TiO2 nanotube arrays （TNTs） electrode loaded with Zn nanoparticles was prepared by anodization and the size of Zn nanoparticle loaded on TNTs electrode was controlled by chronoamperometry deposition time. Results of...TiO2 nanotube arrays （TNTs） electrode loaded with Zn nanoparticles was prepared by anodization and the size of Zn nanoparticle loaded on TNTs electrode was controlled by chronoamperometry deposition time. Results of SEM and XRD analysis show that Zn nanoparticles had a diameter of about 15-25 nm when the deposition time was 3-5 s. The UV-Vis diffuse reflectance spectra show the Zn loaded harvest light with 480-780 nm more effectively than the unloaded sample. The photocurrent response of Zn loaded TNTs electrodes were studied, the results showed that TNTs electrodes loaded with Zn nanoparti-cles has 50% increased photocurrent response under high-pressure mercury lamp irradiation compared with unloaded TNTs electrode.展开更多
The effect of a wide variety of metal oxide （MOx） supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under id...The effect of a wide variety of metal oxide （MOx） supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under identical calcination conditions, supported gold catalysts were prepared on a wide variety of MOx supports, and the temperature for 50%conversion was measured to qualita‐tively evaluate the catalytic activities of these simple MOx and supported Au catalysts. Furthermore, the difference in these temperatures for the simple MOx compared to the supported Au catalysts is plotted against the metal–oxygen binding energies of the support MOx. A clear volcano‐like correla‐tion between the temperature difference and the metal–oxygen binding energies is observed. This correlation suggests that the use of MOx with appropriate metal–oxygen binding energies （300–500 kJ/atom O） greatly improves the catalytic activity of MOx by the deposition of Au NPs.展开更多
The meso-Co3O4 and AgxAuyPd/meso-Co3O4 catalysts were prepared using the KIT-6-templating and polyvinyl alcohol-protected NaBH4 reduction methods,respectively.Various techniques were used to characterize physicochemic...The meso-Co3O4 and AgxAuyPd/meso-Co3O4 catalysts were prepared using the KIT-6-templating and polyvinyl alcohol-protected NaBH4 reduction methods,respectively.Various techniques were used to characterize physicochemical properties of these materials.Catalytic performance of the samples was evaluated for methanol combustion.The cubically crystallized Co3O4 support displayed a three-dimensionally ordered mesoporous structure.The supported noble metal nanoparticles(NPs)possessed a surface area of 115.125 m^2/g,with the noble NPs(average size=2.8.4.5 nm)being uniformly dispersed on the surface of meso-Co3O4.Among all of the samples,0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 showed the highest catalytic activity(T50%=100℃and T90%=112℃at a space velocity of 80000 mL(g^–1 h^–1).The partial deactivation of the 0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 sample due to water vapor or carbon dioxide introduction was reversible.It is concluded that the good catalytic performance of 0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 was associated with its highly dispersed Ag0.75Au1.14Pd alloy NPs,high adsorbed oxygen species concentration,good low-temperature reducibility,and strong interaction between Ag0.75Au1.14Pd alloy NPs and meso-Co3O4.展开更多
A new synthetic strategy has been developed to encapsulate supported Pt nanoparticles in heterogeneous catalysts to prevent their sintering. Model catalysts were first prepared by dispersing -3-nm Pt nanoparticles on ...A new synthetic strategy has been developed to encapsulate supported Pt nanoparticles in heterogeneous catalysts to prevent their sintering. Model catalysts were first prepared by dispersing -3-nm Pt nanoparticles on -120-nm silica beads. These were then covered with a fresh layer of mesoporous silica, a few tens of nanometers thick, and etched to re-expose the metal surface to the reaction mixtures. TEM images were used to confirm the success of each of the synthesis steps, and both CO titrations and kinetic measurements for the catalytic conversion of cis- and trans-2-butenes with hydrogen were employed to test the degree of re-activation of the catalyst obtained after the etching treatment, which had to be tuned to give simultaneous maximum activity and maximum catalyst stability. The resulting encapsulated platinum nanoparticles were shown to resist sintering during calcination at temperatures as high as 1075 K, whereas the unprotected catalysts were seen to sinter by 875 K.展开更多
基金ACKNOWLEDGMENTS This work was supported by the Science Foundation of Chongqing Science and Technology Committee （No.CSTS2009BB4047）, and Innovative Talent Training Project, the Third Stage of ＂211 Project＂ of Chongqing University （No.S-09109）.
文摘TiO2 nanotube arrays （TNTs） electrode loaded with Zn nanoparticles was prepared by anodization and the size of Zn nanoparticle loaded on TNTs electrode was controlled by chronoamperometry deposition time. Results of SEM and XRD analysis show that Zn nanoparticles had a diameter of about 15-25 nm when the deposition time was 3-5 s. The UV-Vis diffuse reflectance spectra show the Zn loaded harvest light with 480-780 nm more effectively than the unloaded sample. The photocurrent response of Zn loaded TNTs electrodes were studied, the results showed that TNTs electrodes loaded with Zn nanoparti-cles has 50% increased photocurrent response under high-pressure mercury lamp irradiation compared with unloaded TNTs electrode.
文摘The effect of a wide variety of metal oxide （MOx） supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under identical calcination conditions, supported gold catalysts were prepared on a wide variety of MOx supports, and the temperature for 50%conversion was measured to qualita‐tively evaluate the catalytic activities of these simple MOx and supported Au catalysts. Furthermore, the difference in these temperatures for the simple MOx compared to the supported Au catalysts is plotted against the metal–oxygen binding energies of the support MOx. A clear volcano‐like correla‐tion between the temperature difference and the metal–oxygen binding energies is observed. This correlation suggests that the use of MOx with appropriate metal–oxygen binding energies （300–500 kJ/atom O） greatly improves the catalytic activity of MOx by the deposition of Au NPs.
基金supported by the National Natural Science Foundation of China(21677004,21876006,and 21622701)the National High Technology Research and Development Program of China(863 Program,2015AA034603)~~
文摘The meso-Co3O4 and AgxAuyPd/meso-Co3O4 catalysts were prepared using the KIT-6-templating and polyvinyl alcohol-protected NaBH4 reduction methods,respectively.Various techniques were used to characterize physicochemical properties of these materials.Catalytic performance of the samples was evaluated for methanol combustion.The cubically crystallized Co3O4 support displayed a three-dimensionally ordered mesoporous structure.The supported noble metal nanoparticles(NPs)possessed a surface area of 115.125 m^2/g,with the noble NPs(average size=2.8.4.5 nm)being uniformly dispersed on the surface of meso-Co3O4.Among all of the samples,0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 showed the highest catalytic activity(T50%=100℃and T90%=112℃at a space velocity of 80000 mL(g^–1 h^–1).The partial deactivation of the 0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 sample due to water vapor or carbon dioxide introduction was reversible.It is concluded that the good catalytic performance of 0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 was associated with its highly dispersed Ag0.75Au1.14Pd alloy NPs,high adsorbed oxygen species concentration,good low-temperature reducibility,and strong interaction between Ag0.75Au1.14Pd alloy NPs and meso-Co3O4.
文摘A new synthetic strategy has been developed to encapsulate supported Pt nanoparticles in heterogeneous catalysts to prevent their sintering. Model catalysts were first prepared by dispersing -3-nm Pt nanoparticles on -120-nm silica beads. These were then covered with a fresh layer of mesoporous silica, a few tens of nanometers thick, and etched to re-expose the metal surface to the reaction mixtures. TEM images were used to confirm the success of each of the synthesis steps, and both CO titrations and kinetic measurements for the catalytic conversion of cis- and trans-2-butenes with hydrogen were employed to test the degree of re-activation of the catalyst obtained after the etching treatment, which had to be tuned to give simultaneous maximum activity and maximum catalyst stability. The resulting encapsulated platinum nanoparticles were shown to resist sintering during calcination at temperatures as high as 1075 K, whereas the unprotected catalysts were seen to sinter by 875 K.
