Nitrogen-Deficient ORR Active Sites Formation by Iron-Assisted Water Vapor Activation of Electrospun Carbon Nanofibers

2016 ◽  
Vol 120 (14) ◽  
pp. 7705-7714 ◽  
Author(s):  
Beomgyun Jeong ◽  
Dongyoon Shin ◽  
Myounghoon Choun ◽  
Sandip Maurya ◽  
Jaeyoon Baik ◽  
...  
Keyword(s):  
Water Vapor ◽  
Carbon Nanofibers ◽  
Active Sites

scholarly journals Green and Affordable Manufacturing Method for Multi-Scale Porous Carbon Nanofibers and Its Application in Vanadium Redox Flow Battery

2022 ◽  
Author(s):  
Dawei Fang ◽  
Xinyu An ◽  
Ang Zhang ◽  
Xi Li ◽  
Xiaoxue Ma ◽  
...  
Keyword(s):  
Water Vapor ◽  
Surface Area ◽  
Carbon Nanofibers ◽  
Porous Carbon ◽  
Active Sites ◽  
Electrode Materials ◽  
Vanadium Redox Flow Battery ◽  
Scale Production ◽  
Simple Method ◽  
Multi Scale

Abstract Carbon nanofibers with multi-scale pores have been easily constructed by synchronous water etching during the carbonization process of PAN nanofibers, reducing the additional consumption of energy and time. After etching by high-temperature water vapor, the fiber surface becomes more coarse, and large amounts of etched pits are formed, effectively increasing the electrode’s specific surface area and hydrophilicity. Oxygen content is also significantly increased, which may effectively increase the electrocatalytic active sites of the electrode. Electrochemical tests verified the improved electrocatalytic activity and increased effective surface area. As a result, the VRFB single cell with water vapor etched carbon nanofibers as its electrode shows higher battery efficiencies than that with pristine carbon nanofibers; the energy efficiency improves by nearly 9.4% at 200 mA·cm-2. After 100 charge/discharge cycles, the battery efficiency has no obvious attenuation, and the capacity attenuation rate of single cycle is nearly 0.26%，suggesting a satisfactory cycling stability. This green and simple method for constructing multi-scale porous carbon nanofibers electrode is expected to achieve large-scale production of high-performance electrode materials, and can be applied in various electrochemical energy storage systems.

Effect of Oxygen and Water in the CO Photocatalytic Oxidation with TiO2

2011 ◽  
Vol 324 ◽  
pp. 149-152
Author(s):  
Carlos Youssef ◽  
Eric Puzenat ◽  
Samir Najm ◽  
Nicole Jaffrezic-Renault ◽  
Chantal Guillard
Keyword(s):  
Water Vapor ◽  
Active Sites ◽  
Photocatalytic Oxidation ◽  
Low Oxygen ◽  
High Concentration ◽  
Co Concentration ◽  
Langmuir Hinshelwood Mechanism ◽  
Effect Of Oxygen ◽  
Two Parameters ◽  
Low Oxygen Concentration

TiO2P25 catalyst was used to study the photocatalytic oxidation of CO to CO2at 288K. Two parameters, O2and H2O were used to study its effect on the photocatalytic process. The dependency of the reaction rate on the CO concentration and water vapor was explained in terms of Langmuir-Hinshelwood mechanism. The presence of a high concentration of water vapor inhibits the CO photocatalytic oxidation at low oxygen concentration. We have noted an adsorption competition between CO and H2O on the TiO2active sites.

scholarly journals A Novel Study of Methane-Rich Gas Reforming to Syngas and Its Kinetics over Semicoke Catalyst

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Guojie Zhang ◽  
Aiting Su ◽  
Jiangwen Qu ◽  
Yannian Du
Keyword(s):  
Water Vapor ◽  
Functional Groups ◽  
Active Sites ◽  
Active Oxygen ◽  
Steam Gasification ◽  
Gas Mixture ◽  
Methane Reforming ◽  
Kinetics Study ◽  
Gasification Reaction ◽  
Reaction Processes

A small-size gasification unit is improved through process optimization to simulate industrial United Gas Improvement Company gasification. It finds that the reaction temperature has important impacts on semicoke catalyzed methane gas mixture. The addition of water vapor can enhance the catalytic activity of reforming, which is due to the fact that addition of water vapor not only removes carbon deposit produced in the reforming and gasification reaction processes, but also participates in gasification reaction with semicoke to generate some active oxygen-containing functional groups. The active oxygen-containing functional groups provide active sites for carbon dioxide reforming of methane, promoting the reforming reaction. It also finds that the addition of different proportions of methane-rich gas can yield synthesis gas with different H2/CO ratio. The kinetics study shows that the semicoke can reduce the activation energy of the reforming reaction and promote the occurrence of the reforming reaction. The kinetics model of methane reforming under the conditions of steam gasification over semicoke is as follows:k-=5.02×103·pCH40.71·pH20.26·exp(−74200/RT).

scholarly journals Active sites for the oxygen reduction reaction in nitrogen-doped carbon nanofibers

2020 ◽  
Vol 357 ◽  
pp. 248-258 ◽  
Author(s):  
Marthe E.M. Buan ◽  
Andrea Cognigni ◽  
John C. Walmsley ◽  
Navaneethan Muthuswamy ◽  
Magnus Rønning
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Carbon Nanofibers ◽  
Active Sites ◽  
Reduction Reaction ◽  
Nitrogen Doped ◽  
Nitrogen Doped Carbon

Formation of Active Sites of Carbon Nanofibers Growth in Self-Organizing Ni–Pd Catalyst during Hydrogen-Assisted Decomposition of 1,2-Dichloroethane

2018 ◽  
Vol 58 (2) ◽  
pp. 685-694 ◽  
Author(s):  
Yurii I. Bauman ◽  
Ilya V. Mishakov ◽  
Yulia V. Rudneva ◽  
Pavel E. Plyusnin ◽  
Yury V. Shubin ◽  
...  
Keyword(s):  
Carbon Nanofibers ◽  
Active Sites ◽  
Pd Catalyst ◽  
Assisted Decomposition ◽  
Self Organizing

scholarly journals Preparation of a Composite Material AC/Cu-BTC with Improved Water Stability and n-Hexane Vapor Adsorption

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Manlin Li ◽  
Weiqiu Huang ◽  
Bo Tang ◽  
Fujiao Song ◽  
Aihua Lv ◽  
...  
Keyword(s):  
Composite Material ◽  
Water Vapor ◽  
Active Sites ◽  
Water Vapor Adsorption ◽  
Water Molecules ◽  
Water Stability ◽  
Ambient Conditions ◽  
Hexane Vapor ◽  
Vapor Adsorption ◽  
Organic Linker

The Cu-BTC, a widely studied metal-organic framework (MOF), has been applied in various fields such as gas adsorption, separation, storage, and catalysis. However, the Cu-BTC collapses due to the replacement of the organic linker by water molecules under humid conditions, which limits its practical application in industries. In consideration of the undesirable water effect on the framework stability of Cu-BTC, a stable activated carbon (AC) was incorporated into it by the in situ method to yield a composite material AC/Cu-BTC with high water stability. XRD and SEM patterns proved that the AC7%/Cu-BTC successfully retains its crystal structure after being exposed to water molecules. The adsorption amount of n-hexane vapor of the AC7%/Cu-BTC after water vapor adsorption-thermal desorption is 307% of that of the Cu-BTC. The addition of the AC changes the adsorption active sites and reduces the strong affinity of the Cu-BTC to water molecules, resulting in the AC7%/Cu-BTC having a much lower adsorption rate for water vapor than the Cu-BTC. Therefore, the AC7%/Cu-BTC can be protected from a large amount of water molecules and avoid structural collapse caused by the disconnection between the copper center and the organic linker. The composite displays a potential value for stable applications of MOF-based materials under ambient conditions.

scholarly journals Evaluation of ORR active sites in nitrogen-doped carbon nanofibers by KOH post treatment

2018 ◽  
Vol 301 ◽  
pp. 11-16 ◽  
Author(s):  
Navaneethan Muthuswamy ◽  
Marthe E.M. Buan ◽  
John C. Walmsley ◽  
Magnus Rønning
Keyword(s):  
Carbon Nanofibers ◽  
Active Sites ◽  
Post Treatment ◽  
Nitrogen Doped ◽  
Nitrogen Doped Carbon

scholarly journals Characterization of Carbon Nanofibers Treated with Thermal Nitrogen as a Catalyst Support Using Point-of-Zero Charge Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Thien Duc Nguyen Van ◽  
Suriati Sufian ◽  
Nurlidia Mansor ◽  
Noorhana Yahya
Keyword(s):  
Carbon Nanofibers ◽  
Amorphous Carbon ◽  
Active Sites ◽  
Gas Flow ◽  
Carbon Nanofiber ◽  
Catalyst Support ◽  
Carbon Surface ◽  
Point Of Zero Charge ◽  
Zero Charge ◽  
Defect Sites

The chemical and physical purification of carbon nanofiber exposes more anchoring sites between meal precursors and carbon surface but thermal N2gas flow maintains the crystal’s structure as well as its defect and edge sites, referred to as active sites or anchoring sites. After calcination in nitrogen at 450°C, samples were characterized by Raman spectra X-ray diffraction, as well as thermogravimetric and nitrogen physisorption analyses. Results showed a relatively lower fraction of amorphous carbon to graphite, indicating a greater removal of amorphous carbon. Moreover, the disorder intensity of carbon nanofibers that were treated in N2flow rate of 1 L/min and 3 hours, called 1Gcom-3h sample, achieved far more defect sites compared with unmodified carbon nanofiber. In addition, the surface areas of mesoporous carbon nanofibers decreased over prolonged residence time. The carbon nanofiber support-metal cation interaction therefore improved the deposition of iron when the point-of-zero charge reading was greater than four.

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