Cobalt phthalocyanine crystal synthesized at low temperature

Enokida, Toshio; Hirohashi, Ryo

doi:10.1021/cm00017a030

Cited by 30 publications

(20 citation statements)

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“…Evidence for the presence of surface nitrogen (N1s peak, see Fig. 9b) is a single peak centered at 399.0 eV, in agreement with the literature [68][69][70]; there is little separation (e.g., 0.28 eV as a shift in Pb-Pc [71]) between the four equivalent aza-type nitrogens and four equivalent pyrrole-type nitrogens (for both Co-and Cu-Pc). The decrease in surface nitrogen content with HTT is consistent with the disappearance of the C1s peak at 285.7 eV (attributed to carbon-nitrogen bonding, as mentioned above) and is practically undetected at 850°C and above.…”

Section: Effect Of Httsupporting

confidence: 89%

Pyrolyzed phthalocyanines as surrogate carbon catalysts: Initial insights into oxygen-transfer mechanisms

Vallejos-Burgos

Utsumi

Hattori

et al. 2012

Fuel

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a b s t r a c tDeposited and heat-treated phthalocyanines are promising electrocatalysts for replacing platinum in the oxygen reduction reaction (ORR), the most important process in energy conversion systems such as fuel cells; and yet its key mechanistic features are not well understood. To optimize their use, it is necessary to understand their behavior in the absence of an electric field. In the pursuit of this goal, we pyrolyzed metal-free, cobalt and copper phthalocyanines between 550 and 1000°C and studied their structural and chemical changes by elemental analysis, N 2 and CO 2 adsorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray analysis fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS). Their catalytic activity was assessed by non-isothermal O 2 gasification and NO reduction reactions. A comparison of these results with their other properties allowed us to reach the following conclusions: (i) the loss of reactivity of metal-free phthalocyanine with heat treatment is attributed to its structural annealing and heteroatom loss, with the porosity changes having no effect; (ii) for metal phthalocyanines at intermediate heat treatment temperatures, the optimum in reactivity correlates with the micropore surface area and the presence of metal particles, with no influence of nitrogen content; (iii) the coordination metal increases phthalocyanine thermal stability in an inert atmosphere, but in an oxidizing atmosphere it acts as a gasification catalyst even below decomposition temperatures. The implications of these findings for catalytic oxygen-transfer mechanisms are discussed.

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Section: Effect Of Httsupporting

confidence: 89%

Pyrolyzed phthalocyanines as surrogate carbon catalysts: Initial insights into oxygen-transfer mechanisms

Vallejos-Burgos

Utsumi

Hattori

et al. 2012

Fuel

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“…In previous work, attention is devoted to the nanoscopic materials of metals and simple inorganic semiconductors (1)(2)(3)(4)(5)(6)(7)(8)(9)(10), whereas reports on the preparation and properties of nanoscopic organic semiconductors have so far been scarce. A few works about the size effect on the absorption properties and charge generation efficiency of metal-free phthalocyanine particles (average particle size larger than 100 nm) prepared by the traditional milling method have been reported (11,12). It has been concluded that smaller-size pigment particles exhibit higher carrier generation efficiency within the examined particle size region.…”

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confidence: 99%

Preparation and Characterization of Nanoscopic Organic Semiconductor of Oxovanadium Phthalocyanine

Wang

Deng

Liu

et al. 1999

Journal of Colloid and Interface Science

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“…Out-of-plane CC bending (γ CC ) in the range between 850 and 960 cm ¹1 and out-of-plane CH bending (γ CH ) and CH stretching (ν CH ) at 1370 cm ¹1 were observed. 4 The peaks of β-CoPc had larger number than those of α-CoPc showing dense molecular packing with larger van der Walls' force. A broad peak at around 1700 cm ¹1 attributed to C=O stretching mode (ν C=O ) in CF 3 COOH was not observed in the α-CoPc powder prepared by the neutralization method.…”

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confidence: 93%

“…It was revealed that the commercial powder had a β-CoPc structure, while the powders treated with KOH and NaOH solutions gave α-phase MPcs. α-Phase CoPc was not obtained from the NH 4 OH solution, although the specific phase of polymorphic structure could not be identified. The results indicate that monomolecular CoPc in liquid preferentially forms α-phase with a dominant effect of ππ interaction, similar to the behavior in vacuum conditions.…”

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confidence: 97%

“…The results indicate that monomolecular CoPc in liquid preferentially forms α-phase with a dominant effect of ππ interaction, similar to the behavior in vacuum conditions. When NH 4 OH was used, NH 4 + ions seem to act as ligands in the phthalocyanine and prevented the formation of α-phase CoPc. FT-IR spectra of the powders of α-CoPc, β-CoPc, and β-CoPc mixed with CF 3 COOH are shown in Figure 2.…”

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Processing of α-Phase Metal–Phthalocyanine Powders by Interface Neutralization Method

Takase¹,

Aoto²

2016

Chem. Lett.

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Metal phthalocyanines (MPcs; M = Co, Ni, Cu, Zn) with α-phase powders were obtained at the interface between hydrophilic and hydrophobic solutions starting from β-phase powders. This method was also applied to the deposition of a highly dispersed α-phase MPc on a carbon substrate, which showed high electrochemical activity for oxygen reduction. Metal phthalocyanines (MPcs) with a divalent transitionmetal ion at the center of a phthalocyanine ring are twodimensional 18π-electron aromatic porphyrin analogs, and have been extensively studied due to a specific catalytic property, and electrical and/or magnetic properties for application as electrocatalysts 1 and semiconductors in various electronic devices. 2Their properties are due not only to the types of the central metals 3 but also to the polymorphic structures of MPcs. 48 MPc forms various stacking constructions by ππ interaction between two MPc molecules. The distance between the central metals and the stacking angle of the molecular plane determined the electronic conductivities and the catalytic properties of MPc.It is well known that MPcs have two major phases, i.e., α-and β-phase. Although monomolecular MPc preferentially forms an α-phase by a large ππ interaction with overlapping areas of macrocyclic ligands, 8 α-MPc powders have not been applied to catalytic and electrochemical devices despite their low resistances 5 and high chemical activities, 9 because α-MPc powders are difficult to prepare by organic synthesis methods and the formed α-MPcs are easy to transform to a more stable β-MPc structure that is densely packed with large van der Waals' force. 5,10Thin films of α-MPcs have mostly been prepared with vacuum deposition systems because of their poor solubility in solvents. They have been used in electrical devices like solar cells 11 and chemical sensors. 12,13 However, an α-MPc thin film should be less than 40 nm in thickness for preventing transformation to β-phase.14 It seems that α-MPc is not stable under the condition of a dense molecular assemblage, in which the ππ interaction is dominant. If stable α-MPc powders are prepared without a dense molecular assemblage, they could provide high performance for electrocatalysts and materials. So far, α-MPcs have been prepared only under a vacuum condition; however, these methods are not appropriable for powder preparation. It was reported that α-MPc thin films could be prepared from an organic solution containing trifluoroacetic acid (TFA). 1519In this study, we tried to establish a new process for the preparation of α-MPc by a solution route, in which protonated MPcs are neutralized and deposited as powders at the interface between organic and aqueous solutions. We could also apply this method to deposit the MPc on carbon black for a highperformance oxygen reduction electrode.Commercially available MPc (M = Co, Ni, Cu, Zn) powders were used without further purification. CoPc and CuPc were purchased from Tokyo Chemical Industry, and NiPc and ZnPc were purchased from Kishida Chemical and Kanto Chemic...

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Cobalt phthalocyanine crystal synthesized at low temperature

Cited by 30 publications

References 0 publications

Pyrolyzed phthalocyanines as surrogate carbon catalysts: Initial insights into oxygen-transfer mechanisms

Pyrolyzed phthalocyanines as surrogate carbon catalysts: Initial insights into oxygen-transfer mechanisms

Preparation and Characterization of Nanoscopic Organic Semiconductor of Oxovanadium Phthalocyanine

Processing of α-Phase Metal–Phthalocyanine Powders by Interface Neutralization Method

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