Designing Fischer-Tropsch synthesis(FTS)catalysts to selectively produce liquid hydrocarbon fuels is a crucial challenge.Herein,we selectively introduced Co nanoparticles(NPs)into the micropores and mesopores of an or...Designing Fischer-Tropsch synthesis(FTS)catalysts to selectively produce liquid hydrocarbon fuels is a crucial challenge.Herein,we selectively introduced Co nanoparticles(NPs)into the micropores and mesopores of an ordered mesoporous MFI zeolite(OMMZ)through impregnation,which controlled the carbon number distribution in the FTS products by tuning the position of catalytic active sites in differently sized pores.The Co precursors coordinated by acetate with a size of 9.4×4.2×2.5Åand by 2,2'-bipyridine with a size of 9.5×8.7×7.9Å,smaller and larger than the micropores(ca.5.5Å)of MFI,made the Co species incorporated in OMMZ's micropores and mesopores,respectively.The carbon number products synthesized with the Co NPs confined in mesopores were larger than that in micropores.The high jet and diesel selectivities of 66.5%and 65.3%were achieved with Co NPs confined in micropores and mesopores of less acidic Na-type OMMZ,respectively.Gasoline and jet selectivities of 76.7%and 70.8%were achieved with Co NPs confined in micropores and mesopores of H-type OMMZ with Brönsted acid sites,respectively.A series of characterizations revealed that the selective production of diesel and jet fuels was due to the C-C cleavage suppressing of heavier hydrocarbons by the Co NPs located in mesopores.展开更多
The monodispersed Co nanoparticles were successfully prepared by means of hydrogen plasma method in inert atmosphere. The particle size, specific surface area, crystal structure and morphology of the samples were char...The monodispersed Co nanoparticles were successfully prepared by means of hydrogen plasma method in inert atmosphere. The particle size, specific surface area, crystal structure and morphology of the samples were characterized by transmission electron microscopy （TEM）, BET equation, X-ray diffraction （XRD）, and the corresponding selected area electron diffraction （SAED）. The catalytic effect of Co nanoparticles on the decomposition of ammonium perchlorate （AP） was investigated by differential thermal analyzer （DTA）. Compared with the thermal decomposition of pure AP, the addition of Co nanoparticles （2%-10%, by mass） decreases the decomposition temperature of AP by 145.01-155.72℃. Compared with Co3O4 nano-particles and microsized Co particles, the catalytic effect of Co nanoparticles for AP is stronger. Such effect is attributed to the large specific surface area and its interaction of Co with decomposition intermediate gases. The present work provides useful information for the application of Co nanoparficles in the AP-based propellant.展开更多
The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐co...The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐containing intermediates during the 4e–ORR offers a practical route toward improving ORR kinetics.Herein,we designed a novel ORR electrocatalyst containing Co single atoms and nanoparticles supported by carbon dots‐derived carbon nanoflowers(Co SAs/NPs CNF).Co SAs/NPs CNF possessed a very high ORR activity(E_(1/2) of the Co SAs/NPs CNF catalyst is 0.83 V(vs.RHE)),and outstanding catalytic performance and stability when used as the air‐electrode catalyst in rechargeable ZABs(152.32 mW cm^(-2),1000.58 mWh gZn^(–1),and over 1300 cycles at a current density of 5 mA cm^(-2)).The Co SAs and Co NPs cooperated to improve electron and proton transfer processes during ORR.Theoretical calculations revealed that the presence of adjacent Co NPs optimized the electronic structure of the isolated Co‐N_(4) sites,significantly lowering the energy barriers for the rate‐determining step in ORR(adsorption of*OOH)and thereby delivering outstanding ORR performance.This work reveals that the combination of supported single‐atom sites and metal nanoparticles can be highly beneficial for ORR electrocatalysis,outperforming catalysts containing only Co SAs or Co NPs.展开更多
Electromagnetic pollution and heat dissipation problems are becoming increasingly worthy of attention due to the rapid development of electronic devices,which puts forward an urgent demand for microwave absorbers with...Electromagnetic pollution and heat dissipation problems are becoming increasingly worthy of attention due to the rapid development of electronic devices,which puts forward an urgent demand for microwave absorbers with excellent thermal management performance.Herein,high-performance Co/carbon nanofiber(Co/CNF)microwave absorbers with high thermal conductivity were fabricated by facile step-by-step method.The microwave absorption properties can be readily tuned by adjusting the content and size of Co nanoparticles through concentration gradient adsorption.Benefiting from the formation of dielectric and magnetic coupling network,Co/CNF composites possess intensive dipole polarization,interface polarization,and magnetic loss.The optimal Co/CNF composites exhibit outstanding microwave absorption performance with a minimum reflection loss(RL)of−53.0 dB at 11.44 GHz,and a maximum effective absorption bandwidth(EAB)of 5.5 GHz.In addition,the thermal conductivities of the Co/CNF-natural rubber(Co/CNF-NR)composites are significantly improved.This work may inspire the exploration of high-efficiency heat-conduction microwave absorbers based on CNF.展开更多
Based on the volcanic relationship between catalytic activity and key adsorption energies,Pt-Co alloy materials have been widely studied as cathode oxygen reduction reaction(ORR)catalysts in proton exchange membrane f...Based on the volcanic relationship between catalytic activity and key adsorption energies,Pt-Co alloy materials have been widely studied as cathode oxygen reduction reaction(ORR)catalysts in proton exchange membrane fuel cells(PEMFCs)due to their higher active surface area and adjustable D-band energy levels compared to Pt/C.However,how to balance the alloying degree and ORR performance of Pt-Co catalyst remains a great challenge.Herein,we first synthesized a well-dispersed Pt/Co/C precursor by using a mild dimethylamine borane(DMAB)as the reducing agent.The precursor was calcined at high temperature under H_(2)/Ar mixed gas by a secondary reduction strategy to obtain an ordered Pt_(3)Co intermetallic compound nanoparticle catalyst with a high degree of alloying.The optimization of elec-tronic structure due to Pt-Co alloying and the strong metal-carrier interaction ensure the high kinetic activity of the cell membrane electrode.Additionally,the high degree of graphitization increases the electrical conductivity during the reaction.As a result,the activity and stability of the catalyst were significantly improved,with a half-wave potential as high as 0.87 V,which decreased by only 20 mV after 10000 potential cycles.Single-cell tests further validate the high intrinsic activity of the ordered Pt_(3)Co catalyst with mass activity up to 0.67 A mg_(pt)^(-1),exceeding the United States Department of Energy(US DOE)standard(0.44 A mg_(pt)^(-1)),and a rated power of 5.93 W mg_(pt)^(-1).展开更多
Over the past decade,metal nanoparticles(MNPs)have attracted extensive attention due to their unique physiochemical properties that make them highly applicable in various fields such as chemical sensing,energy storage...Over the past decade,metal nanoparticles(MNPs)have attracted extensive attention due to their unique physiochemical properties that make them highly applicable in various fields such as chemical sensing,energy storage,catalysis,medicine,and environmental engineering.Their physiochemical properties depend drastically on the MNP size and morphology,which are largely determined by their synthesis methods.Research on MNPs predominantly focused on coinage metals(Au,Ag and Cu),but in the last decade research on metals with a relatively high melting temperature such as Pd,Co,and Re has seen rapid increases,mainly driven by their potential applications as catalysts.This paper presents the recent advances on different synthesis techniques of Co,Pd,and Re nanoparticles,their resulting nanostructures,as well as existing and potential applications.展开更多
Both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are crucial for advancing the industrial application of fuel cells and metal-air batteries.This paper reports a bifunctional oxygen catalyst(CoNC@Fe...Both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are crucial for advancing the industrial application of fuel cells and metal-air batteries.This paper reports a bifunctional oxygen catalyst(CoNC@FePc)synthesized by anchoring FePc molecules onto cobalt nanoparticles embedded within a Co-ZIF-derived nitrogen-doped carbon matrix(CoNC).By leveraging the significant electron transfer between Co nanoparticles and FePc molecules,the synthesized catalyst demonstrated outstanding performance for both ORR and OER,further validated by density functional theory(DFT)calculations.The catalyst achieved a half-wave potential of 0.87 V for ORR and a low overpotential of 314 mV at 10 mA/cm^(2)for OER,surpassing the performance of commercial Pt/C and RuO_(2),respectively.Additionally,the rechargeable zinc-air batteries incorporating CoNC@FePc exhibited a remarkable peak power density of 150.2 mW/cm^(2)and maintained outstanding cyclic stability for over 100 h.This study offers a straightforward approach to improving the bifunctional oxygen electrocatalytic performance of metal phthalocyaninebased catalysts.展开更多
文摘Designing Fischer-Tropsch synthesis(FTS)catalysts to selectively produce liquid hydrocarbon fuels is a crucial challenge.Herein,we selectively introduced Co nanoparticles(NPs)into the micropores and mesopores of an ordered mesoporous MFI zeolite(OMMZ)through impregnation,which controlled the carbon number distribution in the FTS products by tuning the position of catalytic active sites in differently sized pores.The Co precursors coordinated by acetate with a size of 9.4×4.2×2.5Åand by 2,2'-bipyridine with a size of 9.5×8.7×7.9Å,smaller and larger than the micropores(ca.5.5Å)of MFI,made the Co species incorporated in OMMZ's micropores and mesopores,respectively.The carbon number products synthesized with the Co NPs confined in mesopores were larger than that in micropores.The high jet and diesel selectivities of 66.5%and 65.3%were achieved with Co NPs confined in micropores and mesopores of less acidic Na-type OMMZ,respectively.Gasoline and jet selectivities of 76.7%and 70.8%were achieved with Co NPs confined in micropores and mesopores of H-type OMMZ with Brönsted acid sites,respectively.A series of characterizations revealed that the selective production of diesel and jet fuels was due to the C-C cleavage suppressing of heavier hydrocarbons by the Co NPs located in mesopores.
基金Supported by the National Natural Science Foundation of China （50306008, 50602024）.
文摘The monodispersed Co nanoparticles were successfully prepared by means of hydrogen plasma method in inert atmosphere. The particle size, specific surface area, crystal structure and morphology of the samples were characterized by transmission electron microscopy （TEM）, BET equation, X-ray diffraction （XRD）, and the corresponding selected area electron diffraction （SAED）. The catalytic effect of Co nanoparticles on the decomposition of ammonium perchlorate （AP） was investigated by differential thermal analyzer （DTA）. Compared with the thermal decomposition of pure AP, the addition of Co nanoparticles （2%-10%, by mass） decreases the decomposition temperature of AP by 145.01-155.72℃. Compared with Co3O4 nano-particles and microsized Co particles, the catalytic effect of Co nanoparticles for AP is stronger. Such effect is attributed to the large specific surface area and its interaction of Co with decomposition intermediate gases. The present work provides useful information for the application of Co nanoparficles in the AP-based propellant.
文摘The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐containing intermediates during the 4e–ORR offers a practical route toward improving ORR kinetics.Herein,we designed a novel ORR electrocatalyst containing Co single atoms and nanoparticles supported by carbon dots‐derived carbon nanoflowers(Co SAs/NPs CNF).Co SAs/NPs CNF possessed a very high ORR activity(E_(1/2) of the Co SAs/NPs CNF catalyst is 0.83 V(vs.RHE)),and outstanding catalytic performance and stability when used as the air‐electrode catalyst in rechargeable ZABs(152.32 mW cm^(-2),1000.58 mWh gZn^(–1),and over 1300 cycles at a current density of 5 mA cm^(-2)).The Co SAs and Co NPs cooperated to improve electron and proton transfer processes during ORR.Theoretical calculations revealed that the presence of adjacent Co NPs optimized the electronic structure of the isolated Co‐N_(4) sites,significantly lowering the energy barriers for the rate‐determining step in ORR(adsorption of*OOH)and thereby delivering outstanding ORR performance.This work reveals that the combination of supported single‐atom sites and metal nanoparticles can be highly beneficial for ORR electrocatalysis,outperforming catalysts containing only Co SAs or Co NPs.
基金supported by the National Natural Science Foundation of China(Grant Nos.22068010,22168016,51875318,52175341)the Natural Science Foundation of Hainan Province(Grant Nos.2019RC142,120RC454,519QN176)the Finance Science and technology project of Hainan Province(Grant No.ZDYF2020009).
文摘Electromagnetic pollution and heat dissipation problems are becoming increasingly worthy of attention due to the rapid development of electronic devices,which puts forward an urgent demand for microwave absorbers with excellent thermal management performance.Herein,high-performance Co/carbon nanofiber(Co/CNF)microwave absorbers with high thermal conductivity were fabricated by facile step-by-step method.The microwave absorption properties can be readily tuned by adjusting the content and size of Co nanoparticles through concentration gradient adsorption.Benefiting from the formation of dielectric and magnetic coupling network,Co/CNF composites possess intensive dipole polarization,interface polarization,and magnetic loss.The optimal Co/CNF composites exhibit outstanding microwave absorption performance with a minimum reflection loss(RL)of−53.0 dB at 11.44 GHz,and a maximum effective absorption bandwidth(EAB)of 5.5 GHz.In addition,the thermal conductivities of the Co/CNF-natural rubber(Co/CNF-NR)composites are significantly improved.This work may inspire the exploration of high-efficiency heat-conduction microwave absorbers based on CNF.
基金supported by the National Key Research and Development Program of China(grant No.2022YFB3807500)the National Natural Science Foundation of China(grant No.21922802,22220102003)+1 种基金the Beijing Natural Science Foundation(grant No.JQ19007)“Double-First-Class”construction projects(grant No.XK180301,XK1804-02).
文摘Based on the volcanic relationship between catalytic activity and key adsorption energies,Pt-Co alloy materials have been widely studied as cathode oxygen reduction reaction(ORR)catalysts in proton exchange membrane fuel cells(PEMFCs)due to their higher active surface area and adjustable D-band energy levels compared to Pt/C.However,how to balance the alloying degree and ORR performance of Pt-Co catalyst remains a great challenge.Herein,we first synthesized a well-dispersed Pt/Co/C precursor by using a mild dimethylamine borane(DMAB)as the reducing agent.The precursor was calcined at high temperature under H_(2)/Ar mixed gas by a secondary reduction strategy to obtain an ordered Pt_(3)Co intermetallic compound nanoparticle catalyst with a high degree of alloying.The optimization of elec-tronic structure due to Pt-Co alloying and the strong metal-carrier interaction ensure the high kinetic activity of the cell membrane electrode.Additionally,the high degree of graphitization increases the electrical conductivity during the reaction.As a result,the activity and stability of the catalyst were significantly improved,with a half-wave potential as high as 0.87 V,which decreased by only 20 mV after 10000 potential cycles.Single-cell tests further validate the high intrinsic activity of the ordered Pt_(3)Co catalyst with mass activity up to 0.67 A mg_(pt)^(-1),exceeding the United States Department of Energy(US DOE)standard(0.44 A mg_(pt)^(-1)),and a rated power of 5.93 W mg_(pt)^(-1).
基金This work was financially supported by National Institutes of Health(NIH)(Grant No.R15CA199019)Cancer Prevention Research Institute of Texas(CPRIT)(Grant No.PR190678).
文摘Over the past decade,metal nanoparticles(MNPs)have attracted extensive attention due to their unique physiochemical properties that make them highly applicable in various fields such as chemical sensing,energy storage,catalysis,medicine,and environmental engineering.Their physiochemical properties depend drastically on the MNP size and morphology,which are largely determined by their synthesis methods.Research on MNPs predominantly focused on coinage metals(Au,Ag and Cu),but in the last decade research on metals with a relatively high melting temperature such as Pd,Co,and Re has seen rapid increases,mainly driven by their potential applications as catalysts.This paper presents the recent advances on different synthesis techniques of Co,Pd,and Re nanoparticles,their resulting nanostructures,as well as existing and potential applications.
基金supported by the Basic Science and Technology Research Project of Wenzhou,Zhejiang Province,China(No.G20240038)the Special Basic Cooperative Research Programs of Yunnan Provincial Undergraduate Universities Association,China(Nos.202301BA070001-093 and 202401BA070001-002).
文摘Both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are crucial for advancing the industrial application of fuel cells and metal-air batteries.This paper reports a bifunctional oxygen catalyst(CoNC@FePc)synthesized by anchoring FePc molecules onto cobalt nanoparticles embedded within a Co-ZIF-derived nitrogen-doped carbon matrix(CoNC).By leveraging the significant electron transfer between Co nanoparticles and FePc molecules,the synthesized catalyst demonstrated outstanding performance for both ORR and OER,further validated by density functional theory(DFT)calculations.The catalyst achieved a half-wave potential of 0.87 V for ORR and a low overpotential of 314 mV at 10 mA/cm^(2)for OER,surpassing the performance of commercial Pt/C and RuO_(2),respectively.Additionally,the rechargeable zinc-air batteries incorporating CoNC@FePc exhibited a remarkable peak power density of 150.2 mW/cm^(2)and maintained outstanding cyclic stability for over 100 h.This study offers a straightforward approach to improving the bifunctional oxygen electrocatalytic performance of metal phthalocyaninebased catalysts.
