Preparation and oxygen reduction activity of BN-doped carbons

Ozaki, Jun‐ichi; Kimura, Naofumi; Anahara, Tomonori; Ōya, Asao

doi:10.1016/j.carbon.2007.04.031

Cited by 322 publications

(253 citation statements)

References 18 publications

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“…Although the usual reaction that occurs on carbon electrodes is far less than the four-electron reaction (O 2 + 4 H + + 4 e -→ H 2 O), there have been reports that reactions involving more electrons may take place on nitrogen-containing carbon electrodes [2][3][4][5][6]. Analyses of the ORR by a method involving a rotating ring-disk electrode showed that the ORR on CS900-AC proceeds by a 3.5-electron reaction to give about 25% of hydrogen peroxide (Fig.…”

Section: Resultsmentioning

confidence: 99%

High oxygen-reduction activity of silk-derived activated carbon

Iwazaki

Obinata

Sugimoto

et al. 2009

Electrochemistry Communications

116

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Activated carbon prepared from silk fibroin, which is free of metal elements, showed a high catalytic activity for the oxygen-reduction reaction (ORR). The activated carbon had a very high onset potential of E onset = 0.83 V (vs. RHE) in oxygen saturated 0.5 M H 2 SO 4 at 60 °C. The ORR on the activated carbon proceeded by a four-electron process in the high-electrode-potential region; this gradualy decreased to a 3.5-electron reaction below about 0.6 V (vs. RHE). Only about 1 % of nitrogen atoms (mostly quaternary) remained in the activated carbon by heat treatment at up to 1200 °C are responsible for the high catalytic activity. The open circuit voltage of a polymer electrolyte fuel cell using the activated carbon as the cathode and a platinum/carbon black anode under pure oxygen and hydrogen gases, respectively, both at 1 atmosphere, was 0.96 V at 27 °C.

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Section: Resultsmentioning

confidence: 99%

High oxygen-reduction activity of silk-derived activated carbon

Iwazaki

Obinata

Sugimoto

et al. 2009

Electrochemistry Communications

116

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“…It must be noted that this high performance was attained with a cathode containing no metal elements at all. Although the usual reaction that occurs on graphite electrodes is nearly always the two-electron reaction, there have been reports that reactions involving more electrons may take place on nitrogen-containing carbon electrodes [11,[17][18][19][20]24]. Analyses of the ORR by a method involving a rotating ring disk electrode showed that the ORR on CS900-AC proceeds by a 3.5-electron reaction at 0.6 V vs. RHE, for example Fig.…”

Section: Performance Of a Pefc With A Cs-acmentioning

confidence: 99%

“…Various kinds of carbon materials prepared by carbonization of nitrogen containing polymers, such as polyacrylonitrile, or metal complexes have been proposed as candidate cathode materials for the ORR, and are activated with metal salts or contain metal species themselves [4][5][6][7][8][9][10][11]. The most important feature of the CSs and CS-ACs is that they contain no metal species at all.…”

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confidence: 99%

Oxygen-reduction activity of silk-derived carbons

Iwazaki

Yang

Obinata

et al. 2010

Journal of Power Sources

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Carbonized silk fibroin (CS), which is free of metallic elements, showed high catalytic activity for oxygen-reduction reaction (ORR). The catalytic activity of CS for ORR was greatly enhanced by steam activation forming silk-derived activated carbon (CS-AC). The surface morphology, surface area, pore structure and remaining nitrogen species of the CSs were compared with those of the CS-ACs. The open-circuit potential and the power density of a polymer electrolyte fuel cell using a CS900-AC, which was heat-treated at 900°C prior to the steam activation, and a platinum/C (C: carbon black) anode under pure oxygen and hydrogen gases, respectively, both at 0.2 MPa, were 0.92 V and 142 mW cm -2 at 80°C. The ORR on the 1 activated carbon, CS900-AC, proceeded with a 3.5-electron reaction at 0.6 V (vs. RHE);however, this was improved to a 3.9-electron reaction with the addition of zirconium oxide at 20 wt% to CS900-AC. Durability test of the electrode was also performed in O 2 -saturated HClO 4 solution.

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“…Bitter et al suggest the importance of pyridine type doped nitrogen species for the genesis of catalytic activity [4]. A theoretical study indicates that carbon atoms at edge sites of graphite sheets may interact with oxygen molecules with the aid of adjacent doped nitrogen atoms [6]; then, the nitrogen-doped carbon can show a good performance as a Pt-free electrode in proton-exchange membrane fuel cells [7]. Thomas et al show that their well-designed synthetic carbon nitride materials can catalyze Friedel−Craft and cyclization reactions [8].…”

Section: Introductionmentioning

confidence: 99%

Nitrogen-Doped Activated Carbon as Metal-Free Catalysts Having Various Functions

Fujita¹,

Yoshida²,

Arai³

2017

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Nitrogen-doped carbon materials have been gaining increasing interest as metal-free catalysts. In this article, the authors have briefly introduced their recent studies on the utilization of nitrogen-doped activated carbon (N-AC) for several organic synthesis reactions, which include base catalyzed reactions of Knoevenagel condensation and transesterification, aerobic oxidation of xanthene and alcohols, and transfer hydrogenation of nitrobenzene, 3-nitrostyrene, styrene, and phenylacetylene with hydrazine. Doped-nitrogen species existed on the AC surface in different structures. For example, pyridine-type nitrogen species appear to be involved in the active sites for Knoevenagel condensation and for the oxidation of xanthene, while graphite-type nitrogen species appear to be involved for the oxidation of alcohols. Being different from these reactions, both surface nitrogen and oxygen species are involved in the active sites for the hydrogenation of nitrobenzene. N-AC was practically inactive for the transfer hydrogenation of vinyl and ethynyl groups, but it can catalyze those hydrogenation reactions assisted by co-existing nitrobenzene. Comparison of N-AC with conventional catalysts shows that N-AC can alternate with conventional solid base catalysts and supported metal catalysts for the Knoevenagel condensation and oxidation reactions.Keywords: activated carbon; ammoxidation; solid base; aerobic oxidation; transfer hydrogenation IntroductionVarious catalysts are used in industry [1], in which suitable active components are selected and tailored into an effective catalyst for a target reaction under optimized conditions. That is, different catalyst components are selected and used according to target production processes. It is interesting to design and prepare a catalyst, single or multi-component, that can have different active sites on its surface and act as a multifunctional catalyst: the same catalyst can be effectively used for different types of synthetic reaction. One of potential components for such a multifunctional catalyst may be carbon.Carbon is an interesting material, due to its physicochemical and electrochemical properties and has been used as one of the industrial functional materials. It is also important as either a carrier or a catalyst in the field of catalysis. The carbon materials have a few different functional groups on their surface, depending on their sources and carbonization processes, and these are catalytically active in chemical reactions like oxidation [2]. Their surface functionalization can further be made by doping foreign species, such as nitrogen [3]. Nitrogen-doped carbon and carbon nitride would be interesting functional materials. Those modified carbon materials are prepared by different methods, including chemical vapor deposition, well-designed organic synthesis, and doping of nitrogen to parent bulk carbon materials (say, activated carbon). In addition to their effectiveness in electrochemical applications, those carbon-based materials will serve as metal-fr...

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Preparation and oxygen reduction activity of BN-doped carbons

Cited by 322 publications

References 18 publications

High oxygen-reduction activity of silk-derived activated carbon

High oxygen-reduction activity of silk-derived activated carbon

Oxygen-reduction activity of silk-derived carbons

Nitrogen-Doped Activated Carbon as Metal-Free Catalysts Having Various Functions

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