Highly dispersed,high performance Pt and PtRu catalysts,supported on multiwalled carbon nanotubes(CNTs),were prepared by a high pressure organic colloid method.The particle sizes of the active components were as small...Highly dispersed,high performance Pt and PtRu catalysts,supported on multiwalled carbon nanotubes(CNTs),were prepared by a high pressure organic colloid method.The particle sizes of the active components were as small as 1.2 nm for Pt and 1.1 nm for PtRu,and the active Pt surface areas were 295 and 395 m2/g,respectively.The catalysts showed very high activities toward the anodic oxidation of methanol,evaluated by cyclic voltammetry,being up to 4 times higher than that of commercial Johnson Matthey Hispec 2000 Pt/XC-72R and 5 times better than Hispec 5000 PtRu/XC-72R catalysts.In a full air/hydrogen fuel cell,a membrane-electrode assembly prepared using our Pt/CNT and PtRu/CNT catalysts showed 50% and 100% higher performances than those prepared with commercial Johnson Matthey Pt/XC-72R and PtRu/XC-72R catalysts for the same Pt loading and operating conditions.展开更多
Traditional modifications to hydroxyapatite （HA） nanoparticles usually occurred after HA synthesis and thus are insufficient to avoid particle agglomeration. In this study, a new heterofunctional poly（ethylene gly...Traditional modifications to hydroxyapatite （HA） nanoparticles usually occurred after HA synthesis and thus are insufficient to avoid particle agglomeration. In this study, a new heterofunctional poly（ethylene glycol） （PEG） with phosphoric acid and carboxyl end groups, Le., a-（N-2-phosphoethyl phosphoric acid）- amide, w-carboxyl-bismethyoxy poly（ethylene glycol） （ADP-PEG-COOH）, was synthesized as an in situ surface modifier to HA nanoparticles. The resulting modified HA （ADP-PEG-HA） can disperse in methanol, forming a colloid stabilized by peripheral carboxyl-endcapped PEG chains. The colloidal particles resembled nanospheres which agglomerated to some extent under examination by transmission electron microscope. This highly dispersible HA nanoparticles in organic solvent might find application in preparing new HA nanocomposites.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 20676032,20876062)
文摘Highly dispersed,high performance Pt and PtRu catalysts,supported on multiwalled carbon nanotubes(CNTs),were prepared by a high pressure organic colloid method.The particle sizes of the active components were as small as 1.2 nm for Pt and 1.1 nm for PtRu,and the active Pt surface areas were 295 and 395 m2/g,respectively.The catalysts showed very high activities toward the anodic oxidation of methanol,evaluated by cyclic voltammetry,being up to 4 times higher than that of commercial Johnson Matthey Hispec 2000 Pt/XC-72R and 5 times better than Hispec 5000 PtRu/XC-72R catalysts.In a full air/hydrogen fuel cell,a membrane-electrode assembly prepared using our Pt/CNT and PtRu/CNT catalysts showed 50% and 100% higher performances than those prepared with commercial Johnson Matthey Pt/XC-72R and PtRu/XC-72R catalysts for the same Pt loading and operating conditions.
基金sponsored by the National Natural Science Foundation of China(No.50973069)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(No.20101561-3-3)
文摘Traditional modifications to hydroxyapatite （HA） nanoparticles usually occurred after HA synthesis and thus are insufficient to avoid particle agglomeration. In this study, a new heterofunctional poly（ethylene glycol） （PEG） with phosphoric acid and carboxyl end groups, Le., a-（N-2-phosphoethyl phosphoric acid）- amide, w-carboxyl-bismethyoxy poly（ethylene glycol） （ADP-PEG-COOH）, was synthesized as an in situ surface modifier to HA nanoparticles. The resulting modified HA （ADP-PEG-HA） can disperse in methanol, forming a colloid stabilized by peripheral carboxyl-endcapped PEG chains. The colloidal particles resembled nanospheres which agglomerated to some extent under examination by transmission electron microscope. This highly dispersible HA nanoparticles in organic solvent might find application in preparing new HA nanocomposites.
