Evolution of nitrogen functionalities in carbonaceous materials during pyrolysis
TL;DR: In this paper, X-ray photoelectron spectroscopy (XPS) was used to investigate the fate of nitrogen functional forms present in a lignite and its chars, derived from the model compounds acridine, carbazole and polyacrylonitrile (PAN).
About: This article is published in Carbon.The article was published on 1995-01-01. It has received 1792 citations till now. The article focuses on the topics: Char & Pyrolysis.
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TL;DR: In this paper, the oxygen reduction reaction (ORR) active site was characterized by using newly designed graphite (highly oriented pyrolitic graphite) model catalysts with well-defined π conjugation and well-controlled doping of N species.
Abstract: Nitrogen (N)-doped carbon materials exhibit high electrocatalytic activity for the oxygen reduction reaction (ORR), which is essential for several renewable energy systems. However, the ORR active site (or sites) is unclear, which retards further developments of high-performance catalysts. Here, we characterized the ORR active site by using newly designed graphite (highly oriented pyrolitic graphite) model catalysts with well-defined π conjugation and well-controlled doping of N species. The ORR active site is created by pyridinic N. Carbon dioxide adsorption experiments indicated that pyridinic N also creates Lewis basic sites. The specific activities per pyridinic N in the HOPG model catalysts are comparable with those of N-doped graphene powder catalysts. Thus, the ORR active sites in N-doped carbon materials are carbon atoms with Lewis basicity next to pyridinic N.
3,201 citations
TL;DR: This paper presents a probabilistic procedure for estimating the polymethine content of carbon dioxide using a straightforward two-step procedure, and shows good results in both the stationary and the liquid phase.
Abstract: Liming Dai,*,†,‡ Yuhua Xue,†,‡ Liangti Qu,* Hyun-Jung Choi, and Jong-Beom Baek* †Center of Advanced Science and Engineering for Carbon (Case4Carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Department of Chemistry, School of Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China School of Energy and Chemical Engineering/Center for Dimension-Controllable Covalent Organic Frameworks, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon, Ulsan, 689-798, South Korea
1,967 citations
TL;DR: Nitrogen-doped carbon nanofiber webs (CNFWs) with high surface areas are successfully prepared by carbonization-activation of polypyrrole nan ofiber webs with KOH, which exhibit a superhigh reversible capacity and porous nanostructure.
Abstract: Nitrogen-doped carbon nanofiber webs (CNFWs) with high surface areas are successfully prepared by carbonization-activation of polypyrrole nanofiber webs with KOH. The as-obtained CNFWs exhibit a superhigh reversible capacity of 943 mAh g(-1) at a current density of 2 A g(-1) even after 600 cycles, which is ascribed to the novel porous nanostructure and high-level nitrogen doping.
1,516 citations
TL;DR: In this article, the surface chemistry is affected by the type of nitrogen precursor and specific groups present on the surface before the treatment leading to the incorporation of nitrogen, and the most important functional groups affecting energy storage performance are pyrrolic and pyridinic nitrogen along with quinone oxygen.
Abstract: Microporous activated carbon originating from coconut shell, as received or oxidized with nitric acid, is treated with melamine and urea and heated to 950 °C in an inert atmosphere to modify the carbon surface with nitrogen- and oxygen-containing groups for a systematic investigation of their combined effect on electrochemical performance in 1 M H2SO4 supercapacitors. The chemistry of the samples is characterized using elemental analysis, Boehm titration, potentiometric titration, and X-ray photoelectron spectroscopy. Sorption of nitrogen and carbon dioxide is used to determine the textural properties. The results show that the surface chemistry is affected by the type of nitrogen precursor and the specific groups present on the surface before the treatment leading to the incorporation of nitrogen. Analysis of the electrochemical behavior of urea- and melamine-treated samples reveal pseudocapacitance from both the oxygen and the nitrogen containing functional groups located in the pores larger than 10 A. On the other hand, pores between 5 A and 6 A are most effective in a double-layer formation, which correlates well with the size of hydrated ions. Although the quaternary and pyridinic-N-oxides nitrogen groups have enhancing effects on capacitance due to the positive charge, and thus an improved electron transfer at high current loads, the most important functional groups affecting energy storage performance are pyrrolic and pyridinic nitrogen along with quinone oxygen. (C)2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
1,409 citations
TL;DR: The physicochemical properties and the surface chemical structure of the carbon materials obtained by the modification of the commercial activated carbon D43/1 (Carbo-Tech, Essen, Germany) were studied in this article.
1,342 citations
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TL;DR: In this article, X-ray photoelectron spectroscopy (XPS) was used to identify and quantify the organically bound nitrogen forms present in fresh Argonne Premium coals.
Abstract: X-ray photoelectron spectroscopy (XPS) was used to identify and quantify the organically bound nitrogen forms present in fresh Argonne Premium coals. XPS spectra obtained on a wide variety of model compounds were used to establish a curve resolution methodology. Pyrrolic nitrogen is the moat abundant form of organically bound nitrogen, followed by pyridinic types. Quaternary nitrogen species were also identified. An analysis of the sensitivity of XPS for primary amines indicates that these species are not detected at concentrations above 5 mol %. A trend of decreasing level of quaternary nitrogen forms along with increasing levels of pyridinic nitrogen was observed with increasing coal rank. The formation and reactivity of quaternary nitrogen forms in several coals were examined
282 citations
TL;DR: In this article, four commercially available carbons were subjected to ammonia and ammonia/oxygen gas mixtures at temperatures between 200 and 420°C. The pore structure of the carbons, as determined by nitrogen porosimetry, was virtually unchanged after the treatments.
262 citations