Using Cu-BTC prepared by hydrothermal method as precursor, carbon-based catalysts were obtained as model materials for low-temperature DeNO_x. These catalysts were characterized by X-ray diffractometry（XRD）, Raman s...Using Cu-BTC prepared by hydrothermal method as precursor, carbon-based catalysts were obtained as model materials for low-temperature DeNO_x. These catalysts were characterized by X-ray diffractometry（XRD）, Raman spectroscopy, scanning electron microscopy（SEM） and energy dispersive X-ray spectrometry（EDS）. The results showed that all carbon-based catalysts held the octahedron shape of Cu-BTC in most parts, and they mainly consisted of face-centered cubic copper. CuO_x/C exhibited excellent catalytic activity, and such catalytic activity was further improved with the introduction of Ag. The catalyst with a Cu to Ag mole ratio of 6：1 and an activated temperature of 600 °C showed the best catalytic performance, and its catalytic denitration rate reached 100% at a temperature as low as 235 °C. During the catalytic reaction process, Cu~＋ mainly played a catalytic role.展开更多
Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells.Fe-N compounds with excellent electrocatalytic oxygen...Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells.Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells,which focuses on the Fe-N4 single-atom catalysts and the iron nitride materials(such as Fe2N and Fe3N).A hybridized catalyst having a hierarchical porous structure with regular macropores could enable the desired mass transfer efficiency in the catalytic process.In this study,we have constructed a new type of hybrid catalyst having iron and iron-nitrogen alloy nanoparticles(Fe-N austenite,termed as Fe-NA)embedded in the three-dimensional ordered macroporous N-doped carbon(3DOM Fe/Fe-NA@NC)by direct pyrolysis of single-source dicyandiamide-based iron metal-organic frameworks.The as-synthesized composites preserve the hierarchical porous carbon framework with ordered macropores and high specific surface area,incorporating the uniformly dispersed iron/iron-nitrogen austenite nanoparticles.Thereby,the striking architectural configuration embedded with highly active catalytic species delivers a superior oxygen reduction activity with a half-wave potential of 0.88 V and a subsequent superior Zn-air battery performance with high open-circuit voltage and continuous stability as compared to those using a commercial 20%Pt/C catalyst.展开更多
This vertically self‐pillared(VSP)structure extends the application range of traditional porous materials with facile mass/ion transport and enhanced reaction kinetics.Here,we prepare a single crystal metal‐organic ...This vertically self‐pillared(VSP)structure extends the application range of traditional porous materials with facile mass/ion transport and enhanced reaction kinetics.Here,we prepare a single crystal metal‐organic framework(MOF),employing the ZIF‐67 structure as a proof of concept,which is constructed by vertically self‐pillared nanosheets(VSP‐MOF).We further converted VSP‐MOF into VSP‐cobalt sulfide(VSP‐CoS2)through a sulfidation process.Catalysis plays an important role in almost all battery technologies;for metallic batteries,lithium anodes exhibit a high theoretical specific capacity,low density,and low redox potential.However,during the half‐cell reaction(Li++e=Li),uncontrolled dendritic Li penetrates the separator and solid electrolyte interphase layer.When employed as a composite scaffold for lithium metal deposition,there are many advantage to using this framework:1)the VSP‐CoS2 substrate provides a high specific surface area to dissipate the ion flux and mass transfer and acts as a pre‐catalyst,2)the catalytic Co center favors the charge transfer process and preferentially binds the Li+with the enhanced electrical fields,and 3)the VSP structure guides the metallic propagation along the nanosheet 2D orientation without the protrusive dendrites.All these features enable the VSP structure in metallic batteries with encouraging performances.展开更多
In this paper, we reported a solvothermal method for the synthesis of octahedral Pt-Cu bimetallic alloy nanocrystals （NCs） with tunable composition. Inspired by the result from our previous exploration on octahedral...In this paper, we reported a solvothermal method for the synthesis of octahedral Pt-Cu bimetallic alloy nanocrystals （NCs） with tunable composition. Inspired by the result from our previous exploration on octahedral Pt-Cu alloy NCs that Cu contents can be tuned from 10 % to 50 %, we further tuned the Cu portion from 50 % to 75 % by simply introducing n-butylamine in the reaction system. It is believed that n-butylamine plays a key role in breaking through a thermodynamic constraint in the formation of Pt-Cu alloy nanocrystals （NCs）. The synergistic effect of underpotential deposition-like Cu reduction and the different complexion abilities of amine group of n-butylamine with two metal species effectively tuned the reduction kinetics, by which each reduced Pt atom is able to catalyze reduction of more Cu atoms and be fully covered with 12 Cu atoms in the Pt-Cu alloy crystal, while Cu precursor is not able to be reduced solely and bind solely with Cu atoms, resulting in the successful tuning of Cu composition from 50 % to 75 %. In addition, we investigated the electro-catalytic activity of Pt-Cu bimetallic alloy NCs with different composition in electro-oxidation of methanol. The as-prepared PtCu3 NCs exhibit excellent electro-catalytic performance and stability in comparison with commercial Pt black and other compositional Pt-Cu alloy NCs.展开更多
基金Project(738010004)supported by the Project of Low Concentration Sulfur Dioxide Flue Gas Treatment,ChinaProject(2017GK4010)supported by the Scientific and Technological Breakthrough and Major Achievements Transformation of Strategic Emerging Industries of Hunan Province in 2017,China
文摘Using Cu-BTC prepared by hydrothermal method as precursor, carbon-based catalysts were obtained as model materials for low-temperature DeNO_x. These catalysts were characterized by X-ray diffractometry（XRD）, Raman spectroscopy, scanning electron microscopy（SEM） and energy dispersive X-ray spectrometry（EDS）. The results showed that all carbon-based catalysts held the octahedron shape of Cu-BTC in most parts, and they mainly consisted of face-centered cubic copper. CuO_x/C exhibited excellent catalytic activity, and such catalytic activity was further improved with the introduction of Ag. The catalyst with a Cu to Ag mole ratio of 6：1 and an activated temperature of 600 °C showed the best catalytic performance, and its catalytic denitration rate reached 100% at a temperature as low as 235 °C. During the catalytic reaction process, Cu~＋ mainly played a catalytic role.
文摘Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells.Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells,which focuses on the Fe-N4 single-atom catalysts and the iron nitride materials(such as Fe2N and Fe3N).A hybridized catalyst having a hierarchical porous structure with regular macropores could enable the desired mass transfer efficiency in the catalytic process.In this study,we have constructed a new type of hybrid catalyst having iron and iron-nitrogen alloy nanoparticles(Fe-N austenite,termed as Fe-NA)embedded in the three-dimensional ordered macroporous N-doped carbon(3DOM Fe/Fe-NA@NC)by direct pyrolysis of single-source dicyandiamide-based iron metal-organic frameworks.The as-synthesized composites preserve the hierarchical porous carbon framework with ordered macropores and high specific surface area,incorporating the uniformly dispersed iron/iron-nitrogen austenite nanoparticles.Thereby,the striking architectural configuration embedded with highly active catalytic species delivers a superior oxygen reduction activity with a half-wave potential of 0.88 V and a subsequent superior Zn-air battery performance with high open-circuit voltage and continuous stability as compared to those using a commercial 20%Pt/C catalyst.
文摘This vertically self‐pillared(VSP)structure extends the application range of traditional porous materials with facile mass/ion transport and enhanced reaction kinetics.Here,we prepare a single crystal metal‐organic framework(MOF),employing the ZIF‐67 structure as a proof of concept,which is constructed by vertically self‐pillared nanosheets(VSP‐MOF).We further converted VSP‐MOF into VSP‐cobalt sulfide(VSP‐CoS2)through a sulfidation process.Catalysis plays an important role in almost all battery technologies;for metallic batteries,lithium anodes exhibit a high theoretical specific capacity,low density,and low redox potential.However,during the half‐cell reaction(Li++e=Li),uncontrolled dendritic Li penetrates the separator and solid electrolyte interphase layer.When employed as a composite scaffold for lithium metal deposition,there are many advantage to using this framework:1)the VSP‐CoS2 substrate provides a high specific surface area to dissipate the ion flux and mass transfer and acts as a pre‐catalyst,2)the catalytic Co center favors the charge transfer process and preferentially binds the Li+with the enhanced electrical fields,and 3)the VSP structure guides the metallic propagation along the nanosheet 2D orientation without the protrusive dendrites.All these features enable the VSP structure in metallic batteries with encouraging performances.
基金supported by the National Basic Research Program of China(2011CBA00508 and 2015CB932301)the National Natural Science Foundation of China(21131005,21333008,and J1310024)the Natural Science Foundation of Fujian Province of China(2014J01058)
文摘In this paper, we reported a solvothermal method for the synthesis of octahedral Pt-Cu bimetallic alloy nanocrystals （NCs） with tunable composition. Inspired by the result from our previous exploration on octahedral Pt-Cu alloy NCs that Cu contents can be tuned from 10 % to 50 %, we further tuned the Cu portion from 50 % to 75 % by simply introducing n-butylamine in the reaction system. It is believed that n-butylamine plays a key role in breaking through a thermodynamic constraint in the formation of Pt-Cu alloy nanocrystals （NCs）. The synergistic effect of underpotential deposition-like Cu reduction and the different complexion abilities of amine group of n-butylamine with two metal species effectively tuned the reduction kinetics, by which each reduced Pt atom is able to catalyze reduction of more Cu atoms and be fully covered with 12 Cu atoms in the Pt-Cu alloy crystal, while Cu precursor is not able to be reduced solely and bind solely with Cu atoms, resulting in the successful tuning of Cu composition from 50 % to 75 %. In addition, we investigated the electro-catalytic activity of Pt-Cu bimetallic alloy NCs with different composition in electro-oxidation of methanol. The as-prepared PtCu3 NCs exhibit excellent electro-catalytic performance and stability in comparison with commercial Pt black and other compositional Pt-Cu alloy NCs.
