Catalyst support is extremely important for future fuel cell devices.In this work,we developed doubleshelled C/TiO2(DSCT)hollow spheres as an excellent catalyst support via a template-directed method.The combination o...Catalyst support is extremely important for future fuel cell devices.In this work,we developed doubleshelled C/TiO2(DSCT)hollow spheres as an excellent catalyst support via a template-directed method.The combination of hollow structure,TiO2 shell and carbon layer results in excellent electron conductivity,electrocatalytic activity,and chemical stability.These uniformed DSCT hollow spheres are used as catalyst support to synthesize Pt/DSCT hollow spheres electrocatalyst.The resulting Pt/DSCT hollow spheres exhibited high catalytic performance with a current density of 462 mA mg^-1 for methanol oxidation reaction,which is 2.52 times higher than that of the commercial Pt/C.Furthermore,the increased tolerance to carbonaceous poisoning with a higher If/Ibratio and a better long-term stability in acid media suggests that the DSCT hollow sphere is a promising C/TiO2-based catalyst support for direct methanol fuel cells applications.展开更多
TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was inv...TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was investigated. Compared with Ru/Al_2O_3 catalyst, the Ru/TiO_2–Al_2O_3catalytic system exhibited a much higher activity in CO_2 methanation reaction. The reaction rate over Ru/TiO_2–Al_2O_3 was 0.59 mol CO_2·(g Ru)1·h-1, 3.1 times higher than that on Ru/Al_2O_3[0.19 mol CO_2·(gRu)-1·h-1]. The effect of TiO_2 content and TiO_2–Al_2O_3calcination temperature on catalytic performance was addressed. The corresponding structures of each catalyst were characterized by means of H_2-TPR, XRD, and TEM. Results indicated that the averaged particle size of the Ru on TiO_2–Al_2O_3support is 2.8 nm, smaller than that on Al_2O_3 support of 4.3 nm. Therefore, we conclude that the improved activity over Ru/TiO_2–Al_2O_3catalyst is originated from the smaller particle size of ruthenium resulting from a strong interaction between Ru and the rutile-TiO_2 support, which hindered the aggregation of Ru nanoparticles.展开更多
A new supported amorphous catalyst CoP/TiO2 was prepared by chemical reduction and characterized by ICP, XRD, TEM, BET and DSC. Its application in decomposing PH3 to high purity phosphor and its catalytic activity wer...A new supported amorphous catalyst CoP/TiO2 was prepared by chemical reduction and characterized by ICP, XRD, TEM, BET and DSC. Its application in decomposing PH3 to high purity phosphor and its catalytic activity were studied. The decomposition rate is over 95% at 450 ℃. For comparison, unsupported CoP amorphous catalyst was prepared by the same method. The result suggests that CoP/TiO2 exhibits higher thermal stability and catalytic activity than CoP, which is attributed to the high dispersion of CoP alloy particles on the support-TiO2.展开更多
The supported Au/TiO2 and Au/TiO2-SiO2 catalysts were prepared by deposition precipitation method. The TPD study reveals that propylene oxide competes with propylene to be adsorbed on the same adsorptive center-Ti^n＋...The supported Au/TiO2 and Au/TiO2-SiO2 catalysts were prepared by deposition precipitation method. The TPD study reveals that propylene oxide competes with propylene to be adsorbed on the same adsorptive center-Ti^n＋ site on the surface of the catalyst and that the adisorbing capacity of the catalyst for propylene oxide is larger than that for propylene. Catalytic behavior for propylene epoxidation with H2 and O2 was tested in a micro-reactor. Under typical conditions, the selectivity for propylene oxide is over 87%. The TG curves show that PO successive oxidation cause carbon deposition on the active center and deactivation of the Au catalysts. Because the amounts of Tin＋ site decrease significantly, and consequently the separation between Ti^n＋ sites increases, the Au/TiO2-SiO2 catalyst is more stable than Au/TiO2.展开更多
Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were exa...Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were examined after separate treatment in CO＋O2 or CO2 ＋O2 .Furthermore,in situ FT-IR studies were performed to investigate the species on the surface when CO or CO＋O2 or CO2 ＋O2 was selected separately as adsorption gas.The results showed that Au/Al2O3 catalyst exhibited very high initial activity,but the catalytic activity was found to decrease gradually during CO oxidation with time on stream.And also,the activity of the catalyst declined after treatment in CO＋O2 or CO2 ＋O2 .The formation and accumulation of carbonate-like species during CO oxidation or treatment in CO＋O2 or CO2 ＋O2 might be mainly responsible for the activity decrease,which was reversible.展开更多
The objective of the paper is to report results on fabrication, structural, morphological and performance characteristics of novel TiO2/PS/Si, Au/TiO2/PS/Si and Au/PS/Si direct ammonia fuel cells (DAFC) using nanoporo...The objective of the paper is to report results on fabrication, structural, morphological and performance characteristics of novel TiO2/PS/Si, Au/TiO2/PS/Si and Au/PS/Si direct ammonia fuel cells (DAFC) using nanoporous silicon (PS) as proton conducting membrane (instead of traditional polymer Nafion membrane) and TiO2, Au/TiO2 or Au as catalyst layer. Porous silicon layers have been prepared by electrochemical modification of silicon substrates. Films containing titanium dioxide are more efficient catalysts for hydrogen production from ammonia solution. The Au/ TiO2/PS/Si cell exhibited the open circuit voltage 0.87 V and performance of 1.6 mW/cm2 with 50% ammonia solution as fuel at room temperature. Mechanisms of proton transport in nanoporous silicon membrane and generation of electricity in DAFC have been considered. Advantages of investigated direct ammonia fuel cells consist in simplicity of fabrication technology, which can be integrated into standard silicon micro fabrication processes and operation of cells at room temperature. The work demonstrates that the PS based fuel cells have potential for portable applications.展开更多
PtRu supported on TiO2-embedded carbon nanofibers(PtRu/TECNF),which was recently reported as a highly-active catalyst for methanol oxidation,was applied to a direct methanol fuel cell(DMFC),and the power generation pe...PtRu supported on TiO2-embedded carbon nanofibers(PtRu/TECNF),which was recently reported as a highly-active catalyst for methanol oxidation,was applied to a direct methanol fuel cell(DMFC),and the power generation performance was compared to that using the commercial PtRu/C.Before the comparison,the effect of the catalyst loading on the power density of the DMFC was investigated using PtRu(18 wt%)/TECNF.The DMFC power density showed a maximum at about a 1.5 mg cm2 PtRu loading that corresponds to about an 80 mm layer thickness.A catalyst layer thicker than this value reduced the power density probably due to the concentration overvoltage.The PtRu content in the PtRu/TECNF was then increased to 30 wt%or more to reduce the layer thickness and to increase the power density.The DMFC performance was compared to that of different anode catalysts at a 1 mg cm2 PtRu loading.The power density was maximized using the PtRu30 wt%/TECNF,which showed a 173 mW cm2 at 353 K and had 66 mm layer thick,that was 26%higher than that of commercial PtRu/C.The current–voltage curve of the DMFC with the PtRu/TECNF suggested an improved mass transport overvoltage,but a little improvement in the activation one despite using the catalyst with about a 2 times higher activity compared to that of the commercial PtRu/C.This was attributed to the lower Pt utilization of the nanofiber catalyst layer.展开更多
基金supported by the Scholarship from China Scholarship Council(CSC)(Grant no.201604910621)。
文摘Catalyst support is extremely important for future fuel cell devices.In this work,we developed doubleshelled C/TiO2(DSCT)hollow spheres as an excellent catalyst support via a template-directed method.The combination of hollow structure,TiO2 shell and carbon layer results in excellent electron conductivity,electrocatalytic activity,and chemical stability.These uniformed DSCT hollow spheres are used as catalyst support to synthesize Pt/DSCT hollow spheres electrocatalyst.The resulting Pt/DSCT hollow spheres exhibited high catalytic performance with a current density of 462 mA mg^-1 for methanol oxidation reaction,which is 2.52 times higher than that of the commercial Pt/C.Furthermore,the increased tolerance to carbonaceous poisoning with a higher If/Ibratio and a better long-term stability in acid media suggests that the DSCT hollow sphere is a promising C/TiO2-based catalyst support for direct methanol fuel cells applications.
基金Supported by the National Natural Science Foundation of China(211031735127108721476226 and 51471076)DICP Fundamental Research Program for Clean Energy(DICPM201307)
文摘TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was investigated. Compared with Ru/Al_2O_3 catalyst, the Ru/TiO_2–Al_2O_3catalytic system exhibited a much higher activity in CO_2 methanation reaction. The reaction rate over Ru/TiO_2–Al_2O_3 was 0.59 mol CO_2·(g Ru)1·h-1, 3.1 times higher than that on Ru/Al_2O_3[0.19 mol CO_2·(gRu)-1·h-1]. The effect of TiO_2 content and TiO_2–Al_2O_3calcination temperature on catalytic performance was addressed. The corresponding structures of each catalyst were characterized by means of H_2-TPR, XRD, and TEM. Results indicated that the averaged particle size of the Ru on TiO_2–Al_2O_3support is 2.8 nm, smaller than that on Al_2O_3 support of 4.3 nm. Therefore, we conclude that the improved activity over Ru/TiO_2–Al_2O_3catalyst is originated from the smaller particle size of ruthenium resulting from a strong interaction between Ru and the rutile-TiO_2 support, which hindered the aggregation of Ru nanoparticles.
基金Natural Science Foundation of Tianjin(No.043801311)
文摘A new supported amorphous catalyst CoP/TiO2 was prepared by chemical reduction and characterized by ICP, XRD, TEM, BET and DSC. Its application in decomposing PH3 to high purity phosphor and its catalytic activity were studied. The decomposition rate is over 95% at 450 ℃. For comparison, unsupported CoP amorphous catalyst was prepared by the same method. The result suggests that CoP/TiO2 exhibits higher thermal stability and catalytic activity than CoP, which is attributed to the high dispersion of CoP alloy particles on the support-TiO2.
基金Supported by the National Natural Science Foundation of China (29773031).
文摘The supported Au/TiO2 and Au/TiO2-SiO2 catalysts were prepared by deposition precipitation method. The TPD study reveals that propylene oxide competes with propylene to be adsorbed on the same adsorptive center-Ti^n＋ site on the surface of the catalyst and that the adisorbing capacity of the catalyst for propylene oxide is larger than that for propylene. Catalytic behavior for propylene epoxidation with H2 and O2 was tested in a micro-reactor. Under typical conditions, the selectivity for propylene oxide is over 87%. The TG curves show that PO successive oxidation cause carbon deposition on the active center and deactivation of the Au catalysts. Because the amounts of Tin＋ site decrease significantly, and consequently the separation between Ti^n＋ sites increases, the Au/TiO2-SiO2 catalyst is more stable than Au/TiO2.
基金supported by the Science and Research Reward Fund Program of Shandong Excellent Young Scientist of China (2007BS04033)
文摘Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were examined after separate treatment in CO＋O2 or CO2 ＋O2 .Furthermore,in situ FT-IR studies were performed to investigate the species on the surface when CO or CO＋O2 or CO2 ＋O2 was selected separately as adsorption gas.The results showed that Au/Al2O3 catalyst exhibited very high initial activity,but the catalytic activity was found to decrease gradually during CO oxidation with time on stream.And also,the activity of the catalyst declined after treatment in CO＋O2 or CO2 ＋O2 .The formation and accumulation of carbonate-like species during CO oxidation or treatment in CO＋O2 or CO2 ＋O2 might be mainly responsible for the activity decrease,which was reversible.
文摘The objective of the paper is to report results on fabrication, structural, morphological and performance characteristics of novel TiO2/PS/Si, Au/TiO2/PS/Si and Au/PS/Si direct ammonia fuel cells (DAFC) using nanoporous silicon (PS) as proton conducting membrane (instead of traditional polymer Nafion membrane) and TiO2, Au/TiO2 or Au as catalyst layer. Porous silicon layers have been prepared by electrochemical modification of silicon substrates. Films containing titanium dioxide are more efficient catalysts for hydrogen production from ammonia solution. The Au/ TiO2/PS/Si cell exhibited the open circuit voltage 0.87 V and performance of 1.6 mW/cm2 with 50% ammonia solution as fuel at room temperature. Mechanisms of proton transport in nanoporous silicon membrane and generation of electricity in DAFC have been considered. Advantages of investigated direct ammonia fuel cells consist in simplicity of fabrication technology, which can be integrated into standard silicon micro fabrication processes and operation of cells at room temperature. The work demonstrates that the PS based fuel cells have potential for portable applications.
基金the Element Innovation Project,Ministry of Education,Japan,and by KAKENHI(26289300).
文摘PtRu supported on TiO2-embedded carbon nanofibers(PtRu/TECNF),which was recently reported as a highly-active catalyst for methanol oxidation,was applied to a direct methanol fuel cell(DMFC),and the power generation performance was compared to that using the commercial PtRu/C.Before the comparison,the effect of the catalyst loading on the power density of the DMFC was investigated using PtRu(18 wt%)/TECNF.The DMFC power density showed a maximum at about a 1.5 mg cm2 PtRu loading that corresponds to about an 80 mm layer thickness.A catalyst layer thicker than this value reduced the power density probably due to the concentration overvoltage.The PtRu content in the PtRu/TECNF was then increased to 30 wt%or more to reduce the layer thickness and to increase the power density.The DMFC performance was compared to that of different anode catalysts at a 1 mg cm2 PtRu loading.The power density was maximized using the PtRu30 wt%/TECNF,which showed a 173 mW cm2 at 353 K and had 66 mm layer thick,that was 26%higher than that of commercial PtRu/C.The current–voltage curve of the DMFC with the PtRu/TECNF suggested an improved mass transport overvoltage,but a little improvement in the activation one despite using the catalyst with about a 2 times higher activity compared to that of the commercial PtRu/C.This was attributed to the lower Pt utilization of the nanofiber catalyst layer.
