Single-step Synthesis of Molybdenum Carbide Nanoparticles by Wire Explosion Process
TL;DR: In this paper, the synthesis of MoC 1-x nanoparticles (NPs) with Mo wire as starting material and to carryout explosion in the methane gas medium, which acts as carburizing medium, as well as a coolant, to bring down the local temperature rise to a value lower than the melting point of the material.
Abstract: We propose the synthesis of MoC 1-x nanoparticles (NPs) with Mo wire as starting material and to carryout explosion in the methane gas medium, which acts as carburizing medium, as well as a coolant, to bring down the local temperature rise to a value lower than the melting point of the material. To control the phase and morphology of NPs, two parameters are defined in wire explosion process (WEP): energy ratio, K (ratio of energy supplied to wire and sublimation energy of wire) and pressure, P of ambient gas. XRD, TEM, SEM and XPS were used to characterize the synthesized NPs. Pure Moc 1-x was synthesized for K = 5.8 and P = 170 kPa. Carburization is more for high K/P. For low pressure case, one has to provide more K to get complete carburization. XPS confirms the formation of MoC without any oxidation of Mo vapour. Spherical NPs were obtained with least mean particle size of 20 nm. Particle size decreases with increase in K and/or decrease in P.
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TL;DR: In this article, four phases of molybdenum carbide were synthesized and investigated for their electrocatalytic activity and stability for hydrogen evolution reaction in acidic solution.
Abstract: Molybdenum carbide has been proposed as a possible alternative to platinum for catalyzing the hydrogen evolution reaction (HER). Previous studies were limited to only one phase, β-Mo2C with an Fe2N structure. Here, four phases of Mo-C were synthesized and investigated for their electrocatalytic activity and stability for HER in acidic solution. All four phases were synthesized from a unique amine-metal oxide composite material including γ-MoC with a WC type structure which was stabilized for the first time as a phase pure nanomaterial. X-ray photoelectron spectroscopy (XPS) and valence band studies were also used for the first time on γ-MoC. γ-MoC exhibits the second highest HER activity among all four phases of molybdenum carbide, and is exceedingly stable in acidic solution.
746 citations
"Single-step Synthesis of Molybdenum..." refers background in this paper
...Different phases of molybdenum carbide (MoC) is researched due to its application in many industrial problems especially in hydrogen evolution reaction [1,2]....
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TL;DR: In this article, the development of the method of electric explosion of wires and research results concerning preparation of nanopowders by this method has been reviewed and several characteristics of the nanopowsders were given and their applications were exemplified too.
Abstract: The development of the method of electric explosion of wires and research results concerning preparation of nanopowders by this method has been reviewed. The method is highly productive (up to 200g/h), provides powders with an average particle size of 20–100nm, and requires an energy consumption of about 25kWh/kg. Several characteristics of the nanopowders will be given and their applications will be exemplified too.
368 citations
"Single-step Synthesis of Molybdenum..." refers background or methods in this paper
...Wire explosion process (WEP) offers single step synthesis method of NPs with least number (two) of precursors [12-17]....
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...In one setup, one can form metal [12], its oxide [15], carbide [16], alloy [17] and other composite NPs by exploding the suitable wire in appropriate ambient....
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TL;DR: The complete ethanolysis of Kraft lignin over an α-MoC1-x /AC catalyst in pure ethanol at 280 °C to give high-value chemicals of low molecular weight with a maximum overall yield of the 25 most abundant liquid products (LP25) of 1.64 g per gram of lignIn.
Abstract: We report the complete ethanolysis of Kraft lignin over an α-MoC1−x/AC catalyst in pure ethanol at 280 °C to give high-value chemicals of low molecular weight with a maximum overall yield of the 25 most abundant liquid products (LP25) of 1.64 g per gram of lignin. The LP25 products consisted of C6–C10 esters, alcohols, arenes, phenols, and benzyl alcohols with an overall heating value of 36.5 MJ kg−1. C6 alcohols and C8 esters predominated and accounted for 82 wt % of the LP25 products. No oligomers or char were formed in the process. With our catalyst, ethanol is the only effective solvent for the reaction. Supercritical ethanol on its own degrades Kraft lignin into a mixture of small molecules and molecular fragments of intermediate size with molecular weights in the range 700–1400, differing in steps of 58 units, which is the weight of the branched-chain linkage C3H6O in lignin. Hydrogen was found to have a negative effect on the formation of the low-molecular-weight products.
290 citations
"Single-step Synthesis of Molybdenum..." refers background in this paper
...Its distinct traits are harnessed for carbon monoxide hydrogenation [3], electrode of electrochemical capacitor [4], for the conversion of vegetable oils [5], catalytic ethanolysis [6] also....
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TL;DR: Nanostructure engineering on the design and preparation of highly efficient electrocatalysts based on Mox C is presented, followed by the comparison and discussion of HER performance on M ox C-based electrocatalyststs.
Abstract: Electrocatalytic water splitting is a promising approach for clean and sustainable hydrogen production. Its large-scale application relies on the availability of low cost and efficient electrocatalysts. Earth-abundant transition-metal carbides, especially molybdenum carbides (Mox C), are regarded as potential candidates to replace state-of-art but expensive platinum-group electrocatalysts. In this Review, we summarize recent progress in Mox C electrocatalysts for hydrogen evolution reaction (HER). Nanostructure engineering on the design and preparation of highly efficient electrocatalysts based on Mox C is presented, followed by the comparison and discussion of HER performance on Mox C-based electrocatalysts. Finally, we offer a perspective on the future development of Mox C-based electrocatalysts towards HER.
255 citations
"Single-step Synthesis of Molybdenum..." refers background in this paper
...Different phases of molybdenum carbide (MoC) is researched due to its application in many industrial problems especially in hydrogen evolution reaction [1,2]....
[...]
TL;DR: In this paper, the peak current of /spl sim/10 kA, the pulse length of 20 /spl mu/s, and the pulse energy of 80 J were achieved for a typical powder production rate of 5 mg/pulse, with the results of surface area measurement have given the average powder sizes in the range of 20/spl sim /70 nm, depending on the material of the powder.
Abstract: The pulsed wire discharge, as one of the well-developed pulsed power technologies, has been successfully applied to nanosize powder production. In the demonstration experiments, the discharge was carried out with the peak current of /spl sim/10 kA, the pulse length of /spl sim/20 /spl mu/s, and the pulse energy of /spl sim/80 J. Nanosize powders of metals (Al, Fe, Cu, Mo, and Pb), metal oxides (Al/sub 2/O/sub 3/, TiO/sub 2/, Fe/sub 2/O/sub 3/, NiO, ZrO/sub 2/, SnO/sub 2/, and PbO), and metal nitrides (TiN, ZrN, Ta/sub 2/N) have been synthesized by pulsed discharge of metal wires in argon, oxygen, or nitrogen. The typical powder production rate was /spl sim/5 mg/pulse. The results of surface-area measurement have given the average powder sizes in the range of 20/spl sim/70 nm, depending on the material of the powder.
183 citations
"Single-step Synthesis of Molybdenum..." refers methods in this paper
...Wire explosion process (WEP) offers single step synthesis method of NPs with least number (two) of precursors [12-17]....
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