Access to Ordered Porous Molybdenum Oxycarbide/Carbon Nanocomposites

Lunkenbein, Thomas; Rosenthal, Dirk; Otremba, Torsten; Girgsdies, Frank; Li, Zihui; Sai, Hiroaki; Bojer, Carina; Auffermann, Gudrun; Wiesner, Ulrich; Breu, Josef

doi:10.1002/anie.201206183

Cited by 31 publications

(48 citation statements)

References 34 publications

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“…This value is 20 % www.zaac.wiley-vch.de ARTICLE lower than previously reported results for molybdenum oxycarbide (156 kJ·mol -1 ). [7] In addition, the oxygen content in the MoO x C y nanotubes is reduced by 65 % compared to our previous report. [7] Thus it seems likely that the lower oxygen content of the molybdenum oxycarbide nanotubes might enhance the catalytic activity.…”

Section: In Situ Carburization Of the Molybdenum Oxide Wallsmentioning

confidence: 47%

“…[7] In addition, the oxygen content in the MoO x C y nanotubes is reduced by 65 % compared to our previous report. [7] Thus it seems likely that the lower oxygen content of the molybdenum oxycarbide nanotubes might enhance the catalytic activity. However, the activation energy of the benchmark system of pure hexagonal molybdenum carbide (89 kJ·mol -1 ) is not reached.…”

Section: In Situ Carburization Of the Molybdenum Oxide Wallsmentioning

confidence: 47%

“…According to the literature [7] carburization of the molybdenum walls was achieved in argon atmosphere at 700°C for 2 h. No additional carbon source was needed. The carbon content of the P2VP brush remaining in the composite was fully sufficient.…”

Section: In Situ Carburization Of the Molybdenum Oxide Wallsmentioning

confidence: 99%

“…[6] We have previously shown that organic templates applied for mesostructuring heteropolyacids can concomitantly be used as carbon source to drive the carburization of oxidic precursors. [7] With poly(butadiene)-blockpoly(2-vinylpyridine) (PB-b-P2VP) used as template, the ratio of metal cations and the carbon content could, however, not be adjusted post formation of the hybrid material in order to meet the stoichiometry required for a quantitative carbide formation. The walls of the mesostructured transition metal carbide obtained were consequently found to be coated by a thin layer of carbon formed by pyrolysis from the excess of carbon.…”

Section: Introductionmentioning

confidence: 99%

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Selective Template Removal by Thermal Depolymerization to Obtain Mesostructured Molybdenum Oxycarbide

Schieder

Lunkenbein

Bojer

et al. 2015

Zeitschrift anorg allge chemie

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The carbon content of mesostructured organic-inorganic hybrid material of a cylindrical block copolymer template of poly(2-vinylpyridine)-block-poly(allyl methacrylate) (P2VP-b-PAMA) and ammonium paramolybdate (APM) could be reduced by thermal depolymerization. By calcination in vacuo at 320 degrees C the PAMA core can be completely removed while the remaining P2VP brush preserves the mesostructure. The P2VP-APM composite can then be carburized in-situ to MoOxCy in a second pyrolysis step without any additional carbon source but P2VP. The molybdenum oxycarbide nanotubes obtained, form hierarchically porous non-woven structures, which were tested as catalyst in the decomposition of NH3. They proved to be catalytically active at temperatures above 450 degrees C. The activation energy was estimated from an Arrhenius Plot to be 127 kJmol(-1)

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Section: In Situ Carburization Of the Molybdenum Oxide Wallsmentioning

confidence: 47%

Section: In Situ Carburization Of the Molybdenum Oxide Wallsmentioning

confidence: 47%

Section: In Situ Carburization Of the Molybdenum Oxide Wallsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Selective Template Removal by Thermal Depolymerization to Obtain Mesostructured Molybdenum Oxycarbide

Schieder

Lunkenbein

Bojer

et al. 2015

Zeitschrift anorg allge chemie

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“…The traditional synthesis method usually involves the mix of metals with carbon and subsequent carbonization under high temperature to form Mo 2 C structure, which results in serious aggregation and compromises their performance. Recently, various morphologies of Mo 2 C nanostructure with excellent HER performance have been developed through various methods [18][19][20][21][22][23]. Sun and coworkers [24] synthesized closely interconnected network of molybdenum phosphide nanostructure with highly efficient electrocatalyst for HER.…”

mentioning

confidence: 99%

Synthesis of Mo-based nanostructures from organic-inorganic hybrid with enhanced electrochemical for water splitting

Yang

Wang

2015

Sci. China Mater.

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scarcity and high cost of Pt severely hinder their practical application. Recently, various molybdenum-based compounds, such as MoS 2 , MoSe 2 , Mo 2 C, and MoP, are promising non-noble-metal candidates due to their comparable HER activity to Pt-based catalysts [15][16][17]. Among them, Mo 2 C, as a typical interstitial alloys material, has similar metallic structures and possesses Pt-like catalytic behaviors. The traditional synthesis method usually involves the mix of metals with carbon and subsequent carbonization under high temperature to form Mo 2 C structure, which results in serious aggregation and compromises their performance. Recently, various morphologies of Mo 2 C nanostructure with excellent HER performance have been developed through various methods [18][19][20][21][22][23]. Sun and coworkers [24] synthesized closely interconnected network of molybdenum phosphide nanostructure with highly efficient electrocatalyst for HER. Tang's group reported that nanoporous Mo 2 C can be obtained by thermal decomposition process under an inert atmosphere, which was used as a very effective electrocatalyst for generating hydrogen from water [25,26]. In addition, Sasaki's group demonstrated that small Mo 2 C nanoparticles loaded on carbon nanotubes showed highly active and durable electrocatalyst for HER [27]. Evidently, these results suggest that Mo 2 C can be used as an effective electrocatalyst for water splitting.Recently, the formation of MoO 2 with carbon materials such as graphene was used to further improve the performance of MoO 2 [28][29][30][31]. For example, Mai's group [32] synthesized ultrathin MoO 2 nanosheets encapsulated carbon matrix with a facile thermal reduction method, which showed high specific capacities and enhanced cycling stability. Li and co-workers [33] fabricated flawed MoO 2 nanobelts on graphene with enhanced HER performance. However, few reports focus on constructing heterocomposite Mo 2 C with MoO 2 . Compared with those of the corresponding homogeneous materials, these heterostructured A simple method to fabricate Mo-based nanostructures were developed by the thermal decomposition of MoOx-based organic-inorganic hybrid nanowires. Well-defined Mo-based nanostructures, including MoO2 and MoO3 nanowires, can be prepared by changing the hybrid precursor. More importantly, Mo2C/MoO2 heterostructures with porous structure were successfully synthesized under an inert atmosphere. The resultant Mo2C/ MoO2 heterostructures show enhanced electrocatalytic activity and superior stability for electrochemical hydrogen evolution from water. The enhanced performance might be ascribed to the high electrical conductivity and porous structures with one-dimensional structure. Indeed, our result described here provides a new way to synthesize other Mo-based nanostructures for various applications.

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A Straightforward Solvent‐Pair‐Enabled Multicomponent Coassembly Approach toward Noble‐Metal‐Nanoparticle‐Decorated Mesoporous Tungsten Oxide for Trace Ammonia Sensing

Jiang,

Deng,

Chen

et al. 2024

Advanced Materials

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The straightforward synthesis of noble‐metal‐nanoparticle‐decorated ordered mesoporous transition metal oxides remains a great challenge due to the difficulty of balancing the interactions between precursors and templates. Herein, a solvent‐pair‐enabled multicomponent coassembly (SPEMC) strategy is developed for straightforward synthesis of noble‐metal‐nanoparticle‐decorated nitrogen‐doped ordered mesoporous tungsten oxide (abbreviated as NM/N‐mWO3, NM = Pt, Rh, Pd). The amphiphilic poly(ethylene oxide)‐block‐polystyrene (PEO‐b‐PS) copolymers coassemble with ammonium metatungstate (AMT) clusters and different kinds of hydrophilic noble metal precursors without phase separation. SPEMC synthesis requires no direct interaction between PEO‐b‐PS and AMT, thus the assembly equilibriums between noble metal precursors and PEO‐b‐PS can be readily controlled. The obtained NM/N‐mWO3 nanocomposites possess ordered mesopores, abundant oxygen vacancies, and metal–metal oxide interfaces. As a result, the Pt/N‐mWO3 sensors exhibit superior ammonia sensing performances with high sensitivity, an ultralow limit of detection (51.2 ppb), good selectivity, and long‐term stability. Spectroscopic analysis reveals that ammonia is oxidized stepwise to NO, NO2−, and NO3− during the sensing process. Moreover, a portable wireless module based on Pt/N‐mWO3 sensor can recognize ppm‐level concentration of ammonia, which lays a solid foundation for its application in various fields.

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Access to Ordered Porous Molybdenum Oxycarbide/Carbon Nanocomposites

Cited by 31 publications

References 34 publications

Selective Template Removal by Thermal Depolymerization to Obtain Mesostructured Molybdenum Oxycarbide

Selective Template Removal by Thermal Depolymerization to Obtain Mesostructured Molybdenum Oxycarbide

Synthesis of Mo-based nanostructures from organic-inorganic hybrid with enhanced electrochemical for water splitting

A Straightforward Solvent‐Pair‐Enabled Multicomponent Coassembly Approach toward Noble‐Metal‐Nanoparticle‐Decorated Mesoporous Tungsten Oxide for Trace Ammonia Sensing

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