Cyclohexane oxidation using advanced oxidation processes with metals and metal oxides as catalysts: a review

Selective oxidation of cyclohexane has gained substantial interest in the field of research due to the prominence of its products in industrial processes. Particularly, advanced oxidation processes (AOPs) constitute a positive technology for the oxidation of cyclohexane owing to their high oxidation potentials and environmental benign properties. This review entails to address the progress made in advanced oxidation of cyclohexane over nanostructured metals and metal oxides catalysts. The main focus is directed toward the photocatalysis, Fenton oxidation and ozonation as advanced oxidation processes. Mainly, the fundamental principles, prime factors of the AOPs in conjunction with metal and metal oxide catalysts and the mechanistic insight toward the oxidation of cyclohexane are highlighted. The affirmative effects of the metals and metal oxide catalysts mainly focusing on particle size, structure and elemental composition is stressed. Lastly, the advantages and disadvantages of the AOPs and the strategic approaches to counter the disadvantages are also clearly elucidated.

Recent advances on preparation and environmental applications of MOF-derived carbons in catalysis

Carbon materials derived from metal organic frameworks (MOFs) have excellent properties of high surface area, high porosity, adjustable pore size, high conductivity and stability, and their applications in catalysis have become a rapidly expanding research field. In this review, we have summarized the synthesis strategies of MOF-derived carbons with different physical and chemical properties, obtained through direct carbonization, co-pyrolysis and post-treatment. The potential applications of derived carbons, especially monometal-, bimetal-, nonmetal-doped and metal-free carbons in organo-catalysis, photocatalysis and electrocatalysis are analyzed in detail from the environmental perspective. In addition, the improvement of catalytic efficiency is also considered from the aspects of increasing active sites, enhancing the activity of reactants and promoting free electron transfer. The function and synergy of various species of the composites in the catalytic reaction are summarized. The reaction paths and mechanisms are analyzed, and research ideas or trends are proposed for further development.

Metal-Organic Framework-Derived Strategy for Improving Catalytic Performance of a Chromia-Based Catalyst in the Chlorine/Fluorine Exchange Reactions for Unsaturated Fluorocarbons

Hydrofluoroolefins (HFOs) and cyclic hydrofluorocarbons (c-HFCs) have been the most favored alternatives of the ozone depletion substances; however, because of the poor performance of the present chlorine/fluorine (Cl/F) exchange catalysts, the development and production of HFOs and c-HFCs are hindered. Here, we first report a novel and facile route to fabricate high-performance Cl/F exchange catalysts via a metal-organic framework (MOF) carbonization method. The MOF-derived catalyst not only has high selectivity but also can significantly lower the reaction temperature. Moreover, benefiting from the stable structure and coke-inhibiting ability, the MOF-derived catalyst has a long service life compared with the traditional precipitation method. Furthermore, the nanoscopic MOF-derived catalyst can greatly reduce the Cr dosage, which would help to minimize the risk of Cr contamination.

Photoelectrochemical water-splitting over a surface modified p-type Cr2O3 photocathode

H₂ generation via solar photoelectrochemical water-splitting by Cr₂O₃ was successfully realized by surface modification with TiO₂ and the following Pt deposition.

Bi2S3 nanorod-stacked hollow microtubes self-assembled from bismuth-based metal-organic frameworks as advanced negative electrodes for hybrid supercapacitors

Bismuth sulfide (Bi2S3) with a lamellar structure has emerged as a promising negative electrode material for supercapacitors (SCs) due to its high theoretical specific capacity. Meanwhile, the improvement of electrochemical properties strongly depends on the size, shape and morphologies of Bi2S3 nanomaterials. Herein, the hierarchical Bi2S3 nanorod-stacked hollow microtubes are self-assembled through a facile self-sacrificing template strategy from bismuth-based metal-organic framework microprisms. Benefiting from the unique structures with a large specific surface area (54.3 m2 g-1), the as-prepared Bi2S3 exhibits an ultrahigh specific capacity (532 C g-1 at 1 A g-1) as a negative electrode for SCs, outperforming other reported Bi2S3 materials.