BCN network-encapsulated multiple phases of molybdenum carbide for efficient hydrogen evolution reactions in acidic and alkaline media

Anjum, Mohsin Ali Raza; Lee, Min Hee; Lee, Jae Sung

doi:10.1039/c7ta03407e

Cited by 83 publications

(61 citation statements)

References 39 publications

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“…The XRD pattern of MoC x /Ni‐650 calcined at 650 °C exhibits its well‐crystallized feature, and the reflections located at 34.48°, 38.08°, 39.48°, 52.18°, 61.58° can be readily indexed to the (100), (002), (101), (102), (110) planes of ß‐Mo 2 C (PDF#35–0787), respectively. The two particular peaks at around 36.88° and 42.68° are ascribed to η‐MoC (PDF#08–0384, labeled with *) . We noticed that the diffraction peaks of η‐MoC became diminished for MoC x /Ni‐750, implying the phase transition from η‐MoC to ß‐Mo 2 C, in accordance with He's report .…”

Section: Resultssupporting

confidence: 87%

Ni‐Assisted Low Temperature Synthesis of MoC_x with Enhanced HER Activity

Zhou

Huang

Zhang

et al. 2017

Chemistry A European J

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Here we report a novel one-pot approach to synthesize MoC catalysts at much lowered temperature for hydrogen evolution reaction (HER) in acidic solution. A room-temperature co-precipitation reaction among Ni , MoO and 2-methylimidazole in an aqueous solution produced a Mo-Ni-imidazole complex, which was used as the precursor to fabricate MoC . The morphological and chemical properties of the obtained MoC affected by calcination and other additive metal sources (like Fe, Co, Cu) were investigated in detail. We demonstrated that Ni-Mo alloying took place prior to MoC formation during heating, which catalyzed the crystallization of MoC at relatively low temperature. The MoC /Ni-650 catalyst exhibited a quite low overpotential of 172 mV at 20 mA cm . The high performance originates from the synergistic effect between MoC and Ni-Mo alloy, high ratio of Mo /Mo , as well as high electrochemically active surface area and low charge-transfer resistance. This work would open a new way to the design and fabrication of other transition-metal carbide catalysts.

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Section: Resultssupporting

confidence: 87%

Ni‐Assisted Low Temperature Synthesis of MoC_x with Enhanced HER Activity

Zhou

Huang

Zhang

et al. 2017

Chemistry A European J

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“…[19] Moreover,t he metastable a-MoC 1Àx coulda lso be fabricated by direct pyrolysis of Mo-containing organic-inorganic hybridsa t al ow temperaturei na ni nert atmosphere and it would transform into b-Mo 2 Ca tahigh temperature (commonlym ore than 800 8C) via the re-arrangement of Mo atoms, which is always incompletable but inevitable. [20][21][22] Actually,f or both preparation progress, the phase transformation from a-MoC 1Àx to b-Mo 2 Ci sd ue to the migration andr e-arrangemento fM oa toms upon increased temperature. If the phase transformation could be suppressedb yr estricting the displacemento fM oa toms continuously upon increased temperature, high-temperature stabilized metastable a-MoC 1Àx may be achieved.…”

Section: Introductionmentioning

confidence: 99%

Achieving High‐Temperature Stability of Metastable α‐MoC_1‐x by Suppressing Phase Transformation with Mounted Atoms for Lithium Storage Performance

Gao

Meng

Yang

et al. 2019

Chemistry An Asian Journal

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Despite as ignificant advancement in preparing metastable materials, one common problem is the strict and precious reaction conditions due to their metastable structures. Herein, we achieved the preparationo fh igh-temperature stabilized metastable a-MoC 1Àx by mounting zinc atoms into its lattice structure. Such as tructural construction could suppress the phase transformation from a-MoC 1Àx to b-Mo 2 C through restricting the displacement of Mo atoms upon increased temperature. The resultant metastable a-MoC 1Àx can be stabilized up to 1000 8Ca nd this stabilityt emperature is the highest for the metastable a-MoC 1Àx so far.S ynchrotron X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) confirm the structure of Zn-mount-ed a-MoC 1Àx .D ensityf unctional theory (DFT)c alculations revealt hat the introductiono ft he Zn atoms in the lattice structure of a-MoC 1Àx could significantly decrease the energy difference( DE)b etween a-MoC 1Àx and b-Mo 2 C, thus effectively suppressing the phase transformation from a-MoC 1Àx to b-Mo 2 Ca nd accordingly maintaining the hightemperature stability of a-MoC 1Àx .T his novel strategy can be used as au niversal methodt ob ee xtended to synthesize metastable a-MoC 1Àx from different precursors or other mounted elements. Moreover, the optimal product exhibits excellent lithium storage performances in terms of the cycling stability and rate performance. [c] P. Yang Chinese Academy of Engineering Physics Mianyang 621900 (P.R .China) Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Scheme1.The schematicillustration of the fabrication procedureofc ubic a-MoC 1Àx with high-temperature stability( yellow,black, and red balls, represent Mo, C, and Zn atoms, respectively).

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“…35‐0787) and β‐Mo 2 C (JCPDS no. 03‐065‐8364), respectively. The broad peak at 25° was assigned to carbon.…”

Section: Resultsmentioning

confidence: 98%

Polyoxometalate and Resin‐Derived P‐Doped Mo₂C@N‐Doped Carbon as a Highly Efficient Hydrogen‐Evolution Reaction Catalyst at All pH Values

Yan

Feng

Khan

et al. 2017

Chemistry An Asian Journal

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A new type of P-doped Mo C coated by N-doped carbon (P-Mo C@NC) has been successfully prepared by calcining a mixture of H [PMo O ] polyoxometalates (POMs) and urea-formaldehyde resin under an N atmosphere. Urea-formaldehyde resin not only serves as the carbon source to ensure carbonization but also facilitates the uniform distribution of POM precursors, which efficiently avoid the aggregation of Mo C particles at high temperatures. TEM analysis revealed that the average diameter of the Mo C particles was about 10 nm, which is coated by a few-layer N-doped carbon sheet. The as-prepared P-Mo C@NC displayed excellent hydrogen-evolution reaction (HER) performance and long-term stability in all pH environments. To reach a current density of 10 mA cm , only 109, 159, and 83 mV were needed for P-Mo C@NC in 0.5 m H SO (pH 0), 0.1 m phosphate buffer (pH 7), and 1 m KOH (pH 14), respectively. This could provide a high-yield and low-cost method to prepare uniform nanosized molybdenum carbides with highly efficient and stable HER performance.

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BCN network-encapsulated multiple phases of molybdenum carbide for efficient hydrogen evolution reactions in acidic and alkaline media

Abstract: Five phases of molybdenum carbide encapsulated by a boron–carbon–nitrogen (BCN) network are synthesized by decomposition of a Mo–imidazole-borate organometallic complex with slight variations in the imidazole-borate ligand structure.

Cited by 83 publications

References 39 publications

Ni‐Assisted Low Temperature Synthesis of MoC_x with Enhanced HER Activity

Ni‐Assisted Low Temperature Synthesis of MoC_x with Enhanced HER Activity

Achieving High‐Temperature Stability of Metastable α‐MoC_1‐x by Suppressing Phase Transformation with Mounted Atoms for Lithium Storage Performance

Polyoxometalate and Resin‐Derived P‐Doped Mo₂C@N‐Doped Carbon as a Highly Efficient Hydrogen‐Evolution Reaction Catalyst at All pH Values

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BCN network-encapsulated multiple phases of molybdenum carbide for efficient hydrogen evolution reactions in acidic and alkaline media

Abstract: Five phases of molybdenum carbide encapsulated by a boron–carbon–nitrogen (BCN) network are synthesized by decomposition of a Mo–imidazole-borate organometallic complex with slight variations in the imidazole-borate ligand structure.

Cited by 83 publications

References 39 publications

Ni‐Assisted Low Temperature Synthesis of MoCx with Enhanced HER Activity

Ni‐Assisted Low Temperature Synthesis of MoCx with Enhanced HER Activity

Achieving High‐Temperature Stability of Metastable α‐MoC1‐x by Suppressing Phase Transformation with Mounted Atoms for Lithium Storage Performance

Polyoxometalate and Resin‐Derived P‐Doped Mo2C@N‐Doped Carbon as a Highly Efficient Hydrogen‐Evolution Reaction Catalyst at All pH Values

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Ni‐Assisted Low Temperature Synthesis of MoC_x with Enhanced HER Activity

Ni‐Assisted Low Temperature Synthesis of MoC_x with Enhanced HER Activity

Achieving High‐Temperature Stability of Metastable α‐MoC_1‐x by Suppressing Phase Transformation with Mounted Atoms for Lithium Storage Performance

Polyoxometalate and Resin‐Derived P‐Doped Mo₂C@N‐Doped Carbon as a Highly Efficient Hydrogen‐Evolution Reaction Catalyst at All pH Values