耐超高温SiC(Al)纤维先驱体——聚铝碳硅烷纤维的研究

以聚硅碳硅烷(PSCS)与乙酰丙酮铝(Al(AcAc)3)为原料,在常压高温条件下反应制备出聚铝碳硅烷(PACS),经过熔融纺丝制备了PACS纤维.应用GPC、IR、XPS、29Si-NMR、27Al-NMR、TG、SEM、元素分析和增重等一系列分析,分别对PACS纤维的微观组成、结构以及性能进行了分析.研究结果表明,以原料质量配比为6∶100(Al(AcAc)3∶PSCS)合成的PACS化学式为SiC2.0H7.5O0.13Al0.018,数均分子量为1700左右,最适宜制备PACS纤维;PACS纤维中主要存在SiC4、SiC3H等结构,同时存在Si—O—Al键;在氮气气氛中,PACS纤维的陶瓷产率达到52%左右;预氧化处理,PACS纤维中Si—H键与空气中的氧反应形成Si—O—Si交联结构,较聚碳硅烷(PCS)纤维易于氧化,经过预氧化的PACS纤维陶瓷产率达到80%左右,是制备耐超高温SiC(Al)陶瓷纤维的合适纤维;用预氧化PACS纤维制备的SiC(OAl)纤维和SiC(Al)纤维抗拉强度高,耐高温性能好.     

铝含量对含铝碳化硅陶瓷先驱体结构和性能的影响

采用不同比例的乙酰丙酮铝[Al(AcAc)3]与聚硅碳硅烷(PSCS)反应制备含铝碳化硅陶瓷的先驱体聚铝碳硅烷(PACS). 采用气相凝胶色谱(GPC)、化学分析和红外等手段对不同铝含量的PACS组成和结构进行了表征, 研究了铝含量对PACS结构和性能的影响. 结果表明, 随着铝含量的增加, PACS的氧含量增加, 分子量分布变宽, 主要活性基团Si—H键的含量降低, PACS的可纺性降低. 当Al(AcAc)3/PSCS(质量比)大于20%以后, PACS不可纺. 热重-差热分析(TG-DTA)的研究表明: 当制备PACS的Al(AcAc)3/PSCS(质量比)大于4%, PACS在N2中400～560 ℃之间的失重明显降低. 铝含量在0.4～0.7 wt%的PACS, 制备的Si-Al-C-O纤维抗张强度最高. Al(AcAc)3/PSCS＝6 wt%时制备的PACS, 烧结的SiC(Al)纤维最致密.     

Six‐coordinated vanadium(IV) complexes with tridentate task‐specific ionic liquid Schiff base ligands: Synthesis,characterization and effect of ionic nature on catalytic activity

By reaction of 5‐(chloromethyl)salicylaldehyde with triphenylphosphine and N‐methylimidazole in two separate reactions, salicylaldehydetriphenylphosphonium chloride (S²) and salicylaldehydemethylimidazolinium chloride (S³) were prepared. Reaction of 2‐(aminomethyl)pyridine with these aldehydes resulted in the task‐specific ionic liquid Schiff base ligands L¹ and L², respectively. Then six‐coordinated vanadium(IV) Schiff base complexes of VO(acac)L^1–4 were synthesized by reactions of these tridentate Schiff base ligands and VO(acac)₂ in 1:1 stoichiometry. The aldehydes, ligands and VO(acac)L^1–4 complexes were characterized using infrared, ¹H NMR, ¹³C NMR, ³¹P NMR, UV–visible and mass spectroscopies, as well as elemental analysis. Paramagnetic property of the complexes was also studied using magnetic susceptibility measurements. The complexes were used as catalysts in epoxidation of cyclooctene and oxidation of methylphenyl sulfide and the reaction parameters were optimized. The effect of the ionic nature of the complexes was investigated in these oxidation reactions. The catalytic activity of the complexes could be varied by changing the ionic (cationic or anionic) character of VO(acac)L^1–4 catalysts in which counter anion variation showed a greater effect than cationic moiety variation.     

Stereospecific and molecular weight‐controlled polymerization of 1,3‐butadiene with Co(acac)3‐MAO catalyst

The polymerization of butadiene (Bd) with Co(acac)₃ in combination with methylaluminoxane (MAO) was investigated. The polymerization of Bd with Co(acac)₃‐MAO catalysts proceeded to give cis‐1,4 polymers (94 – 97%) bearing high molecular weights (40 × 10⁴) with relatively narrow molecular weight distributions (M_w's/M_n's). The molecular weight of the polymers increased linearly with the polymer yield, and the line passed through an original point. The polydispersities of the polymers kept almost constant during reaction time. This indicates that the microstructure and molecular weight of the polymers can be controlled in the polymerization of Bd with the Co(acac)₃‐MAO catalyst. The effects of reaction temperature, Bd concentration, and the MAO/Co molar ratio on the cis‐1,4 microstructure and high molecular weight polymer in the polymerization of Bd with Co(acac)₃‐MAO catalyst were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2793–2798, 2001     

Polymerization of 3‐ethynylthiophene with homogeneous and heterogeneous Rh catalysts

3‐Ethynylthiophene (3ETh) was polymerized with Rh(I) complexes: [Rh(cod)acac], [Rh(nbd)acac], [Rh(cod)Cl]₂, and [Rh(nbd)Cl]₂ (cod is η²:η²‐cycloocta‐1,5‐diene and nbd η²:η²‐norborna‐2,5‐diene), used as homogeneous catalysts and with the last two complexes anchored on mesoporous polybenzimidazole (PBI) beads: [Rh(cod)Cl]₂/PBI and [Rh(nbd)Cl]₂/PBI used as heterogeneous catalysts. All tested catalyst systems give high‐cis poly(3ETh). In situ NMR study of homogeneous polymerizations induced with [Rh(cod)acac] and [Rh(nbd)acac] complexes has revealed: (i) a transformation of acac ligands into free acetylacetone (Hacac) occurring since the early stage of polymerization, which suggests that this reaction is part of the initiation, (ii) that the initiation is rather slow in both of these polymerization systems, and (iii) a release of cod ligand from [Rh(cod)acac] complex but no release of nbd ligand from [Rh(nbd)acac] complex during the polymerization. The stability of diene ligand binding to Rh‐atom in [Rh(diene)acac] catalysts remarkably affects only the molecular weight but not the yield of poly(3ETh). The heterogeneous catalyst systems also provide high‐cis poly(3ETh), which is of very low contamination with catalyst residues since a leaching of anchored Rh complexes is negligible. The course of heterogeneous polymerizations is somewhat affected by limitations arising from the diffusion of monomer inside catalyst beads. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2776–2787, 2008     

Hyperbranched bisphosphinoamine ligands: synthesis,characterization and application in ethylene oligomerization

Two hyperbranched bisphosphinoamine (PNP) ligands and chromium complexes were synthesized in good yield with 1.0 generation (1.0 G) hyperbranched macromolecules, chlorodiphenylphosphine (Ph₂PCl) and CrCl₃(THF)₃ as raw materials. The hyperbranched PNP ligands and chromium complexes were characterized by FT-IR, ¹H NMR, ³¹P NMR, UV and ESI-MS. Comparing with the chromium complexes, the hyperbranched PNP ligands, in combination with Cr(III), and activation by methylaluminoxane (MAO) in situ generated species with better catalytic performance for ethylene oligomerization. The effect of solvent, chromium source, ligand/Cr molar ratio, reaction temperature, Al/Cr molar ratio and reaction pressure on the catalytic activity and product selectivity were studied. The results showed that with increase of ligand/Cr molar ratio, reaction temperature and Al/Cr molar ratio, the catalytic activity increased at first and then decreased. However, the catalytic activity continuously increased with increase of reaction pressure. Under the optimized conditions, the catalytic system of hyperbranched PNP/Cr(III)/MAO led to catalytic activity of 2.68 × 10⁵ g/(mol Cr·h) and 37.71% selectivity for C₆ and C₈.     

Polymerization of n-Octylallene with Rare Earth Catalyst Composed of Ln(P204)3/Al(i-Bu)3

Polymerization of n‐octylallene was successfully carried out using a conventional binary rare earth catalytic system composed of rare earth tris(2‐ethylhexylphosphonate) (Ln(P₂₀₄)₃) and tri‐isobutyl aluminum (Al(i‐Bu)₃) for the first time. The effects of catalyst, solvent, reaction time and temperature on the polymerization of n‐octylallene were studied. The resulting poly(n‐octylallene) has weight‐average molecular weight of 11000, molecular weight distribution of 1.4 and 96% yield under the moderate reaction conditions: [Al]/[Y] =50 (molar ratio), [n‐octylallene]/[Y] =100 (molar ratio), polymerized at 80°C for 20 h in bulk. The poly(n‐octylallene) obtained consisted of 1,2‐ and 2,3‐polymerized units, and was characterized by FT‐IR, ¹H NMR and GPC. Further investigation shows that the polymerization of n‐octylallene has some living polymerization characteristics, preparing the polymer with controlled molecular weight and narrower molecular weight distribution.     

27Al NMR diffusometry of Al13 Keggin nanoclusters

Although nanometer-sized aluminum hydroxide clusters (i.e., ϵ-Al₁₃, [Al₁₃O₄(OH)₂₄(H₂O)₁₂]⁷⁺) command a central role in aluminum ion speciation and transformations between minerals, measurement of their translational diffusion is often limited to indirect methods. Here, ²⁷Al pulsed field gradient stimulated echo nuclear magnetic resonance (PFGSTE NMR) spectroscopy has been applied to the AlO₄ core of the ϵ-Al₁₃ cluster with complementary theoretical simulations of the diffusion coefficient and corresponding hydrodynamic radii from a boundary element-based calculation. The tetrahedral AlO₄ center of the ϵ-Al₁₃ cluster is symmetric and exhibits only weak quadrupolar coupling, which results in favorable T₁ and T₂ ²⁷Al NMR relaxation coefficients for ²⁷Al PFGSTE NMR studies. Stokes–Einstein relationship was used to relate the ²⁷Al diffusion coefficient of the ϵ-Al₁₃ cluster to the hydrodynamic radius for comparison with theoretical simulations, dynamic light scattering from literature, and previously published ¹H PFGSTE NMR studies of chelated Keggin clusters. This first-of-its-kind observation proves that ²⁷Al PFGSTE NMR diffusometry can probe symmetric Al environments in polynuclear clusters of greater molecular weight than previously considered.     

Role of the Support in Catalysis: Activation of a Mononuclear Ruthenium Complex for Ethene Dimerization by Chemisorption on Dealuminated Zeolite Y

A set of supported ruthenium complexes with systematically varied ratios of chemisorbed to physisorbed species was formed by contacting cis‐[Ru(acac)₂(C₂H₄)₂] ( I ; acac=C₅H₇O₂^?) with dealuminated zeolite Y. Extended X‐ray absorption fine structure (EXAFS) spectra used to characterize the samples confirmed the systematic variation in the loadings of the two supported species and demonstrated that removal of bidentate acac ligands from I accompanied chemisorption to form [Ru(acac)(C₂H₄)₂]⁺ attached through two Ru? O bonds to the Al sites of the zeolite. A high degree of uniformity in the chemisorbed species was demonstrated by sharp bands in the infrared (IR) spectrum characteristic of ruthenium dicarbonyls that formed when CO reacted with the anchored complex. When the ruthenium loading exceeded 1.0 wt % (Ru/Al≈1:6), the additional adsorbed species were simply physisorbed. Ethene ligands on the chemisorbed species reacted to form butenes when the temperature was raised to approximately 393 K; acac ligands remained bonded to Ru. In contrast, ethene ligands on the physisorbed complex simply desorbed under the same conditions. The chemisorption activated the ruthenium complex and facilitated dimerization of the ethene, which occurred catalytically. IR and EXAFS spectra of the supported samples indicate that 1) Ru centers in the chemisorbed species are more electron deficient than those in the physisorbed species and 2) Ru–ethene bonds in the chemisorbed species are less symmetric than those in the physisorbed species, which implies the presence of a preferred configuration for the catalytic dimerization.     

Synthesis and characterization of phosphorescent cyclometalated iridium complexes containing 2,5‐diphenylpyridine based ligands

A series of phosphorescent cyclometalated iridium complexes with 2,5‐diphenylpyridine‐based ligands has been synthesized and characterized to investigate the effect of the simple ligand modification on photophysics, thermostability and electrochemistry. The complexes have the general structure (C^∧N)₂Ir(acac), where C^∧N is a monoanionic cyclometalating ligand [e.g. 2,5‐diphenylpyridyl (dppy), 2,5‐di(4‐methoxyphenyl)pyridyl (dmoppy), 2,5‐di(4‐ethoxyphenyl)pyridyl (deoppy) and 2,5‐di(4‐ethylphenyl)pyridyl (deppy)]. The absorption, emission, cyclic voltammetry and thermostability of the complexes were systematically investigated. The (dppy)₂Ir(acac) has been characterized using X‐ray crystallography. Calculation on the electronic ground state of (dppy)₂Ir(acac) was carried out using B3LYP density functional theory. The highest occupied molecular orbital (HOMO) level is a mixture of Ir and ligand orbitals, while the lowest occupied molecular orbital (LUMO) is predominantly dppy ligand‐based. Electrochemical studies showed the oxidation potentials of (dmoppy)₂Ir(acac), (deoppy)₂Ir(acac), (deppy)₂Ir(acac) were smaller than that of (ppy)₂Ir(acac), while the oxidation potential of (dppy)₂Ir(acac) was larger relative to (ppy)₂Ir(acac). The 10% weight reduction temperatures of these complexes were above that of (ppy)₂Ir(acac). All complexes exhibited intense green photoluminescence, which has been attributed to MLCT triplet emission. The maximum emission wavelengths in CH₂Cl₂ at room temperature were in the range 531–544 nm, which is more red‐shifted than that of (ppy)₂Ir(acac). Copyright © 2005 John Wiley & Sons, Ltd.     

A Zeolite‐Supported Molecular Ruthenium Complex with η6‐C6H6 Ligands: Chemistry Elucidated by Using Spectroscopy and Density Functional Theory

An essentially molecular ruthenium–benzene complex anchored at the aluminum sites of dealuminated zeolite Y was formed by treating a zeolite‐supported mononuclear ruthenium complex, [Ru(acac)(η²‐C₂H₄)₂]⁺ (acac=acetylacetonate, C₅H₇O₂^?), with ¹³C₆H₆ at 413 K. IR, ¹³C NMR, and extended X‐ray absorption fine structure (EXAFS) spectra of the sample reveal the replacement of two ethene ligands and one acac ligand in the original complex with one ¹³C₆H₆ ligand and the formation of adsorbed protonated acac (Hacac). The EXAFS results indicate that the supported [Ru(η⁶‐C₆H₆)]²⁺ incorporates an oxygen atom of the support to balance the charge, being bonded to the zeolite through three Ru? O bonds. The supported ruthenium–benzene complex is analogous to complexes with polyoxometalate ligands, consistent with the high structural uniformity of the zeolite‐supported species, which led to good agreement between the spectra and calculations at the density functional theory level. The calculations show that the interaction of the zeolite with the Hacac formed on treatment of the original complex with ¹³C₆H₆ drives the reaction to form the ruthenium–benzene complex.     

Über basische Aluminiumsalze und ihre Lösungen. XI. Vergleichende 27Al-NMR-Untersuchungen am Mineral Zunyit und basischen Aluminium-Salzen mit tridekameren Al-oxo-hydroxo-aquo-Kationen

Basic Aluminium Salts and their Solutions. XI. ²⁷Al-NMR Studies Comparing the Mineral Zunyite and Basic Aluminium Salts of Tridecameric Al-oxo-hydroxo-aquo-Cations Solid-state high resolution ²⁷Al NMR studies of basic aluminum sulphate and the mineral zunyite, both containing tridecameric Al-oxo-hydroxo groups, show different ²⁷Al spectra. While for zunyite both AlO₆ octahedra (0 ppm) and the central AlO₄ tetrahedron (69 ppm) are observed in the spectrum, in the case of the basic aluminum sulphate only the tetrahedrally coordinated Al (59 ppm) is detected by NMR. This behaviour is explained by structural data, which indicate stronger distortions of the AlO₆ octahedra in the case of the basic aluminum sulphate. The increased shielding of the fourcoordinated Al of the basic sulphate is attributed to an increased ionic character of the Al? O bond in this compound.     

Syntheses and Structures of Acetyl‐Acetonato‐Alumo‐Diphenylsilanolates with Magnesium(II), Iron(II), Iron(III), Cobalt(II), and Nickel(II)

Bis(acetylacetonate)alumo‐oxo‐tetraphenyldisiloxane‐metal(II) dihydrates [(acac)₂Al(O–SiPh₂–O–SiPh₂–O)]₂M(H₂O)₂ (M = Mg, Fe, Co, Ni) were obtained from the corresponding acetyl‐acetonate‐dihydrates (acac)₂M(H₂O)₂ by reaction with the alumosiloxane [O–Ph₂Si–O–SiPh₂–O]₄Al₄(OH)₄. These new compounds display two acac ligands at the aluminum atoms as well as disilatrioxy chains linking the two aluminum atoms forming a (Al–O–Si–O–Si–O)₂ cycle (X‐ray structure analyses). Within this cycle the divalent metal ions M²⁺, to which two water molecules in trans positions are linked, are installed in almost planar MO₄ coordination spheres. Using water free (acac)₂Ni a different product forms: both reactants combine in a 2:1 ratio to yield [O–Ph₂Si–O–SiPh₂–O]₄Al₄(OH)₂O(OH₂)Ni₂(acac)₄. Here, three of the acac ligands were transposed to the aluminum atoms. The nickel atoms are in a distorted octahedral coordination mode from oxygen atoms of the ligands. When iron(III)tris(acetylacetonate) reacts with the alumosiloxane [O–Ph₂Si–O–SiPh₂–O]₃Al₂O(OH)Fe₂(acac)₃ was isolated, in which the two iron atoms still display one of the acac ligands. One of the aluminum atoms is in a tetrahedral oxygen environment, whereas the other is in the center of a trigonal bi‐pyramid formed of oxygen atoms either of the siloxane or of acac. The iron atoms have five‐ or sixfold coordination from oxygen atoms of siloxane, acac, hydroxide or oxide.     

Copolymerization of ethylene with acrylonitrile promoted by novel nonmetallocene catalysts with phenoxy‐imine ligands

A series of novel nonmetallocene catalysts with phenoxy‐imine ligands was synthesized by the treatment of phthaldialdehyde, substituted phenol with TiCl₄, ZrCl₄, and YCl₃ in THF. The structures and properties of the catalysts were characterized by ¹H NMR and elemental analysis. These catalysts were used for copolymerization of ethylene with acrylonitrile after activated by methylaluminoxane (MAO). The effects of copolymerization temperature, Al/M (M = Ti, Zr, and Y) ratio in mole, concentrations of catalyst and comonomer on the polymerization behaviors were investigated in detail. These results revealed that these catalysts were favorable for copolymerization of ethylene with acrylonitrile. Cat. 3 was the most favorable one for the copolymerization of ethylene with acrylonitrile, and the catalytic activity was up to 2.19 × 10⁴ g PE/mol.Ti.h under the conditions: polymerization temperature of 50 °C, Al/Ti molar ratio of 300, catalyst concentration of 1.0 × 10^–4 mol/L, and toluene as solvent. The resultant polymer was characterized by FTIR, cross‐polarization magic angle spinning, ¹³C NMR, WAXD, GPC, and DSC. The results confirmed that the obtained copolymer featured high‐weight–average molecular weight, narrow molecular weight distribution about 1.61–1.95, and high‐acrylonitrile incorporation up to 2.29 mol %. Melting temperature of the copolymer depended on the content of acrylonitrile incorporation within the copolymer chain. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Ein neuer Aluminium/Nickel/Oxo‐Cluster: [Ni(acac)OAl(OtBu)2]4

A New Aluminum/Nickel/Oxo‐Cluster: [Ni(acac)OAl(OtBu)₂]₄ When bis(tert‐butoxy)alane (tBu‐O)₂AlH is allowed to react with nickeldiacetylacetonate at elevated temperature a new nickel/aluminum/oxo cluster [Ni(acac)OAl(OtBu)₂]₄ is formed together with aluminum acetylacetonate Al(acac)₃ and some other products. The metal/oxo cluster is isolated by crystallization and structurally fully characterized by X‐ray diffraction analysis. The molecule [Ni(acac)OAl(OtBu)₂]₄ contains an eight membered Al₄O₄ cycle, to which eight mutually edge sharing NiO₂Al cycles are fused. The overall point symmetry of the metal/oxo cluster is almost S₄. While the aluminum atoms are tetrahedrally surrounded by oxygen ligands (mean distances Al‐O in‐between 1, 730(6) and 1, 789(6) Å)), the nickel atoms are in a square pyramidal coordination sphere of oxygen atoms (Ni‐O_axial = 1.938(6) Å, Ni‐O_basal = 2.056(9) Å; all polyhedra are distorted). The nickel atoms have a d⁸ high spin electron configuration (μ_eff = 3.32 B.M.).     

Mechanism of Formation of Nanocrystalline ZnO Particles through the Reaction of [Zn(acac)2] with NaOH in EtOH

The mechanism of formation of nanocrystalline ZnO particles from the reaction of zinc acetylacetonate ([Zn(acac)₂]) with 2-equivalent NaOH in boiling EtOH was investigated by characterizing the particles and following the transformation of acac moieties. The reaction was found to proceed via hydrolysis of zinc ethoxide derivatives, followed by dehydration–condensation reactions. High-resolution solid-state CP-MAS¹³C NMR measurements indicate that the ZnO particles are produced through Zn (acac)(OZn)_n(acac) (3). Furthermore, it was suggested that acac⁻ligands play an important role in the generation of nanocrystalline ZnO particles by suppressing the hydrolysis–condensation of Zn(acac)(OZn)_n(acac).     

Novel Complex Catalyst of η3‐(Pentamethylcyclopentadienyl)dimethylaluminum/Titanium(IV) Butoxide (Cp*AlMe2/Ti(OBu)4) for Syndiotactic Polystyrene

A novel metallocene catalyst was prepared from the reaction of (η³‐pentamethylcyclopentadienyl)dimethylaluminum (Cp*AlMe₂) and titanium(IV) n‐butoxide Ti(OBu)₄. The resulting titanocene Cp*Ti(OBu)₃ was combined with methylaluminoxane (MAO)/tri‐iso‐butylaluminum (TIBA) to carry out the syndiotactic polymerization of styrene. The resulting syndiotactic polystyrene (sPS) possesses high syndiotacticity according to ¹³C NMR. Catalytic activity and the molecular weight of the resulting sPSs were discussed in terms of reaction temperature, concentration of MAO, amounts of scavenger TIBA added, and the hydrogen pressure applied during polymerization.     

Polymerization of cyclohexene oxide with Al(acac)3-silanol catalyst supported by zeolite and porous silica

The polymerization of cyclohexene oxide with Al(acac)₃-silanol catalyst supported by zeolite and porous silica has been investigated. Cyclohexene oxide was also polymerized to a lesser extent by a zeolite-silanol catalyst and an Al(acac)₃-silica gel catalyst. The catalytic activity of the zeolite-silanol system varied with the zeolite pore size. The catalytic activity of the Al(acac)₃-silanol system was enhanced by supporting the catalyst with porous silica or zeolite. The Al(acac)₃-silanol catalyst supported by zeolite was especially effective in increasing polymer conversion and molecular weight. Catalytic activity increased with increasing chemical interaction between silanol and porous silica. The molecular weight of the polymers with these catalysts increased in the order zeolite-silanol> zeolite-Al(acac)₃-silanol >Al(acac)₃-silanol ≈ Al(acac)₃-silanol supported by porous silica>Al(acac)₃-silica gel.     

Ring‐opening metathesis polymerization of cyclododecene using an electrochemically reduced tungsten‐based catalyst

The ring‐opening metathesis polymerization of cyclododecene using an electrochemically reduced tungsten‐based catalyst (WCl₆? e^?? Al? CH₂Cl₂) is described. In addition, the influence of reaction conditions on the polymerization yield was determined. The resulting polymer has been characterized by NMR, IR, gel permeation chromatography and differential scanning calorimetry. The glass transition temperature and melting point of the polydodecenamer are 19.6°C and 70.0°C respectively. Furthermore, cyclododecene has been polymerized into a low‐molecular‐weight polymer (12.0 × 10³) with a polydispersity of 2.06 in high yields (94%). IR and NMR analysis indicate that the polydodecenamer has a high trans content (60%). Copyright © 2004 John Wiley & Sons, Ltd.     

Coordination Chemistry of [Co(acac)2] with N‐Doped Graphene: Implications for Oxygen Reduction Reaction Reactivity of Organometallic Co‐O4‐N Species

Hybridization of organometallic complexes with graphene‐based materials can give rise to enhanced catalytic performance. Understanding the chemical structures within hybrid materials is of primary importance. In this work, archetypical hybrid materials are synthesized by the reaction of an organometallic complex, [Co^II(acac)₂] (acac=acetylacetonate), with N‐doped graphene‐based materials at room temperature. Experimental characterization of the hybrid materials and theoretical calculations reveal that the organometallic cobalt‐containing species is coordinated to heterocyclic groups in N‐doped graphene as well as to its parental acac ligands. The hybrid material shows high electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline media, and superior durability and methanol tolerance to a Pt/C catalyst. Based on the chemical structures and ORR experiments, the catalytically active species is identified as a Co‐O₄‐N structure.