The formation of nitrogen-containing functional groups on carbon nanotube surfaces: a quantitative XPS and TPD study

Kundu, Shankhamala; Xia, Wei; Busser, Wilma; Becker, Marc; Schmidt, Diedrich A.; Havenith, Martina; Mühler, Martin

doi:10.1039/b923651a

Cited by 330 publications

(269 citation statements)

References 42 publications

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“…The broad peak at 399.8 eV (see Figure 1) is consistent with the presence of imides/lactams/amides; 33 while it is not possible by XPS to distinguish between the different groups. 34 The pristine Vulcan XC72 carbon was also subjected to the same analysis and, as expected, no N-containing surface groups could be detected ( Figure 1). …”

Section: Resultsmentioning

confidence: 99%

The Key to High Performance Low Pt Loaded Electrodes

Orfanidi

Madkikar

El‐Sayed

et al. 2017

J. Electrochem. Soc.

193

246

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The effect of ionomer distribution on the oxygen mass transport resistance, the proton resistivity of the cathode catalyst layer, and the H 2 /air fuel cell performance was investigated for catalysts with surface modified carbon supports. By introducing nitrogen containing surface groups, it was shown that the ionomer distribution in the cathodic electrode can be optimized to decrease mass transport related voltage losses at high current density. The in house prepared catalysts were fully characterized by TEM, TGA, elemental analysis, and XPS. Thin-film rotating disk electrode measurements showed that the carbon support modification did not affect the oxygen reduction activity of the catalysts, but exclusively affects the ionomer distribution in the electrode during electrode preparation. Limiting current measurements were used to determine the pressure independent oxygen transport resistance -primarily attributed to oxygen transport in the ionomer film -which decreases for catalysts with surface modified carbon support. Systematically lowering the ionomer to carbon ratio (I/C) from 0.65 to 0.25 revealed a maximum performance at I/C = 0.4, where an optimum between ionomer thickness and proton conductivity within the catalyst layer is obtained. From this work, it can be concluded that not only ionomer film thickness, but more importantly ionomer distribution is the key to high performance low Pt loaded electrodes.

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Section: Resultsmentioning

confidence: 99%

The Key to High Performance Low Pt Loaded Electrodes

Orfanidi

Madkikar

El‐Sayed

et al. 2017

J. Electrochem. Soc.

193

246

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show abstract

“…The treatment carried out with urea induces the formation of cyano or amino groups (representing 0.88%), an increase of N5 groups (0.52%) and the disappearance of the -NO 2 and N-Q groups. Since cyano and amine groups are thermally decomposed, the final thermal treatment eliminates these species, suggesting that some N5 groups are converted to N6 groups (0.36%) [40,41].…”

Section: Characterization Of Original and Treated Mwcntsmentioning

confidence: 99%

Catalytic activity and stability of multiwalled carbon nanotubes in catalytic wet air oxidation of oxalic acid: The role of the basic nature induced by the surface chemistry

Rocha

Sousa

Silva

et al. 2011

Applied Catalysis B: Environmental

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“…5,16,18 The peak at 401.5-403.1 eV, can be attributed to the quaternary or graphitic-like nitrogen, which are the highly coordinated nitrogen atoms substituting carbon atoms on the graphene layers and bonded each to three carbon atoms. [36][37][38] The peak that appears at 404.7-405.7 eV can be attributed to nitrogen in the form of nitrogen oxides of pyridinic nitrogen exhibiting similar bonding with oxygen chemisorbed on the nitrogen atom. 2,12,14 The presence of oxygen on the samples was originated from a cleaning treatment with HNO 3 to remove impurities; carbon chemical oxidation generated therefore oxygen-containing groups on the carbon surface, as quinone groups.…”

Section: Synthesized N-cnts At Different Temperatures (750-950mentioning

confidence: 99%

Influence of the Synthesis Parameters in Carbon Nanotubes Doped with Nitrogen for Oxygen Electroreduction

González

Valenzuela-Muñiz

Alonso-Núñez

et al. 2017

ECS J. Solid State Sci. Technol.

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Nitrogen doped carbon nanotubes (N-CNTs) were synthesized by modified chemical vapor deposition method using a novel two steps thermal technique. Pyridine was used as carbon and nitrogen source and ferrocene as catalyst for nanotubes growth. The effects of reactor temperature and carrier gas flow were investigated using scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and linear scan voltammetry. Results show that the synthesis temperature and gas flow rate have influence on the physical, chemical and electrochemical properties of the nanostructures. Microscopy studies exhibit that synthesis temperature modify the length, yield and diameter of the N-CNTs. Transmission microscopy electron images show multiwalled carbon nanotubes with the typical bamboo like structures. High temperature and low flow rate generate more defects, as revealed by Raman analyses. N-CNTs synthesized at the highest temperature and flow rate show better electrocatalytic activity toward oxygen reduction reaction with promising lower onset potential and current densities up to 80% when compared to traditional Pt/C. The favorable performance is attributed to the higher nitrogen content and the type of nitrogen species, mainly pyrrolic and pyridinic incorporated in the carbon lattice. For the last decades, platinum (pure and Pt alloys) has been the best and well known electrocatalyst for the oxidation and reduction reactions in fuel cells. However, scarcity, high price and degradation of platinum as catalyst in fuel cell represent a challenge for commercial proposes.1,2 In recent years, there have been efforts to reduce the platinum loading, or even to eliminate it from the electrodes. It is therefore necessary to develop non-Pt catalytic materials available, cheap and electroactive to replace the precious metal. Carbon nanotubes doped with nitrogen (N-CNTs) have reached the point to become an alternative catalyst for oxygen reduction reaction (ORR) in fuel cells cathode. 3 There have been many studies concerning the synthesis of carbon nanotubes doped with nitrogen atoms using different carbon-nitrogen precursors using chemical vapor deposition (CVD) method and having a good electrocatalytic activity for oxygen reduction. Alexeyeva 4 synthesized N-CNTs using acetonitrile as carbon and nitrogen sources. They studied the electrocatalytic reduction of oxygen with and without doped nanotubes in 0.5M H 2 SO 4 solution where the N-CNTs show significantly more activity for ORR than the free-doping nanotubes. Wong 2 obtained N-CNTs through CVD technique using three different chemical precursors as nitrogen sources: aniline (A), diethylamine (DEA) and ethylenediamine. The analysis revealed that the N-CNTs obtained from EDA with 6.5 at. % N was more active for ORR in acidic medium than nanotubes from A and DEA with 5.9 at. % N and 4.3 at. % N, respectively. Other studies 1,[5][6][7][8] have also showed the important role of nitrogen precursors on the N-CNTs structure. Nevertheless, few...

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The formation of nitrogen-containing functional groups on carbon nanotube surfaces: a quantitative XPS and TPD study

Cited by 330 publications

References 42 publications

The Key to High Performance Low Pt Loaded Electrodes

The Key to High Performance Low Pt Loaded Electrodes

Catalytic activity and stability of multiwalled carbon nanotubes in catalytic wet air oxidation of oxalic acid: The role of the basic nature induced by the surface chemistry

Influence of the Synthesis Parameters in Carbon Nanotubes Doped with Nitrogen for Oxygen Electroreduction

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