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•The BN-based nanomaterials present the outstanding removal percentage of organic pollutants.•The BN-based nanomaterials have satisfactory sorption capacities for heavy metal ...ions.•The removal processes of heavy metal ions were mainly attributed to surface complexation.•The interaction mechanism between BN and organic compounds was π-π interaction.
Water pollution, a worldwide issue for the human society, has raised global concerns on environmental sustainability, calling for high-performance materials in effective pollution treatments. Boron nitride (BN) with a structure similar to graphene possesses many extraordinary properties such as high surface areas, high oxidization resistance at high temperature, and high chemical stability. This review presents the outstanding removal percentage and environmental restoration of BN-based nanomaterials for the elimination of various pollutants from the last ten years. Notably, recent advances in the removal of organic/inorganic pollutants and interaction mechanism are outlined. BN-based materials can not only preferably remove contaminants, but also can be directly regenerated by burning in air. The BN-based materials have satisfactory sorption capacities for inorganic pollutants (e.g. heavy metal ions) and organic pollutants (e.g. dyes and pharmaceutical molecules). The interaction mechanisms between pollutants and BN-based materials are mainly surface complexation, π-π stacking, and electrostatic interactions. This paper is beneficial to further comprehend the interactions of pollutants with BN-based materials, which is also helpful for the improvement of BN-based materials and potential areas for future applications in environment remediation.
Was considered a problem of an optimization of concurrent gas centrifuges for separation of Boron isotopes in form of trifluoride BF3. As the criteria was used a minimum of total number of gas ...centrifuges upon the given external parameters of the cascades' scheme. The method is based on the analytical relationships for the flows of stages, received under approximating minimization of the total feed flow. Conducted cascade calculations showed that it is possible to obtain BF3 with enrichment up to 99.9 % of 10B in the selection and up to 0.1 % in the waste, which is equivalent to 99.9 % of 11B.
•The trace angle of α laths has been defined according to orientation-trace method.•The morphology of α laths produced by 〈100〉 fiber texture has been investigated.•The transformed α laths form a ...cross configuration due to variant selection.
The microstructure morphology of transformed α is controlled by the crystallographic orientation of its parent β grain. In the fusion zone of an electron beam welded joint of TC25G titanium alloy, the columnar β grains exhibited a {001} 〈100〉 cube texture, in which four kinds of α laths with two main growth (trace line) directions formed after post-welded heat treatment. According to the numerical simulation by an orientation-trace method, the trace angle of α laths mainly distributed across the ranges of 40˚-60˚ and 120˚-140˚ in the β matrix with 〈001〉 fiber texture, thus the microstructure morphology of transformed α naturally tended to form cross configurations with two nearly perpendicular α laths.
Monodefluoroborylation of polyfluoroalkenes has been achieved in a regioselective manner under mild conditions via copper catalysis. The method has shown an extremely broad scope of substrates, ...including (difluorovinyl)arenes, tetrafluoroethylene (TFE), (trifluorovinyl)arenes, and trifluoromethylated monofluoroalkenes. The choice of boron source was important for the efficient transformation of (difluorovinyl)arenes; (Bpin)2 was suitable for substrates with an electron-deficient aryl group and (Bnep)2 for those with an electron-rich aryl group. Derivatization of the (fluoroalkenyl)boronic acid esters to the corresponding potassium trifluoroborate salts has rendered the products easily isolable, which greatly improved the synthetic practicality of the monodefluoroborylation reaction. Stoichiometric experiments indicate that the fate of the regioselectivity depends on the mode of β-fluorine elimination, which depends on the substrate. Further transformation of the boryl group has allowed facile preparation of fluoroalkene derivatives as exemplified by the synthesis of a fluoroalkene mimic of atorvastatin, which potently inhibited the enzyme activity of HMG-CoA reductase.
Heteroatom-doped carbons have drawn increasing research interest as catalysts for various electrochemical reactions due to their unique electronic and surface structures. In particular, co-doping of ...carbon with boron and nitrogen has been shown to provide significant catalytic activity for oxygen reduction reaction (ORR). However, limited experimental work has been done to systematically study these materials, and much remains to be understood about the nature of the active site(s), particularly with regards to the factors underlying the activity enhancements of these boron–carbon–nitrogen (BCN) materials. Herein, we prepare several BCN materials experimentally with a facile and controlled synthesis method, and systematically study their electrochemical performance. We demonstrate the existence of h-BN domains embedded in the graphitic structures of these materials using X-ray spectroscopy. These synthesized structures yield higher activity and selectivity toward the 2e– ORR to H2O2 than structures with individual B or N doping. We further employ density functional theory calculations to understand the role of a variety of h-BN domains within the carbon lattice for the ORR and find that the interface between h-BN domains and graphene exhibits unique catalytic behavior that can preferentially drive the production of H2O2. To the best of our knowledge, this is the first example of h-BN domains in carbon identified as a novel system for the electrochemical production of H2O2.
o‐Carborane, a cluster compound containing boron and adjacent carbon atoms, displays intriguing luminescent properties. Recently, compounds containing o‐carborane units were found to show suppressed ...aggregation‐induced quenching and intense solid‐state emission; they also show potential for the development of stimuli‐responsive luminochromic materials. In this Minireview, we introduce three kinds of fundamental photochemical properties: aggregation‐induced emission, twisted intramolecular charge transfer in crystals, and environment‐sensitive excimer formation in solids. Based on these properties, several types of luminochromism, such as thermos‐, vapo‐, and mechanochromism, have been discovered. Based mainly on results from recent studies, we illustrate these mechanisms as well as unique luminescent behaviors of o‐carborane derivatives.
Shine on you crazy diamond! In this Minireview a series of arene‐modifiedo‐carboranes are described that display solid‐state emission as well as stimuli‐responsive optical properties. The unique photochemistry of these o‐carboranes, such as aggregation‐induced emission (AIE), twist‐induced charge‐transfer (TICT) emission, and solid‐state excimer emission, is explored.
Nickel is a very abundant transition metal in the Earth’s crust, and it finds numerous applications in electrochemical processes where metallic Ni or its oxides are thermodynamically stable, ...particularly in alkaline environments. This contribution addresses electrocatalytic properties of Ni-based catalysts in reactions of fuel oxidation in alkaline media. It first details the electrochemical behavior of Ni in alkaline media and approaches to determine the active surface area of Ni electrodes. Second, the electrocatalytic activities of Ni-based electrocatalysts for the alkaline hydrogen oxidation reaction are described (an endeavor for the development of anion exchange membrane fuel cells), along with a detailed analysis of the strategies put forward to improve them. It is notably shown that the state of Ni surface (oxidized or reduced) largely determines its electrocatalytic activity. This state of the surface also conveys a pivotal importance regarding the activity of Ni for the oxidation of complex fuels (borohydride, boranes, and hydrazine). Finally, emphasis is made on the durability of Ni-based catalysts in alkaline environments. It is shown that, in such media, the material durability of Ni-based electrodes can be high, but this does not necessarily warrant stable electrocatalytic activity, because of possible deactivation following surface oxide or bulk hydride formation in operation.
•Focus on the preparation and electrochemical property of BDD film electrode.•Insight into the electrocatalytic process and mechanism on BDD electrodes towards pollutants.•The enhancement approaches ...towards electrochemical oxidation kinetics are included.•Other combination technologies based on electrochemical oxidation on BDD electrode are also described.•Perspectives and outlooks for BDD electrodes in electrochemical oxidation.
Boron-doped diamond (BDD) electrode has been considered as an optimal electrode material for electrochemical oxidation of organic contaminants in the aquatic environment due to its good physical and chemical properties. The fundamental research and practical application of BDD electrode in the mineralization of organic pollutants have been well developed up to now. In this review, the preparation and electrochemical properties of BDD film electrode are focused first. Then, we investigate the electrocatalytic process and degradation mechanisms on BDD electrodes based on the electrochemical oxidation of refractory pollutants in recent years. The enhancement approaches towards electrochemical oxidation kinetics are further highlighted, which include the establishment of high activity BDD electrodes and enhancement of mass transfer process during the electrochemical oxidation. Other combination technologies based on electrochemical oxidation with BDD electrode are also described to expand the application of BDD electrode in wastewater treatment. Further, the opportunity and prospective of BDD electrode are forecasted according to the existing problems in wastewater treatment.
A method for transition metal-free 1,2-carboboration of unactivated alkenes with bis(catecholato)diboron as the boron source in combination with alkyl halides as the alkyl component is introduced. ...The three-component reaction proceeds via a radical pathway on a broad range of unactivated alkenes, and the 1,2-carboboration products serve as valuable synthetic building blocks. Density functional theory calculations provide insights into the mechanism.
A nickel/N‐heterocyclic carbene catalytic system has been established for decarbonylative borylation of amides with B2nep2 by C−N bond activation. This transformation shows good functional‐group ...compatibility and can serve as a powerful synthetic tool for late‐stage borylation of amide groups in complex compounds. More importantly, as a key intermediate, the structure of an acyl nickel complex was first confirmed by X‐ray analysis. Furthermore, the decarbonylative process was also observed. These findings confirm the key mechanistic features of the acyl C−N bond activation process.
Keyed up: A Ni/N‐heterocyclic carbene (NHC) catalytic system has been established for the title reaction, which proceeds by C−N bond activation. As a key intermediate, the structure of an acyl nickel complex was confirmed by X‐ray analysis. The structure displays square‐planar geometry, stabilized by two NHC ligands in trans position. These findings confirm the key mechanistic features of the acyl C−N bond activation process. Boc=tert‐butoxycarbonyl, nep=neopentyl glycolato.
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