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Decomposition of lithium amide and lithium imide with and without anion promoter / Junqing Zhang in Industrial & engineering chemistry research, Vol. 50 N° 13 (Juillet 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 13 (Juillet 2011) . - pp. 8058-8064 Titre : Decomposition of lithium amide and lithium imide with and without anion promoter Type de document : texte imprimé Auteurs : Junqing Zhang, Auteur ; Yun Hang Hu, Auteur Année de publication : 2011 Article en page(s) : pp. 8058-8064 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Promoter Résumé : The decompositions of lithium amide (LiNH2) and lithium imide (Li2NH) are important steps for hydrogen storage in Li3N. Herein, the decompositions of LiNH2 and Li2NH with and without anion promoter were investigated by using temperature-programmed decomposition (TPD) and X-ray diffraction (XRD) techniques. It was found that the decomposition of LiNH2 produced Li2NH and NH3 via two steps in the temperature range of 300—450 °C: LiNH2 into a stable intermediate species (Li1.5NH1.5) and then into Li2NH. Furthermore, Li2NH is decomposed into Li, H2, and N2 without formation of Li3N in the temperature range of 550-750 °C. The decompositions of LiNH2 and Li2NH can be promoted by chloride ion (Cl-). The introduction of Cl- into LiNH2 resulted in the generation of a new NH3 peak at low temperature of 250 °C besides the original NH3 peak at 330 °C in its TPD profiles. Furthermore, Cl- can decrease the decomposition temperature of Li2NH by about 110 °C. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24332131 [article] Decomposition of lithium amide and lithium imide with and without anion promoter [texte imprimé] / Junqing Zhang, Auteur ; Yun Hang Hu, Auteur . - 2011 . - pp. 8058-8064. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 13 (Juillet 2011) . - pp. 8058-8064 Mots-clés : Promoter Résumé : The decompositions of lithium amide (LiNH2) and lithium imide (Li2NH) are important steps for hydrogen storage in Li3N. Herein, the decompositions of LiNH2 and Li2NH with and without anion promoter were investigated by using temperature-programmed decomposition (TPD) and X-ray diffraction (XRD) techniques. It was found that the decomposition of LiNH2 produced Li2NH and NH3 via two steps in the temperature range of 300—450 °C: LiNH2 into a stable intermediate species (Li1.5NH1.5) and then into Li2NH. Furthermore, Li2NH is decomposed into Li, H2, and N2 without formation of Li3N in the temperature range of 550-750 °C. The decompositions of LiNH2 and Li2NH can be promoted by chloride ion (Cl-). The introduction of Cl- into LiNH2 resulted in the generation of a new NH3 peak at low temperature of 250 °C besides the original NH3 peak at 330 °C in its TPD profiles. Furthermore, Cl- can decrease the decomposition temperature of Li2NH by about 110 °C. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24332131

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

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

Temperature - induced irreversible change of ZnO optical energy gap / Yan Huo in Industrial & engineering chemistry research, Vol. 51 N° 2 (Janvier 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 2 (Janvier 2012) . - pp. 1083-1085 Titre : Temperature - induced irreversible change of ZnO optical energy gap Type de document : texte imprimé Auteurs : Yan Huo, Auteur ; Yun Hang Hu, Auteur Année de publication : 2012 Article en page(s) : pp. 1083-1085 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Optical  energy Résumé : It is generally recognized that the change of ZnO optical properties due to high-temperature treatment is reversible. However, herein, it is reported that high-temperature treatment in air caused an irreversible decrease in ZnO optical energy gap (Eg). The irreversible decrease in Eg was enhanced with increasing treatment temperature. Furthermore, it was found that the irreversible decrease in Eg can be attributed to the enlargement of ZnO crystal particles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25476441 [article] Temperature - induced irreversible change of ZnO optical energy gap [texte imprimé] / Yan Huo, Auteur ; Yun Hang Hu, Auteur . - 2012 . - pp. 1083-1085. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 2 (Janvier 2012) . - pp. 1083-1085 Mots-clés : Optical  energy Résumé : It is generally recognized that the change of ZnO optical properties due to high-temperature treatment is reversible. However, herein, it is reported that high-temperature treatment in air caused an irreversible decrease in ZnO optical energy gap (Eg). The irreversible decrease in Eg was enhanced with increasing treatment temperature. Furthermore, it was found that the irreversible decrease in Eg can be attributed to the enlargement of ZnO crystal particles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25476441