David Antonelli

University of Sussex, Brighton, England, United Kingdom

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Publications (49)319.11 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: We developed mesoporous and nanostructured TiO2 anodes with very high specific surface, up to more than 500 m2 g−1, that show good promise for lithium battery applications. Modifying the surfactant to form a carbon coating inside the pores at low temperature shows better promises than normal carbonization processes, since the high temperature needed is too high and results in the crystal formation and the loss of porosity.
    Journal of Power Sources 03/2012; 202:357–363. DOI:10.1016/j.jpowsour.2011.11.029 · 6.22 Impact Factor
  • Chaoyang Yue · Michel L Trudeau · David Antonelli
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    ABSTRACT: Mesoporous tantalum oxide, Fe3+-doped mesoporous tantalum oxide, and bis(toluene) titanium reduced mesoporous tantalum oxide were used for the first time as Schrauzer-type photocatalysts for the conversion of dinitrogen to ammonia. The materials were characterized by XRD, TEM, XPS, and nitrogen absorption before and after catalytic runs. The results showed low to moderate activities depending on the composition. In contrast to previously studied Ti catalysts, Fe doping and heat pretreatment were not prerequisites for photocatalytic activity, but did improve the turnover rates by up to a factor of two. The optimal Fe loading for the tantalum oxides was found to be 1 wt% and the optimal heating condition at 300 °C for 3 h. Increased surface area and heat treatment were also found to improve activities. Contrary to our expectations, reduction of the mesostructure with bis(toluene) titanium had little effect on the catalytic activity. In spite of the dramatically higher surface areas of the mesoporous tantalum oxides as compared with bulk titanias used previously in this process, the overall catalytic activities were still less than those obtained in the Schrauzer system. This suggests that the increase in diffusion and surface area offered by the mesoporous structure is offset by the smaller crystalline domain sizes in the walls of the structure, leading to poor electron-hole separation and a reduction in catalytic efficiency. Key words: mesoporous, Schrauzer, ammonia, photocatalysis, tantalum oxide.
    Canadian Journal of Chemistry 02/2011; 83(4):308-314. DOI:10.1139/v05-018 · 1.01 Impact Factor
  • Source
    B O Skadtchenko · D M Antonelli
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    ABSTRACT: The flexible oxidation states of mesoporous Nb, Ta, and Ti oxides make them unique amongst porous materials allowing reaction pathways and cascades that are not possible for mesoporous silica or microporous materials such as zeolites. This electronic activity coupled with the 20–30 Å pores and the amorphous wall structure, which provides greater bandwidth (W) and hence an even greater range of redox potentials, leads to a rich variety of host–guest inclusion chemistry, which serves as an unprecedented 1-D analogue to layered 2-D host–guest inclusion reactions studied for decades. In this paper we survey a series of reactions between these mesoporous hosts and a wide variety of organic and organometallic guest species including alkali fullerides, cobaltocene, and other organometallic sandwhich species, and discuss the electronic and magnetic properties of the resulting composites.Key words: mesoporous materials, semiconductors, fullerides, superconductors, oxides, nanomaterials, metallocenes.
    Canadian Journal of Chemistry 02/2011; 84(3):371-383. DOI:10.1139/v06-021 · 1.01 Impact Factor
  • ChemInform 11/2010; 33(45). DOI:10.1002/chin.200245010
  • M. Vettraino · B. Ye · X. He · D. M. Antonelli
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    ABSTRACT: Manuscript received: 9 October 2000.
    ChemInform 10/2010; 32(42). DOI:10.1002/chin.200142258
  • D. M. ANTONELLI · A. NAKAHIRA · J. Y. YING
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 08/2010; 27(35). DOI:10.1002/chin.199635250
  • Xun He · David Antonelli
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    ABSTRACT: Work in mesoporous silica-based materials began in the early 1990s with work by Mobil. These materials had pore sizes from 20-500 A and surface areas of up to 1500 m(2) g(-1) and were synthesized by a novel liquid crystal templating approach. Researchers subsequently extended this strategy to the synthesis of mesoporous transition metal oxides, a class of materials useful in catalysis, electronic, and magnetic applications because of variable oxidation states, and populated d-bands-features not found in silicates. These materials are already showing promise in electronic and optical applications hinging on the semiconducting properties of transition metal oxides and their potential to act as electron acceptors, an important feature in the design of cathodic materials. This is the first general review of non-silicate mesoporous materials and will focus on recent advances in this area, emphasizing materials possessing unique electronic, magnetic, or optical properties. Also covered are advances in the synthesis and applications of mesostructured sulfides as well as a new class of template-synthesized platinum-based materials that show promise in heterogeneous catalysis.
    Angewandte Chemie International Edition 04/2010; 41(2):215-29. DOI:10.1002/1521-3773(20020118)41:2<214::AID-ANIE214>3.0.CO;2-D · 11.26 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hexagonally packed mesoporous silica (HMS) grafted with titanium, vanadium, and chromium organometallic fragments possessing metal oxidation states between (II) and (IV) were synthesized and characterized by XRD, nitrogen adsorption, XPS, and elemental analysis. These materials were then tested for their excess hydrogen storage capacity, with the purpose in mind of subtracting out the physisorption component and establishing which transition metal fragments and oxidation states functioned as the most effective binding sites for hydrogen. By varying the metal type and the metal oxidation state, as well as the ligand environment by exchanging the alkyl group with hydride via hydrogenolysis, the effects of these variations on the H2 adsorption capacity of the metal center as well as on the binding enthalpies of these systems were investigated. This study demonstrated that titanium is more effective at hydrogen binding than vanadium and chromium. Hence, HMS silica grafted with benzyl titanium(III) fragments can accommodate up to 4.85 H2 per Ti center and 4.74 H2 per Ti center in the case of HMS grafted with bis(naphthalene) titanium. This compares to 2.74 H2 per vanadium center in the case of HMS grafted with tris(mesityl) vanadium, and to 1.82 H2 and 2.20 H2 per chromium center as in the HMS treated with tris[bis(trimethylsilyl)methyl] chromium and bis[(trimethylsilyl)methyl] chromium, respectively. The hydrogenation of the metal centers had no effect on the adsorption capacity of the titanium centers and only a slight effect on the vanadium centers; however, a far more pronounced effect was observed in the case of chromium as the adsorption capacity increased from 1.82 H2 to 3.2 H2 per chromium in the case of HMS treated with tris[bis(trimethylsilyl)methyl] chromium, and from 2.20 H2 to 3.5 H2 per chromium in the case of HMS treated with bis[(trimethylsilyl)methyl] chromium. The differences in binding capacity and the effect of hydrogenation were attributed to ligand environment, the availability of open binding sites, and the ability of the metal center to back-bond to the antibonding orbital of the chemisorbed H2 ligands.
    The Journal of Physical Chemistry C 04/2010; 114(18). DOI:10.1021/jp1013048 · 4.77 Impact Factor
  • D. M. ANTONELLI · J. Y. YING
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 02/2010; 28(7). DOI:10.1002/chin.199707326
  • Jason Simmons · Taner Yildirim · Ahmad Hamaed · David Antonelli
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    ABSTRACT: The optimum conditions for viable room temperature hydrogen storage require materials that possess isoteric heats of adsorption in between that of standard physisorbers and chemisorbers, typically in the ˜20-30 kJ/mol regime. It has been theoretically predicted that transition metal atoms incorporated onto high surface area materials could enable significant room temperature storage; herein we demonstrate a possible experimental proof of these predictions. Titanium(III) complexes are grafted onto porous silica hosts, then activated to generate sites for dissociative adsorption of hydrogen gas. Using a combination of sorption measurements and inelastic neutron scattering, we show that the activated titanium provides strong hydrogen binding sites at room temperature and that adsorbed hydrogen is stable for long periods of time at ambient conditions. Further, the hydrogen can be desorbed under mild processing conditions. Neutron vibrational spectra agree well with theoretically predicted vibrational modes of the Ti---H complex. These results represent an important step towards reversible room temperature hydrogen storage.
  • Yuxiang Rao · Junjie Kang · David Antonelli
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    ABSTRACT: The isomerization of 1-hexene at 343 K was conducted over, a series of sulfated mesoporous Ta oxides with pore sizes ranging from 12 to 30 A. The results were compared to the popular industrial catalysis HY-zeolite, H-ZSMS, and Ambertyst 15. The conversion of 1-hexane to transcist-2-isomers can reach 95.89% in 4 h, which is roughly 2 times faster than Ambertyst 15 and 20 times faster than HY-zeolite and H-ZSM5. GC analysis confirmed that trans- and cis-2-hexane isomers formed through a double bond shift process as the only two principal products. The molar ratio of translcis-2-hexene isomers varies with pore size, clearly showing confinement effects in this process. The selectivity or our best material toward the trans-isomer is at least 3 times greater than that of either zeolite or Amberyst 15. The best catalytic results in this study were achieved when using C-12 H2SO4 mesoporous Ta oxide, which possesses apK(a) of -8.2 and 19.8 mmol/g acid sites. The X-ray diffraction pattern showed complete retention of the mesostructure throughout catalysis as evidenced by a single brand reflection. Pyridine adsorption and infrared spectroscopy (IR) suggest that both Bronsted sites (similar to 1538 cm(-1)) and Lewis sites (similar to 1443 cm(-1)) coexist on the surface of these materials. The large amount of Bronsted acid sites, high BET surface areas, high acid strength Ho, and superior diffusion properties of C12H2SO4 mesoporous To oxide are probably responsible for its extremely high catalytic activity and selectivity.
    Journal of the American Chemical Society 02/2008; 130(2):394-5. DOI:10.1021/ja076584n · 11.44 Impact Factor
  • Chaoyang Yue · Longhui Qiu · Michel Trudeau · David Antonelli
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    ABSTRACT: A series of early metal-promoted Ru-, Pd-, Pt-, and Rh-doped mesoporous tantalum oxide catalysts were synthesized using a variety of dopant ratios and dopant precursors, and the effects of these parameters on the catalytic activity of NH3 synthesis from H2 and N2 were explored. Previous studies on this system supported an unprecedented mechanism in which N-N cleavage occurred at the Ta sites rather than on Ru. The results of the present study showed, for all systems, that Ba is a better promoter than Cs or La and that the nitrate is a superior precursor for Ba than the isopropoxide or the hydroxide. 15N-labeling studies showed that residual nitrate functions as the major ammonia source in the first hour but that it does not account for the ammonia produced after the nitrate is completely consumed. Ru3(CO)12 proved to be a better Ru precursor than RuCl(3).3H2O, and an almost linear increase in activity with increasing Ru loading level was observed at 350 degrees C (623 K). However, at 175 degrees C (448 K), the increase in Ru had no effect on the reaction rate. Pd functioned with comparable rates to Ru, while Pt and Rh functioned far less efficiently. The surprising activities for the Pd-doped catalysts, coupled with XPS evidence for low-valent Ta in this catalyst system, support a mechanism in which cleavage of the N-N triple bond occurs on Ta rather than the precious metal because the Ea value for N-N cleavage on Pd is 2.5 times greater than that for Ru, and the 9.3 kJ mol-1 Ea value measured previously for the Ru system suggests that N-N cleavage cannot occur at the Ru surface.
    Inorganic Chemistry 07/2007; 46(12):5084-92. DOI:10.1021/ic062385d · 4.79 Impact Factor
  • Yuxiang Rao · Michel Trudeau · David Antonelli
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    ABSTRACT: Materials possessing the high acidities of sulfated zirconia and the diffusion properties of mesoporous oxides are predicted to have numerous applications in the petrochemical industry. Because of surface deactivation and loss of structure under highly acidic conditions, there are few examples of materials which meet these specifications. In this work, mesoporous Nb oxide was treated with 1 M sulfuric acid or phosphoric acid and evaluated for their catalytic activities in the benzylation of toluene or anisole with benzyl alcohol. Characterization by XRD, nitrogen adsorption/desorption, and TEM demonstrated that the mesostructure was surprisingly stable to acid treatment. Pyridine adsorption and infrared spectroscopy (IR) showed a mixture of Lewis and Bronsted sites before and after acid treatment. Titration with a series of indicators demonstrated that sulfated mesoporous Nb oxide possesses a pKa of -8.2 and 31.784 mmol/g acid sites, roughly 100 times stronger than either bulk phosphated or sulfated niobia, which both possess pKa values in the range of -3.0. The best catalytic results in this study were achieved when using mesoporous Nb oxide treated with sulfuric acid; the conversion of benzyl alcohol with anisole to the benzylation product was 100% in 30 min, which is 200 times faster than the bulk catalyst. The extremely high activity was rationalized by the high number of strong Brønsted sites on the surface coupled with the superior diffusion properties of the mesoporous system.
    Journal of the American Chemical Society 12/2006; 128(43):13996-7. DOI:10.1021/ja0647147 · 11.44 Impact Factor
  • B. O. Skadtchenko · D. M. Antonelli
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    ABSTRACT: The flexible oxidation states of mesoporous Nb, Ta, and Ti oxides make them unique amongst porous materials allowing reaction pathways and cascades that are not possible for mesoporous silica or microporous materials such as zeolites. This electronic activity coupled with the 20-30 angstrom pores and the amorphous wall structure, which provides greater bandwidth (W) and hence an even greater range of redox potentials, leads to a rich variety of host-guest inclusion chemistry, which serves as an unprecedented 1-D analogue to layered 2-D host-guest inclusion reactions studied for decades. In this paper we survey a series of reactions between these mesoporous hosts and a wide variety of organic and organometallic guest species including alkali fullerides, cobaltocene, and other organometallic sandwhich species, and discuss the electronic and magnetic properties of the resulting composites.
    ChemInform 08/2006; 37(35). DOI:10.1002/chin.200635245
  • Chaoyang Yue · Michel Trudeau · David Antonelli
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    ABSTRACT: A new mesoporous Ta oxide catalyst for conversion of dinitrogen to ammonia shows strong evidence for a novel mechanism involving low valent Ta on the surface, supporting recent work in organometallic chemistry using low valent early transition metals for dinitrogen cleavage.
    Chemical Communications 06/2006; 37(18):1918-20. DOI:10.1039/b517415e · 6.83 Impact Factor
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    ABSTRACT: A mesoporous tantalum oxide lithium fulleride composite was synthesized by solution intercalation of C60 into a prefabricated Li-TaTMS material and characterized by elemental analysis, X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption−desorption, X-ray photoelectron spectroscopy (XPS), superconducting quantum interference device (SQUID) magnetometry, and solid-state 13C and 7Li NMR. The room conductivity measurements of Li fulleride material showed that this material was insulating, as opposed to previously synthesized K and Na based mesoporous Ta oxide fulleride composites with similar composition, which were semiconducting or metallic. Solid-state 7Li NMR of this lithium composite exhibited a single Li environment. XPS measurements indicated an oxidation of the tantalum oxide walls had occurred upon intercalation of the fullerene 13C NMR, and Raman measurements were consistent with one fulleride species in the pores. Electrochemical measurements revealed largely irreversible behavior upon intercalation/deintercalation of Li+ into this material. This was attributed to the insulating nature of this composite impeding charge transport through the channels. In contrast, the corresponding Na fulleride intercalate showed reversible Li insertion, possibly due to enhanced charge transport through the semiconducting structure.
    Chemistry of Materials 07/2004; 16(15). DOI:10.1021/cm030548f · 8.54 Impact Factor
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    ABSTRACT: The synthesis and properties of sulfate- and phosphate-free mesostructured iron oxide prepared using a chelating triol surfactant are reported. Materials synthesized using metal−surfactant ratios of 1:1, 2:1, 3:1, and 4:1 all showed a broad single reflection in the XRD at low angle corresponding to a wormhole mesostructure, as well as small higher angle peaks consistent with the presence of a small amount of maghemite and hemitite. TEM images confirmed the wormhole structure of the mesophase, while also revealing rodlike crystals corresponding to one or both of the two known phases of iron oxide observed in the XRD. Attempts to remove the surfactant by washing or chemical treatment were unsuccessful. Calcination led to a complete collapse of the structure and crystallization of the mesophase into maghemite. Magnetic studies provided evidence for the formation of superparamagnetic iron oxide particles within the walls of the mesostructure in addition to a small magnetic contribution arising from the presence of larger maghemite crystallites, while the calcined materials behaved more like a soft ferromagnet.
    The Journal of Physical Chemistry B 04/2004; 108(17). DOI:10.1021/jp031259h · 3.30 Impact Factor
  • Andrei Lezau · Boris Skadtchenko · Michel Trudeau · David Antonelli
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    ABSTRACT: Mesoporous Ta oxide with a pore size of ca. 22 Å and a BET surface area of 486 m2 g−1 was reduced by bis(toluene)Ti in the presence of dinitrogen and the product characterized by XPS, XRD, elemental analysis, nitrogen absorption, and variable temperature conductivity measurements. The XPS spectrum shows three different Ti species on the surface, in addition to a strong emission for a reduced nitrogen species and ammonia. There is also evidence for slight reduction of the Ta oxide mesostructure, consistent with the framework acting as an oxidizing agent. The conductivity measurements show a gradual increase in resistance with decreasing temperature, consistent with a semiconductor. In general the nitrogen content ranged from 1.5 to 3%. In order to gain insight into the nature of the cleavage of nitrogen on the reduced surface, the materials were prepared in the absence of nitrogen and then treated with nitrogen at room temperature and pressure for varying lengths of time. Surprisingly, these materials absorbed a maximum of 0.8% N and were almost insulating. This indicates that the initial Ti phase formed on the surface of the mesoporous Ta oxide is highly reactive and that it rapidly quenches itself, most likely through oxidation by the hydrated Ta oxide beneath the surface, before it has a chance to react in a second step with nitrogen. Maximum absorption of nitrogen occurred within the first 2 h, indicating that this reaction is fast. Treatment with excess moisture led to complete conversion of the nitride to ammonia in minutes, indicating that access to moisture is the rate-limiting step of the surface protonation process.
    Dalton Transactions 10/2003; DOI:10.1039/B301134H · 4.20 Impact Factor
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    ABSTRACT: Mesoporous tantalum oxide–sodium fulleride composites were synthesized by solution impregnation and characterized by elemental analysis, X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption–desorption, X-ray electron photoelectron spectroscopy (XPS), superconducting quantum interference device (SQUID) magnetometry, variable-temperature electron transport measurements, and solid-state 13C and 23Na NMR spectroscopy. The room temperature conductivity pattern as a function of sodium reduction level displayed a minimum at n = 3.0 and a maximum at n = 4.5, where n is the formal charge on the fulleride. The variable-temperature conductivity measurements demonstrated that the n = 0.5 and n = 4.5 materials were semiconductors. Solid-state 23Na NMR spectroscopy of the n = 0.5 composite exhibited three Na environments in the composites: two associated with the tantalum oxide walls and a third associated with the fulleride. The n = 3.0 and n = 4.5 materials showed a large build-up of Na ions in the wall with no visible Na resonances associated with the fulleride, suggesting a structure in which the fulleride units exist as naked anions in one-dimensional chains surrounded first by a layer of Na ions and then by a layer of mesoporous tantalum oxide. Solid-state 13C NMR experiments showed more than one fulleride species in both the n = 0.5 and the n = 4.5 composites, as well as pure C60 in the n = 0.5 material, but almost exclusively C603– in the n = 3.0 material. The retention of carbon throughout reduction suggests that polymerization may have occurred, however this could not be verified by 13C NMR spectroscopy, because the region where sp3 fullerene resonances normally appear was obscured by solvent peaks.
    Advanced Functional Materials 09/2003; 13(9):671 - 681. DOI:10.1002/adfm.200304392 · 11.81 Impact Factor
  • Xun He · Andy Y H Lo · Michel Trudeau · Robert W Schurko · David Antonelli
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    ABSTRACT: New mesoporous niobium oxides with 5, 10, and 15 mol% vanadium(V) doped into the walls of the structure were synthesized by the ligand-assisted templating method with an octadecylamine template. These materials were characterized by XRD, XPS, EPR, elemental analysis, and nitrogen adsorption before being treated with excess bis(benzene)chromium to give new composites with an organometallic phase in the walls. All materials were also characterized by EPR, XRD, nitrogen adsorption, XPS, SQUID magnetometry, and elemental analysis. The materials with higher percentages of vanadium absorbed more bis(benzene)chromium, because this process depends largely on the electron transfer between the organometallic and the walls of the mesostructure and vanadium(V) is a stronger oxidant than niobium(V). Conductivity studies on these materials revealed that the ratio of Cr(0) to Cr(l) in the pores was more important than the absolute Cr loading level in governing electron transport properties but that increasing the V content led to more insulating behavior regardless of the Cr concentration. Solid-state 2H NMR studies on perdeuteriobenzene analogues of these composites showed the presence of the neutral and cationic Cr species in different ratios depending on the loading. Tumbling of these species was also slow on the NMR time scale, indicating that the charge-carrying Cr species are not rapidly moving through the pore channels of the mesostructure. This suggests that the walls of the structure may play a key role in charge transfer in these composites, contrary to what was previously believed.
    Inorganic Chemistry 02/2003; 42(2):335-47. DOI:10.1021/ic020559v · 4.79 Impact Factor

Publication Stats

2k Citations
319.11 Total Impact Points

Institutions

  • 1996–2010
    • University of Sussex
      Brighton, England, United Kingdom
  • 1995–2010
    • Massachusetts Institute of Technology
      • Department of Chemical Engineering
      Cambridge, Massachusetts, United States
  • 1999–2008
    • University of Windsor
      • Department of Chemistry and Biochemistry
      Windsor, Ontario, Canada