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In situ oxidation of carbon-encapsulated cobalt nanocapsules creates highly active cobalt oxide catalysts for hydrocarbon combustion.

Wang H, Chen C, Zhang Y, Peng L, Ma S, Yang T, Guo H, Zhang Z, Su DS, Zhang J - Nat Commun (2015)

Bottom Line: Combustion catalysts have been extensively explored to reduce the emission of hydrocarbons that are capable of triggering photochemical smog and greenhouse effect.Palladium as the most active material is widely applied in exhaust catalytic converter and combustion units, but its high capital cost stimulates the tremendous research on non-noble metal candidates.For methane combustion, the catalyst displays a unique activity being comparable or even superior to the palladium ones.

View Article: PubMed Central - PubMed

Affiliation: Shenyang National Laboratory for Material Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.

ABSTRACT
Combustion catalysts have been extensively explored to reduce the emission of hydrocarbons that are capable of triggering photochemical smog and greenhouse effect. Palladium as the most active material is widely applied in exhaust catalytic converter and combustion units, but its high capital cost stimulates the tremendous research on non-noble metal candidates. Here we fabricate highly defective cobalt oxide nanocrystals via a controllable oxidation of carbon-encapsulated cobalt nanoparticles. Strain gradients induced in the nanoconfined carbon shell result in the formation of a large number of active sites featuring a considerable catalytic activity for the combustion of a variety of hydrocarbons (methane, propane and substituted benzenes). For methane combustion, the catalyst displays a unique activity being comparable or even superior to the palladium ones.

No MeSH data available.


Related in: MedlinePlus

Scheme for the transformation process of the Co3O4 catalyst.The attenuation of carbon shells in oxygen-containing reaction condition allows the inward diffusion of oxygen and the oxidation of subjacent metallic Co atoms gradually. The volumetric expansion due to phase transformation gives rise to a large strain force to induce the disintegration of bulk oxides. The Co3O4 nanocrystals were finally formed with nanoscale interconnecting pores at elevated temperatures.
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f4: Scheme for the transformation process of the Co3O4 catalyst.The attenuation of carbon shells in oxygen-containing reaction condition allows the inward diffusion of oxygen and the oxidation of subjacent metallic Co atoms gradually. The volumetric expansion due to phase transformation gives rise to a large strain force to induce the disintegration of bulk oxides. The Co3O4 nanocrystals were finally formed with nanoscale interconnecting pores at elevated temperatures.

Mentions: We have demonstrated here the highly active and durable Co3O4 nanocrystals deriving from Co@C nanocapsules, which efficiently catalysed the combustion of various hydrocarbons especially CH4. The formation process of Co3O4 nanocrystals is illustrated in Fig. 4. The attacks of oxygen result in the partial combustion of carbon shells and consequently the oxidation of subjacent metallic Co atoms, raising Co oxides islands due to the inward diffusion of oxygen. Meanwhile, the immediate volumetric expansion inside the residual carbon shells gives rise to a large strain force to induce the disintegration of bulk oxides. Finally, at elevated temperatures, the oxides nanocrystals with an enlarged particle size and nanoscale interconnecting pores were formed after the complete burning of carbon shells. The defective surface comprising mostly high-index facets endows a considerable activity for combustion of alkanes, and the deviously interconnecting channels allow an efficient mass transfer of reactants. Provided more efforts were made to optimize the structural parameters of nanocapsules, this strategy can be used to synthesize a variety of oxides catalysts for applications in more catalysis processes.


In situ oxidation of carbon-encapsulated cobalt nanocapsules creates highly active cobalt oxide catalysts for hydrocarbon combustion.

Wang H, Chen C, Zhang Y, Peng L, Ma S, Yang T, Guo H, Zhang Z, Su DS, Zhang J - Nat Commun (2015)

Scheme for the transformation process of the Co3O4 catalyst.The attenuation of carbon shells in oxygen-containing reaction condition allows the inward diffusion of oxygen and the oxidation of subjacent metallic Co atoms gradually. The volumetric expansion due to phase transformation gives rise to a large strain force to induce the disintegration of bulk oxides. The Co3O4 nanocrystals were finally formed with nanoscale interconnecting pores at elevated temperatures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490405&req=5

f4: Scheme for the transformation process of the Co3O4 catalyst.The attenuation of carbon shells in oxygen-containing reaction condition allows the inward diffusion of oxygen and the oxidation of subjacent metallic Co atoms gradually. The volumetric expansion due to phase transformation gives rise to a large strain force to induce the disintegration of bulk oxides. The Co3O4 nanocrystals were finally formed with nanoscale interconnecting pores at elevated temperatures.
Mentions: We have demonstrated here the highly active and durable Co3O4 nanocrystals deriving from Co@C nanocapsules, which efficiently catalysed the combustion of various hydrocarbons especially CH4. The formation process of Co3O4 nanocrystals is illustrated in Fig. 4. The attacks of oxygen result in the partial combustion of carbon shells and consequently the oxidation of subjacent metallic Co atoms, raising Co oxides islands due to the inward diffusion of oxygen. Meanwhile, the immediate volumetric expansion inside the residual carbon shells gives rise to a large strain force to induce the disintegration of bulk oxides. Finally, at elevated temperatures, the oxides nanocrystals with an enlarged particle size and nanoscale interconnecting pores were formed after the complete burning of carbon shells. The defective surface comprising mostly high-index facets endows a considerable activity for combustion of alkanes, and the deviously interconnecting channels allow an efficient mass transfer of reactants. Provided more efforts were made to optimize the structural parameters of nanocapsules, this strategy can be used to synthesize a variety of oxides catalysts for applications in more catalysis processes.

Bottom Line: Combustion catalysts have been extensively explored to reduce the emission of hydrocarbons that are capable of triggering photochemical smog and greenhouse effect.Palladium as the most active material is widely applied in exhaust catalytic converter and combustion units, but its high capital cost stimulates the tremendous research on non-noble metal candidates.For methane combustion, the catalyst displays a unique activity being comparable or even superior to the palladium ones.

View Article: PubMed Central - PubMed

Affiliation: Shenyang National Laboratory for Material Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.

ABSTRACT
Combustion catalysts have been extensively explored to reduce the emission of hydrocarbons that are capable of triggering photochemical smog and greenhouse effect. Palladium as the most active material is widely applied in exhaust catalytic converter and combustion units, but its high capital cost stimulates the tremendous research on non-noble metal candidates. Here we fabricate highly defective cobalt oxide nanocrystals via a controllable oxidation of carbon-encapsulated cobalt nanoparticles. Strain gradients induced in the nanoconfined carbon shell result in the formation of a large number of active sites featuring a considerable catalytic activity for the combustion of a variety of hydrocarbons (methane, propane and substituted benzenes). For methane combustion, the catalyst displays a unique activity being comparable or even superior to the palladium ones.

No MeSH data available.


Related in: MedlinePlus