of great significance to improve the reaction efficiency of Zn-air batteries, which is still a huge challenge. Here, we report a highly efficient bifunctional oxygen electrocatalyst with three-dimensional (3D) N-doped graphene network-supported cobalt and cobalt oxide nanoparticles (Co/CoO-NG), which can be in situ synthesized by inducing metal ions on metal plates via graphene oxide as an inducer. This 3D network structure and open active center show excellent bifunctional oxygen electrocatalytic activity under alkaline conditions, and can be used as an air electrode in rechargeable Zn-air batteries, with significantly better power density (244.28 mW cm-2) and stability (over 340 h) than commercial Pt/C+RuO2 mixtures. This work is conducive to advancing the practical application of graphene-based materials as air electrodes for rechargeable zinc-air batteries.

A new strategy for PET depolymerization: Application of bimetallic MOF-74 as a selective catalyst

Large-volume production of poly(ethylene terephthalate) (PET), especially in the form of bottles and food packaging containers, causes problems with polymer waste management. Waste PET could be recycled thermally, mechanically or chemically and the last method allows to obtain individual monomers, but most often it is carried out in the presence of homogeneous catalysts, that are difficult to separate and reuse. In view of this, this work reports for the first time, application of bimetallic MOF-74 - as heterogeneous catalyst - for depolymerization of PET with high monomer (bishydroxyethyl terephthalate, BHET) recovery. The effect of type and amount of second metal in the MOF-74 (Mg/M) was systematically investigated. The results showed increased activity of MOF-74 (Mg/M) containing Co2+, Zn2+ and Mn2+ as a second metal, while the opposite correlation was observed for Cu2+ and Ni2+. It was found that the highest catalytic activity was demonstrated by the introduction of Mg-Mn into MOF-74 with ratio molar 1:1, which resulted in complete depolymerization of PET and 91.8% BHET yield within 4 h. Furthermore, the obtained catalyst showed good stability in 5 reaction cycles and allowed to achieve high-purity BHET, which was confirmed by HPLC analysis. The as-prepared MOF-74 (Mg/Mn) was easy to separate from the post-reaction mixture, clean and reuse in the next depolymerization reaction.

Cobalt-Based Metal Organic Frameworks as Solids Catalysts for Oxidation Reactions

Metal organic frameworks (MOFs) are porous crystalline solids whose frameworks are constituted by metal ions/nodes with rigid organic linkers leading to the formation of materials having high surface area and pore volume. One of the unique features of MOFs is the presence of coordinatively unsaturated metal sites in their crystalline lattice that can act as Lewis acid sites promoting organic transformations, including aerobic oxidation reactions of various substrates such as hydrocarbons, alcohols, and sulfides. This review article summarizes the existing Co-based MOFs for oxidation reactions organized according to the nature of substrates like hydrocarbon, alcohol, olefin, and water. Both aerobic conditions and peroxide oxidants are discussed. Emphasis is placed on comparing the advantages of using MOFs as solid catalysts with respect to homogeneous salts in terms of product selectivity and long-term stability. The final section provides our view on future developments in this field.

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.

The Co-N-C Catalyst Synthesized With a Hard-Template and Etching Method to Achieve Well-Dispersed Active Sites for Ethylbenzene Oxidation

Biomass obtained from organic residues gradually becomes one of the optimal renewable feedstock of value added chemicals. Herein, the Co-N-C catalyst was prepared via a hard-template and etching method using the casein as C and N sources, magnesium oxide as the template, and cobalt porphyrin as the metal precursor. The obtained Co-N-C catalyst exhibited excellent catalytic performance for selective oxidation of ethylbenzene with a conversion rate of 96.5% under mild conditions. Moreover, the catalysts were investigated by techniques such as BET, XRD, Raman, transmission electron microscopic (TEM), and X-ray photoelectron spectroscopy (XPS). The results showed that the etching progress could improve the dispersion of Co and the exposure of active sites. Herein, the efficient oxidation of ethylbenzene was attributed to the well-dispersed Co-N species and the increased specific surface area.