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7732-18-5Relevant articles and documents
Oxygen electroreduction on heat-treated multi-walled carbon nanotubes supported iron polyphthalocyanine in acid media
Zhang, Rui,Peng, Yingxiang,Li, Zhipan,Li, Kai,Ma, Jie,Liao, Yi,Zheng, Lirong,Zuo, Xia,Xia, Dingguo
, p. 343 - 351 (2014)
Multi-walled carbon nanotubes (MWCNTs) supported iron phthalocyanine (FePc), binuclear iron phthalocyanine (bi-FePc) and iron polyphthalocyanine (FePPc) were prepared by a solvothermal process. The resulting FePc/MWCNTs, bi-FePc/MWCNTs and FePPc/MWCNTs were heat-treated in argon (Ar) atmosphere at various temperatures ranging from 500 to 900°C to obtain optimized catalysts for the oxygen reduction reaction (ORR). The crystal structure, morphology and chemical environment of the catalysts were examined by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure spectroscopy (XAFS). The electrocatalytic activity of the obtained catalysts was measured using a rotating disk electrode (RDE) technique in 0.5 mol L-1 H2SO4 solution saturated with oxygen. The ORR activity of the heat-treated FePPc/MWCNTs was found to be better than that of the heat-treated bi-FePc/MWCNTs and FePc/MWCNTs. Furthermore, the heat-treatment temperature greatly influenced the catalytic ORR ability of the catalysts. The FePPc/MWCNTs heat-treated at 800°C exhibited a four-electron transfer process and the best ORR activity (EORR = 0.79 V vs. RHE), methanol resistance, and stability (current loss = 13% at -0.13 V vs. Hg/Hg2SO4 after 55 h). XPS indicated that pyridine-type nitrogen, not graphitic-N, played a critical role in determining the electrocatalytic ORR activity of the amples. XAFS showed that the coordination geometry around Fe was close to square planar in structure, suggesting that the Fe-N4 structure was produced by the high temperature treatment.
Ni2P hollow microspheres for electrocatalytic oxygen evolution and reduction reactions
Lei, Haitao,Chen, Mingxing,Liang, Zuozhong,Liu, Chengyu,Zhang, Wei,Cao, Rui
, p. 2289 - 2293 (2018)
H2 generated by solar-driven water splitting is a clean and environmentally benign fuel and is an ideal alternative to replace fossil fuels, whose uses have caused a series of energy and environmental issues. The synthesis of Ni2P and its catalytic properties foroxygen evolution reduction (OER) and oxygen reduction reaction (ORR) was reported. The as-prepared Ni2P material has a hollow microsphere structure, which has a very high surface-to-volume ratio and is beneficial for fast charge transfer and mass diffusion. These features are useful for electrocatalysis. The high activities and stabilities of this Ni2P material for both OER and ORR were confirmed, representing a rare example of bifunctional OER and ORR catalysts among Ni phosphides. Results showed that NI2P can catalyze water oxidation, achieving a 10 mA cm-2 current density at a 280 mV overpotential and can catalyze the selective four-electron reduction of O2 to H2O at an onset potential of 0.92 V, making it one of the most active metal phosphide catalysts for OER and ORR.
Tuning Cobalt and Nitrogen Co-Doped Carbon to Maximize Catalytic Sites on a Superabsorbent Resin for Efficient Oxygen Reduction
Liu, Mengran,Lin, Hai,Mei, Zongwei,Yang, Jinlong,Lin, Jie,Liu, Yidong,Pan, Feng
, p. 3631 - 3639 (2018)
The electrocatalytic performance and cost of oxygen reduction reaction (ORR) catalysts are crucial to many renewable energy conversion and storage systems/devices. Recently, transition-metal/nitrogen-doping carbon catalysts (M–N–C) have attracted tremendous attention due to their low cost and excellent catalytic activities; however, they are restricted in large-scale commercial applications by complex preparation processing. Here, a facile strategy to prepare Co–N–C catalysts has been developed. A kind of superabsorbent resin normally found in diapers, poly(acrylic acid-acrylamide), is used to adsorb a transition-metal cobalt salt and a pyrolysis strategy at 800 °C under an argon atmosphere is followed. The resin simultaneously plays a multiple role, which includes structural support, dispersing cobalt ions by coordinate bonds, and providing a carbon and nitrogen source. Attributed to the conductive carbon frameworks and abundant catalytic sites, the Co–N–C catalyst exhibits an excellent electrocatalytic performance. High onset potential (0.96 V vs. reversible hydrogen electrode, RHE), half-wave potential (0.80 V vs. RHE), and a large diffusion-limited current density (4.65 mA cm?2) are achieved for the ORR, which are comparable or superior to the commercial 20 % Pt/C and reported M–N–C ORR electrocatalysts. This work provides a universal dispersion technology for Co–N–C catalyst, which makes it a very promising candidate toward the ORR.
Synthesis, electrochemistry and electrocatalytic activity of cobalt phthalocyanine complexes – Effects of substituents for oxygen reduction reaction
Acar, Elif Turker,Tabakoglu, Tuba Akk?zlar,Atilla, Devrim,Yuksel, Fatma,Atun, Gulten
, p. 114 - 124 (2018)
The synthesis, characterization, electrochemistry and electrocatalytic activity of the mono (pyridine-4-oxy)-tri (tert-butyl) phthalocyaninato Co(II) (Pc1) and mono (pyridine-4-oxy)-hexa (hexyl) phthalocyaninato Co(II) (Pc2) are reported here. One reversi
Mechanism of the low-temperature interaction of hydrogen with α-oxygen on FeZSM-5 zeolite
Dubkov,Starokon',Paukshtis,Volodin,Panov
, p. 202 - 208 (2004)
The mechanism of a low-temperature reaction of hydrogen with the radical anion surface oxygen species (α-oxygen, Oα) formed by decomposing N2O over FeZSM-5 zeolite was studied using kinetic and isotope techniques. It was found that the reaction is of first order with respect to hydrogen and the rate of the reaction is proportional to the concentration of Oα. The activation energy of the reaction, which was measured for H2 or D2 over a temperature range from +20 to -100°C, is equal to 3.2 or 5.3 kcal/mol, respectively. The reaction occurs with a considerable kinetic isotope effect (kH/k D), which varies over the range of 3.4-41 depending on the temperature. This fact indicates that the rate-limiting step of the reaction includes the dissociation of the hydrogen molecule. The temperature dependence of the isotope effect gave a value of 2.1 kcal/mol, which is close to the difference between the zero bond energies in the molecules of H2 and D2; this fact suggests that a tunnel effect does not significantly contribute to the reaction. The dissociative mechanism is consistent with data obtained by in situ IR spectroscopy. The interaction of hydrogen with α-oxygen is accompanied by the formation of new hydroxyl groups O αH (absorption bands at 3635 and 3674 cm-1) at the surface of the zeolite. The identification of these groups was supported by an isotope shift either on the replacement of H2 by D2 or on the replacement of 16Oα by Oα,. The stoichiometric ratio H2:Oα, is consistent with the previously drawn conclusion on the paired arrangement of α-sites.
A four-electron O2-electroreduction biocatalyst superior to platinum and a biofuel cell operating at 0.88 V
Soukharev, Valentine,Mano, Nicolas,Heller, Adam
, p. 8368 - 8369 (2004)
O2 was electroreduced to water, at a true-surface-area-based current density of 0.5 mA cm-2, at 37 °C and at pH 5 on a wired laccase bioelectrocatalyst-coated carbon fiber cathode. The polarization (potential vs the reversible potential of the O2 /H2O half-cell in the same electrolyte) of the cathode was only -0.07 V, approximately one-fifth of the -0.37 V polarization of a smooth platinum fiber cathode, operating in its optimal electrolyte, 0.5 M H2SO4. The bioelectrocatalyst was formed by wiring laccase to carbon through an electron conducting redox hydrogel, its redox functions tethered through long and flexible spacers to its cross-linked and hydrated polymer. Incorporation of the tethers increased the apparent electron diffusion coefficient 100-fold to (7.6 ± 0.3) × 10-7 cm 2 s-1. A miniature single-compartment glucose-O2 biofuel cell made with the novel cathode operated optimally at 0.88 V, the highest operating voltage for a compartmentless miniature fuel cell. Copyright
2D Layered non-precious metal mesoporous electrocatalysts for enhanced oxygen reduction reaction
Huo, Lili,Liu, Baocang,Zhang, Geng,Si, Rui,Liu, Jian,Zhang, Jun
, p. 4868 - 4878 (2017)
Rational design of inexpensive, highly active, and long-term stable non-precious metal electrocatalysts for oxygen reduction reaction (ORR) is of significant importance for large-scale applications of fuel cells in practice. In this paper, we report, for the first time, the construction of 2D layered mesoporous transition metal-nitrogen-doped carbon/nitrogen-doped graphene (meso-M-N-C/N-G, M = Fe, Co, and Ni) electrocatalysts using 4,4-bipyridine as the nitrogen and carbon source and mesoporous KIT-6/N-G generated by in situ formation of KIT-6 on graphene nanosheets as a template. The meso-Fe-N-C/N-G electrocatalyst showed super electrocatalytic performance for ORR. Excitingly, its catalytic activity and durability were superior to those of Pt/C, making it a good candidate as an ORR electrocatalyst in fuel cells. The results suggested that the outstanding electrocatalytic performance of the electrocatalysts could be attributed to the unique mesoporous structure, high surface area, ultrasmall size of Fe or FeOx nanocrystals embedded in 2D layered N-G nanosheets, excellent electron transportation, homogeneous distribution of high-density pyridinic N and graphitic N, graphitic C, and abundant metal active sites (Fe-Nx). The synthesis approach can be used as a versatile route toward the construction of various 2D layered graphene-based mesoporous materials.
Rational Design of Hierarchical, Porous, Co-Supported, N-Doped Carbon Architectures as Electrocatalyst for Oxygen Reduction
Qiao, Mengfei,Wang, Ying,Mamat, Xamxikamar,Chen, Anran,Zou, Guoan,Li, Lei,Hu, Guangzhi,Zhang, Shusheng,Hu, Xun,Voiry, Damien
, p. 741 - 748 (2020)
Developing highly active nonprecious-metal catalysts for the oxygen reduction reaction (ORR) is of great significance for reducing the cost of fuel cells. 3D-ordered porous structures could substantially improve the performance of the catalysts because of their excellent mass-diffusion properties and high specific surface areas. Herein, ordered porous ZIF-67 was prepared by forced molding of a polystyrene template, and Co-supported, N-doped, 3D-ordered porous carbon (Co-NOPC) was obtained after further carbonization. Co-NOPC exhibited excellent performance for the ORR in an alkaline medium with a half-wave potential of 0.86 V vs. reversible hydrogen electrode (RHE), which is higher than that of the state-of-the-art Pt/C (0.85 V vs. RHE). Moreover, the substantially improved catalytic performance of Co-NOPC compared with Co-supported, N-doped carbon revealed the key role of its hierarchical porosity in boosting the ORR. Co-NOPC also exhibited a close-to-ideal four-electron transfer path, long-term durability, and resistance to methanol penetration, which make it promising for large-scale application.
2H→1T Phase Engineering of Layered Tantalum Disulfides in Electrocatalysis: Oxygen Reduction Reaction
Luxa, Jan,Mazánek, Vlastimil,Pumera, Martin,Lazar, Petr,Sedmidubsky, David,Callisti, Mauro,Polcar, Tomá?,Sofer, Zdeněk
, p. 8082 - 8091 (2017)
Tremendous attention is currently being paid to renewable sources of energy. Transition-metal dichalcogenides (TMDs) have been intensively studied for their promising catalytic activities in the hydrogen evolution reaction (HER) and the oxygen reduction reaction (ORR). In this fundamental work, we explored the catalytic properties of TMD family members 2H TaS2 and 1T TaS2. Our findings reveal that both polytypes exhibit poor HER performance, which is even more pronounced after electrochemical reduction/oxidation. Our experimental data show that 1T TaS2 has a lower overpotential at a current density of ?10 mA cm?1, despite theoretical DFT calculations that indicated that the more favorable free energy of hydrogen adsorption should make “perfect” 2H TaS2 a better HER catalyst. Thorough characterization showed that the higher conductivity of 1T TaS2 and a slightly higher surface oxidation of 2H TaS2 explains this discrepancy. Moreover, changes in the catalytic activity after electrochemical treatment are addressed here. For the ORR in an alkaline environment, the electrochemical treatment led to an improvement in catalytic properties. With onset potentials similar to that of Pt/C catalysts, TaS2 was found to be an efficient catalyst for the ORR, rather than for proton reduction, in contrast to the behavior of Group 6 layered TMDs.
Bifunctional gold-manganese oxide nanocomposites: Benign electrocatalysts toward water oxidation and oxygen reduction
Rahaman, Hasimur,Barman, Koushik,Jasimuddin, Sk,Ghosh, Sujit Kumar
, p. 41976 - 41981 (2014)
Gold-manganese oxide nanocomposites were synthesised by seed-mediated epitaxial growth at the water/n-heptane interface under mild reflux conditions. These nanocomposites exhibit efficient electrocatalytic activity toward the water oxidation reaction (WOR) and the simultaneous oxygen reduction reaction (ORR) at a low overpotential (η ≈ 370 mV) and under neutral pH conditions. This journal is
