A Co-MOF-derived oxygen-vacancy-rich Co3O4-based composite as a cathode material for hybrid Zn batteries

Accelerated redox conversion of an advanced Zn//Fe-Co3O4 battery by heteroatom doping

Herein, Fe-doped Co₃O₄ (Fe-Co₃O₄) was prepared to solve the issues of poor electrical conductivity and the lack of active sites in Co₃O₄ materials. Due to having similar radius and physical/chemical properties to Co, Fe is an ideal choice for doping Co₃O₄, as it can improve intrinsic conductivity without causing severe lattice distortion. Oxygen vacancies are gradually formed as doping reactions occur to maintain electric neutrality. Owing to the merits of oxygen vacancies in Co₃O₄, the distribution of the electrons is changed, thus optimizing the material's intrinsic charge/ion states and modifying the band gap by introducing impurity levels. Moreover, the surface area of Fe-Co₃O₄ is 1.5 times larger than that of the original material. The synergistic effect promotes the electrochemical oxidation reduction reaction and improves the capacitance and cycling stability. Finally, such an advanced Zn//Fe-Co₃O₄ battery exhibits a discharge-specific capacity of 171.97 mA h g^-1, nearly eight times higher than that of the previous Zn//Co₃O₄ battery (22.38 mA h g^-1). In addition, the attenuation of the capacity was almost negligible after 9000 cycles.

MOF-derived MnO@C with high activity for electric field-assisted catalytic oxidation of aqueous pollutants

The activation of oxygen (O₂) under room condition is important for the utilization of air to perform oxidation. Here, we report a porous carbon-encapsulated MnO (MnO@C) derived from Mn metal-organic framework (MOF)grown in-situ on a graphite felt (GF) support. The MnO@C exhibits superior catalytic activity in an electric field-assisted catalytic oxidation system for the degradation of organic pollutants under room condition. The catalytic oxidation reaction applies a surface reaction pathway in which the surface-bound chemisorbed oxygen species are electro-oxidized and then involved in the oxidation of co-adsorbed organic pollutants. The abundant oxygen vacancies and oxygenated functional groups in MnO@C provide active sites for the chemisorption of O₂, and its conductive mesoporous structure allows facile electrons and mass transfer. As a result, the MnO@C/GF catalyst displays quite high turnover frequency (TOF) value as 0.038 mg-TOC mg-MnO^-1 min^-1, which is 6.66 times higher than that of the MnO/GF catalyst prepared by impregnation method as a comparison. With the aid of + 1.0 V of positive electric field, the catalytic oxidation system exhibits extensive effectiveness in mineralizing a variety of dyes, pharmaceuticals, personal care products, and phenolic compounds under room condition with significantly enhanced biodegradability.

Structural regulation of Co-based coordination polymers by adjusting solvent polarity toward electrocatalytic hydrogen evolution performance

A slight change of the solvent plays an important role in the synthesis process, and a small change in the crystal structure can also lead to a large difference in performance.

Recent Advances on MOF Derivatives for Non-Noble Metal Oxygen Electrocatalysts in Zinc-Air Batteries

Oxygen electrocatalysts are of great importance for the air electrode in zinc-air batteries (ZABs). Owing to the high specific surface area, controllable pore size and unsaturated metal active sites, metal-organic frameworks (MOFs) derivatives have been widely studied as oxygen electrocatalysts in ZABs. To date, many strategies have been developed to generate efficient oxygen electrocatalysts from MOFs for improving the performance of ZABs. In this review, the latest progress of the MOF-derived non-noble metal-oxygen electrocatalysts in ZABs is reviewed. The performance of these MOF-derived catalysts toward oxygen reduction, and oxygen evolution reactions is discussed based on the categories of metal-free carbon materials, single-atom catalysts, metal cluster/carbon composites and metal compound/carbon composites. Moreover, we provide a comprehensive overview on the design strategies of various MOF-derived non-noble metal-oxygen electrocatalysts and their structure-performance relationship. Finally, the challenges and perspectives are provided for further advancing the MOF-derived oxygen electrocatalysts in ZABs.

Activity manifestation via architectural manipulation by cubic silica-derived Co3O4 electrocatalysts towards bifunctional oxygen electrode performance

A KIT-6-derived Co3O4 material demonstrates superior bifunctional activity due to its higher densities of Co3+ and Co2+ sites.

Micro-nano NiO-MnCo2O4 heterostructure with optimal interfacial electronic environment for high performance and enhanced lithium storage kinetics

This manuscript provides an in situ synthesis method for the self-assembly of a heterostructured NiO-MnCo2O4 micro-nano composite with a poriferous shell. The special shell structure effectively alleviated the volume variation and subsequently enhanced the diffusivity of ions in the cycling process for cyclic stability. The inner spaces among the stacked nanoparticles are conducive to electrolyte infiltration and the transfer of ion/electrons with low concentration polarization. Consequently, the optimized NiO-MnCo2O4 exhibited excellent cycle stability (718.8 mA h g-1 after 1000 cycles at 2 A g-1) and highly recoverable rate performance. On gaining insight into the heterointerface structure, it was indicated that the optimal interfacial electronic environment in the presence of the nickel content plays a key role in creating lattice defects and active sites to increase the ion diffusion rate, electron conductivity and unlock extra pseudocapacitance for ion storage. The excellent capabilities from the optimal heterointerface environment will promote the development of high-energy applications of LIBs.

A novel cadmium metal–organic framework-based multiresponsive fluorescent sensor demonstrating outstanding sensitivities and selectivities for detecting NB, Fe3+ ions and Cr2O72− anions

A Cd(ii) metal–organic framework (MOF) [Cd₃(L)(NTB)₂(DMA)₂]·2DMA was solvothermal prepared in the presence of ligand L (L = (E)-4,4′-(ethene-1,2-diyl)bis[(N-pyridin-3-yl)benzamide]) and ligand H₃NTB (H₃NTB = 4,4′,4′′-nitrilotribenzoic acid).