Formation of encapsulated molybdenum carbide particles by annealing mechanically activated mixtures of amorphous carbon with molybdenum

Bokhonov, Boris B.; Borisova, Yu. A.; Корчагин, М. А.

doi:10.1016/j.carbon.2004.04.016

Cited by 25 publications

(9 citation statements)

References 23 publications

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“…The similar data were obtained for systems Fe-C, 473 Zr-C, 474 Ti-C, 475 TiH 2 -C, 476 Mg-C, 477 Mo-C, 478 Si-C, 479 Al-BN and Mg-BN, 480 Ti-BN 480,481 and Fe-BN. 482 General mechanisms are identical for all systems.…”

Section: Metal-ceramic Nanocompositesmentioning

confidence: 99%

Hallmarks of mechanochemistry: from nanoparticles to technology

et al. 2013

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The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).

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Section: Metal-ceramic Nanocompositesmentioning

confidence: 99%

Hallmarks of mechanochemistry: from nanoparticles to technology

et al. 2013

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“…Carbon sources in solid form, such as MWCNTs [3,31,33] and in liquid form, such as urea [3,35], have been also used in the preparation of carbide species. Chemical vapor deposition, the microwave-assisted method, arc melting, and mechanical activation are some examples for other methods for the preparation of molybdenum carbide and it was found that properties of carbide species, such as crystal structure, particle size, morphology, and surface area were affected by the synthesis procedure as well as carbon source [3,37]. Yang et al reported a route that included a reaction between anhydrous molybdenum chloride with graphite or CNTs in metallic Na medium at 500°C to synthesize nanocrystalline Mo 2 C [31].…”

Section: Resultsmentioning

confidence: 99%

Multiwall carbon nanotube-supported molybdenum catalysts for ammonia decomposition reaction under microwave effect

Guler

Varışlı

2020

Turk J Chem

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In this study, microwave-assisted ammonia decomposition reaction was investigated over molybdenum incorporated catalysts. Due to the selective, volumetric, and noncontact heating properties of the microwave system, higher conversion values could be achieved at relatively lower reaction temperatures, which is important for on-site COx-free hydrogen production. Multiwall carbon nanotube-supported molybdenum catalysts were prepared following the impregnation procedure with different metal loading (3.5%–12.5% wt%), and inductively coupled plasma, nitrogen physisorption, X-ray diffraction, and transmission electron microscopic techniques were employed to characterize the fresh and used samples. Reaction experiments were performed under the flow of pure ammonia with a gas hourly space velocity of 36,000 mL/g cat. h for both the microwave and conventionally heated reaction systems. It was found that ammonia conversion was obtained even at 400 °C, reaching 40%, and total conversion was observed even at 450 °C, while the activities of these catalysts were negligible at a reaction temperature lower than 550 °C, in the conventional heated system, which included an electrically heated furnace. Crystals of α-Mo 2 C as well as MoO 2 were observed in the structures of the synthesized catalysts and the formation of nitride species was more easily observable under microwave heating, possibly due to the nitridation of molybdenum carbide species during the reaction.

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“…Compared to the reaction between MoO 3 and sucrose, the reaction between MoO 3 and carbon film occurs at much higher temperature, indicating the higher activation energy of the reaction. It has been demonstrated that the relative stable amorphous carbon produces hcp Mo 2 C while the activated carbon with high reactivity leads to the formation of fcc MoC . The relative inert carbon precursor from carbon film gives rise to low reduction atmosphere and makes carbon atoms difficult to occupy interstitial sites, which consequently leads to the formation of Mo 2 C. With the use of sucrose source, the carbon precursor has a high portion of sp 3 hybridization and crosslinked carbon atoms with high reactivity.…”

Section: Resultsmentioning

confidence: 99%

Phase and Facet Control of Molybdenum Carbide Nanosheet Observed by In Situ TEM

Lin

Cai

Lü

et al. 2017

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Transition metal carbides are of great potential for electrochemical applications. The phase and facet of molybdenum carbides greatly affect the electrochemical performance. Carburization of MoO3 inside a transmission electron microscope to monitor the growth process of molybdenum carbides is performed. Carbon sources with different activities are used and the controllable growth of molybdenum carbides is investigated. The results show that the relatively inert amorphous carbon film produces Mo2C, where the interstitial sites formed by hexagonal closed packing molybdenum atoms are partially occupied by carbon atoms. In contrast, the carbon decomposed from the sucrose has a high portion of sp3 hybridized and crosslinked carbon atoms with high reactivity, leading to the formation of MoC with full occupation of interstitial sites by carbon atoms. In addition, the MoC growth experiences a (111) to (100) facets change with the increase of temperature. The (111) facet formed at low temperature has Mo‐terminated or C‐terminated surface with higher surface energy and higher reactivity, while the (100) facet with 1:1 C/Mo ratio on the surface exhibits enhanced stability. The phase and facet control by carbon source and temperature allow us to tune the crystal structures and surface atoms as well as their electrochemical properties.

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Formation of encapsulated molybdenum carbide particles by annealing mechanically activated mixtures of amorphous carbon with molybdenum

Cited by 25 publications

References 23 publications

Hallmarks of mechanochemistry: from nanoparticles to technology

Hallmarks of mechanochemistry: from nanoparticles to technology

Multiwall carbon nanotube-supported molybdenum catalysts for ammonia decomposition reaction under microwave effect

Phase and Facet Control of Molybdenum Carbide Nanosheet Observed by In Situ TEM

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