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Effect of oxygen content on structures of graphite oxides / Hui Wang in Industrial & engineering chemistry research, Vol. 50 N° 10 (Mai 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 10 (Mai 2011) . - pp. 6132-6137 Titre : Effect of oxygen content on structures of graphite oxides Type de document : texte imprimé Auteurs : Hui Wang, Auteur ; Yun Hang Hu, Auteur Année de publication : 2011 Article en page(s) : pp. 6132-6137 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Oxygen  content Résumé : Graphite oxide was synthesized by the oxidation of graphite via a modified Hummers approach. The oxygen content of graphite oxide was tuned by changing the oxidation time. The saturated ratio of oxygen to carbon is 0.47. Furthermore, the effect of oxygen content on the structures of graphite oxide was evaluated by using SEM, TEM, XRD, Raman, FTIR, TG, TPD-MS, and nitrogen adsorption. It was found that the types of functional groups in graphite oxides, which are epoxy, hydroxyl, and carboxyl groups, were independent of oxygen content. However, the interplanar space and BET surface area of graphite oxide linearly increased with increasing O/C ratio. Furthermore, the structure of graphite can be easily and remarkably disordered even by partial oxidation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24158912 [article] Effect of oxygen content on structures of graphite oxides [texte imprimé] / Hui Wang, Auteur ; Yun Hang Hu, Auteur . - 2011 . - pp. 6132-6137. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 10 (Mai 2011) . - pp. 6132-6137 Mots-clés : Oxygen  content Résumé : Graphite oxide was synthesized by the oxidation of graphite via a modified Hummers approach. The oxygen content of graphite oxide was tuned by changing the oxidation time. The saturated ratio of oxygen to carbon is 0.47. Furthermore, the effect of oxygen content on the structures of graphite oxide was evaluated by using SEM, TEM, XRD, Raman, FTIR, TG, TPD-MS, and nitrogen adsorption. It was found that the types of functional groups in graphite oxides, which are epoxy, hydroxyl, and carboxyl groups, were independent of oxygen content. However, the interplanar space and BET surface area of graphite oxide linearly increased with increasing O/C ratio. Furthermore, the structure of graphite can be easily and remarkably disordered even by partial oxidation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24158912

Facile sodium alginate assisted assembly of ni−al layered double hydroxide nanostructures / Hui Wang in Industrial & engineering chemistry research, Vol. 49 N° 6 (Mars 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2759–2767 Titre : Facile sodium alginate assisted assembly of ni−al layered double hydroxide nanostructures Type de document : texte imprimé Auteurs : Hui Wang, Auteur ; Guoli Fan, Auteur ; Chen Zheng, Auteur Année de publication : 2010 Article en page(s) : pp. 2759–2767 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Facile;  Sodium;  Alginate;  Assembly;  Layered;  Double;  Hydroxide;  Nanostructures Résumé : Self-assembled three-dimensional Ni−Al layered double hydroxide (LDH) nanostructures have been successfully synthesized using a facile biopolymer-assisted approach in the presence of a simple, safe, and inexpensive sodium alginate biopolymer under hydrothermal conditions. The structure and morphology of LDH nanostructures obtained have been investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), and UV−visible diffuse spectroscopy (UV−vis). Three types of pompon-like, marigold-like, and coral-like LDH nanostructures could be obtained by adjusting the synthesis parameters including hydrothermal aging time, concentration of metal ions, and reaction temperature. A possible formation mechanism for the controlled organization of primary LDH nanosheet building units into special three-dimensional nanostructures is proposed on the basis of the interaction between sodium alginate molecules and LDH crystals. Furthermore, after calcination of LDHs at 500 and 700 °C, the resulting NiO-based mixed metal oxides still maintain the three-dimensional morphology of their LDH precursors to some extent, indicative of the high thermal stability of nanostructures. The findings in this work provide a feasible approach for the morphosynthesis of LDH nanomaterials with special superstructures. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901519h [article] Facile sodium alginate assisted assembly of ni−al layered double hydroxide nanostructures [texte imprimé] / Hui Wang, Auteur ; Guoli Fan, Auteur ; Chen Zheng, Auteur . - 2010 . - pp. 2759–2767. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2759–2767 Mots-clés : Facile;  Sodium;  Alginate;  Assembly;  Layered;  Double;  Hydroxide;  Nanostructures Résumé : Self-assembled three-dimensional Ni−Al layered double hydroxide (LDH) nanostructures have been successfully synthesized using a facile biopolymer-assisted approach in the presence of a simple, safe, and inexpensive sodium alginate biopolymer under hydrothermal conditions. The structure and morphology of LDH nanostructures obtained have been investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), and UV−visible diffuse spectroscopy (UV−vis). Three types of pompon-like, marigold-like, and coral-like LDH nanostructures could be obtained by adjusting the synthesis parameters including hydrothermal aging time, concentration of metal ions, and reaction temperature. A possible formation mechanism for the controlled organization of primary LDH nanosheet building units into special three-dimensional nanostructures is proposed on the basis of the interaction between sodium alginate molecules and LDH crystals. Furthermore, after calcination of LDHs at 500 and 700 °C, the resulting NiO-based mixed metal oxides still maintain the three-dimensional morphology of their LDH precursors to some extent, indicative of the high thermal stability of nanostructures. The findings in this work provide a feasible approach for the morphosynthesis of LDH nanomaterials with special superstructures. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901519h

Kinetic studies of carbon dioxide reforming of methane over ni−co/al−mg−o bimetallic catalyst / Jianguo Zhang in Industrial & engineering chemistry research, Vol. 48 N°2 (Janvier 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 677–684 Titre : Kinetic studies of carbon dioxide reforming of methane over ni−co/al−mg−o bimetallic catalyst Type de document : texte imprimé Auteurs : Jianguo Zhang, Auteur ; Hui Wang, Auteur ; Ajay Kumar Dalai, Auteur Année de publication : 2009 Article en page(s) : p. 677–684 Note générale : chemical engenireeng Langues : Anglais (eng) Mots-clés : Bimetallic  Catalyst Résumé : The kinetics of CO2 reforming with CH4 over a Ni−Co/Al−Mg−O bimetallic catalyst was investigated in a fixed bed reactor at a temperature range of 650−750 °C and the partial pressures of CO2 and CH4 ranging from 30 to 190 kPa. Owing to the simultaneous occurrence of the CO2 reforming reaction and the reverse water−gas shift reaction (RWGS) in the system, the apparent activation energies with respect to reactant consumption and product formation were found different and they are 69.4 and 25.9 kJ/mol for CH4 and CO2 consumption and 85.1 and 61.8 kJ/mol for H2 and CO formation, respectively. It was also found that the reforming rate in terms of CH4 consumption was less sensitive to CO2 partial pressures but had stronger dependence on CH4 partial pressures. At a constant CH4 partial pressure, the increase in CO2 partial pressure did not cause significant change in the reforming rate, whereas at a constant CO2 partial pressure the reforming rate increased with the increase in CH4 partial pressure. The increase in extra CO2 at a constant CH4 pressure led to decreases in hydrogen (H2) formation but increase in carbon monoxide (CO) formation due to the simultaneous occurrence of the reverse water-gas shift reaction. A Langmuir−Hinshelwood (L–H) model was also developed assuming that the dissociation of CH4 and the reaction between the carbon species and the activated carbon dioxide are the rate determining steps over the Ni–Co/Al–Mg–O. It satisfactorily fits the experimental data as well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801078p [article] Kinetic studies of carbon dioxide reforming of methane over ni−co/al−mg−o bimetallic catalyst [texte imprimé] / Jianguo Zhang, Auteur ; Hui Wang, Auteur ; Ajay Kumar Dalai, Auteur . - 2009 . - p. 677–684. chemical engenireeng Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 677–684 Mots-clés : Bimetallic  Catalyst Résumé : The kinetics of CO2 reforming with CH4 over a Ni−Co/Al−Mg−O bimetallic catalyst was investigated in a fixed bed reactor at a temperature range of 650−750 °C and the partial pressures of CO2 and CH4 ranging from 30 to 190 kPa. Owing to the simultaneous occurrence of the CO2 reforming reaction and the reverse water−gas shift reaction (RWGS) in the system, the apparent activation energies with respect to reactant consumption and product formation were found different and they are 69.4 and 25.9 kJ/mol for CH4 and CO2 consumption and 85.1 and 61.8 kJ/mol for H2 and CO formation, respectively. It was also found that the reforming rate in terms of CH4 consumption was less sensitive to CO2 partial pressures but had stronger dependence on CH4 partial pressures. At a constant CH4 partial pressure, the increase in CO2 partial pressure did not cause significant change in the reforming rate, whereas at a constant CO2 partial pressure the reforming rate increased with the increase in CH4 partial pressure. The increase in extra CO2 at a constant CH4 pressure led to decreases in hydrogen (H2) formation but increase in carbon monoxide (CO) formation due to the simultaneous occurrence of the reverse water-gas shift reaction. A Langmuir−Hinshelwood (L–H) model was also developed assuming that the dissociation of CH4 and the reaction between the carbon species and the activated carbon dioxide are the rate determining steps over the Ni–Co/Al–Mg–O. It satisfactorily fits the experimental data as well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801078p

Partial slip contact analysis on three-dimensional elastic layered half space / Zhan-jiang Wang in Transactions of the ASME . Journal of tribology, Vol. 132 N° 2 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 132 N° 2 (Avril 2010) . - 12 p. Titre : Partial slip contact analysis on three-dimensional elastic layered half space Type de document : texte imprimé Auteurs : Zhan-jiang Wang, Auteur ; Wen-Zhong Wang, Auteur ; Hui Wang, Auteur Année de publication : 2011 Article en page(s) : 12 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Compressibility  Conjugate  gradient  methods  Elastic  constants  Elasticity  Fast  Fourier  transforms  Internal  stresses  Mechanical  contact  Slip Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An elastic contact model for three-dimensional layered or coated materials under coupled normal and tangential loads, with consideration of partial slip effects, has been developed in this paper. The response functions for calculating the displacements and stresses were determined in the frequency domain by using the Papkovich–Neuber potentials. The partial slip contact problem was solved by a numerical procedure based on the conjugate Gradient method and fast Fourier transform technique. The contact pressure, surface shear tractions, stick ratios, rigid body displacements, and subsurface stresses are analyzed under different conditions with variations in the material properties and coating thickness. Results show that stiffer coatings tend to decrease the stick ratios and the rigid ball tangential displacements in comparison to those with compliant coatings under the same contact conditions. For stiffer coatings, the values of the von Mises stress and compressive surface stress increase and the positions of maximum von Mises stress move up to the surface; meanwhile, the distributions of the compressive stress become asymmetric due to the action of the tangential load. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Partial slip contact analysis on three-dimensional elastic layered half space [texte imprimé] / Zhan-jiang Wang, Auteur ; Wen-Zhong Wang, Auteur ; Hui Wang, Auteur . - 2011 . - 12 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 132 N° 2 (Avril 2010) . - 12 p. Mots-clés : Compressibility  Conjugate  gradient  methods  Elastic  constants  Elasticity  Fast  Fourier  transforms  Internal  stresses  Mechanical  contact  Slip Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An elastic contact model for three-dimensional layered or coated materials under coupled normal and tangential loads, with consideration of partial slip effects, has been developed in this paper. The response functions for calculating the displacements and stresses were determined in the frequency domain by using the Papkovich–Neuber potentials. The partial slip contact problem was solved by a numerical procedure based on the conjugate Gradient method and fast Fourier transform technique. The contact pressure, surface shear tractions, stick ratios, rigid body displacements, and subsurface stresses are analyzed under different conditions with variations in the material properties and coating thickness. Results show that stiffer coatings tend to decrease the stick ratios and the rigid ball tangential displacements in comparison to those with compliant coatings under the same contact conditions. For stiffer coatings, the values of the von Mises stress and compressive surface stress increase and the positions of maximum von Mises stress move up to the surface; meanwhile, the distributions of the compressive stress become asymmetric due to the action of the tangential load. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...]

Promoting effect of graphene on dye - sensitized solar cells / Hui Wang in Industrial & engineering chemistry research, Vol. 51 N° 32 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 32 (Août 2012) . - pp. 10613-10620 Titre : Promoting effect of graphene on dye - sensitized solar cells Type de document : texte imprimé Auteurs : Hui Wang, Auteur ; Samantha L Leonard, Auteur ; Yun Hang Hu, Auteur Année de publication : 2012 Article en page(s) : pp. 10613-10620 Langues : Anglais (eng) Mots-clés : Dyes Résumé : In this paper, a simple approach without a prereduction of graphene oxide was exploited to prepare a graphene-doped TiO2 film for dye-sensitized solar cells (DSSCs). The performance measurement of the DSSCs showed that the incorporation of graphene could increase the short-circuit current density and power conversion efficiency by 52.4 and 55.3%, respectively. Furthermore, it was demonstrated that the performance enhancement was due to the promoting effect of graphene on electron transfer instead of the increase of dye loading in TiO2/graphene composite films. However, graphene can also absorb solar light, which could lead to the decrease of light harvest of dye molecules and thus a negative effect on the power conversion efficiency of DSSCs. Furthermore, graphene might decrease the actual dye loading on TiO2 in a TiO2/graphene film, which can also make a negative contribution to the conversion efficiency. As a result, the promoting effect of graphene is strongly dependent on its content; namely, the efficiency of DSSCs increases to the maximum value and then decreases with increasing graphene content in TiO2/graphene composites. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26259765 [article] Promoting effect of graphene on dye - sensitized solar cells [texte imprimé] / Hui Wang, Auteur ; Samantha L Leonard, Auteur ; Yun Hang Hu, Auteur . - 2012 . - pp. 10613-10620. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 32 (Août 2012) . - pp. 10613-10620 Mots-clés : Dyes Résumé : In this paper, a simple approach without a prereduction of graphene oxide was exploited to prepare a graphene-doped TiO2 film for dye-sensitized solar cells (DSSCs). The performance measurement of the DSSCs showed that the incorporation of graphene could increase the short-circuit current density and power conversion efficiency by 52.4 and 55.3%, respectively. Furthermore, it was demonstrated that the performance enhancement was due to the promoting effect of graphene on electron transfer instead of the increase of dye loading in TiO2/graphene composite films. However, graphene can also absorb solar light, which could lead to the decrease of light harvest of dye molecules and thus a negative effect on the power conversion efficiency of DSSCs. Furthermore, graphene might decrease the actual dye loading on TiO2 in a TiO2/graphene film, which can also make a negative contribution to the conversion efficiency. As a result, the promoting effect of graphene is strongly dependent on its content; namely, the efficiency of DSSCs increases to the maximum value and then decreases with increasing graphene content in TiO2/graphene composites. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26259765

Synthesis, characterization, and catalytic performance of highly dispersed supported nickel catalysts from Ni – Al layered double hydroxides / Jia Wang in Industrial & engineering chemistry research, Vol. 50 N° 24 (Décembre 2011) 

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Visible - light - induced heterostructured Zn – Al – In mixed metal oxide nanocomposite photocatalysts derived from a single precursor / Guoli Fan in Chemical engineering journal, Vol. 174 N° 1 (Octobre 2011) 

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