The design and development of low-cost,efficient,and stable bifunctional electrocatalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desirable for rechargeable metal-air batteries.In t...The design and development of low-cost,efficient,and stable bifunctional electrocatalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desirable for rechargeable metal-air batteries.In this work,N-doped porous hollow carbon spheres encapsulated with ultrafine Fe/Fe3O4 nanoparticles(FeOx@N-PHCS)were fabricated by impregnation and subsequent pyrolysis,using melamine-formaldehyde resin spheres as self-sacrifice templates and polydopamine as N and C sources.The sufficient adsorption of Fe3+on the polydopamine endowed the formation of Fe-Nx species upon high-temperature carbonization.The prepared FeOx@N-PHCS has advanced features of large specific surface area,porous hollow structure,high content of N dopants,sufficient Fe-Nx species and ultrafine FeOx nanoparticles.These features endow FeOx@N-PHCS with enhanced mass transfer and considerable active sites,leading to high activity and stability in catalyzing ORR and OER in alkaline electrolyte.Furthermore,the rechargeable Zn-air battery with FeOx@N-PHCS as air cathode catalyst exhibits a large peak power density,narrow charge-discharge potential gap and robust cycling stability,demonstrating the potential of the fabricated FeOx@N-PHCS as a promising electrode material for metal-air batteries.This new finding may open an avenue for rational design of bifunctional catalysts by integrating different active components within all-in-one catalyst for different electrochemical reactions.展开更多
Interfacial atomic configuration between dual-metal active species and nitrogen-carbon substrates is of great importance for improving the intrinsic activity of catalysts toward oxygen reduction reaction(ORR).Thus,fro...Interfacial atomic configuration between dual-metal active species and nitrogen-carbon substrates is of great importance for improving the intrinsic activity of catalysts toward oxygen reduction reaction(ORR).Thus,from the atomic-scale engineering we develop a high intrinsic activity ORR catalyst in terms of incorporating atomically dispersed dual Fe centers(single Fe atoms and ultra-small Fe atomic clusters)into bamboo-like N-doped carbon nanotubes.Benefiting from atomically dispersed dual-Fe centers on the atomic interface of Fe-Nx/carbon nanotubes,the fabricated dual Fe centers catalyst exhibits an extremely high ORR activity(E_(onset)=1.006 V;E_(1/2)=0.90 V),beyond state-of-the-art Pt/C.Remarkably,this catalyst also shows a superior kinetic current density of 19.690 mA·cm^(−2),which is 7 times that of state-of-the-art Pt/C.Additionally,based on the excellent catalyst,the primary Zn-air battery reveals a high power density up to 137 mW·cm^(−2) and sufficient potential cycling stability(at least 25 h).Undoubtedly,given the unique structure–activity relationship of dual-Fe active species and metal-nitrogen-carbon substrates,the catalyst will show great prospects in highly efficient electrochemical energy conversion devices.展开更多
The electrochemical conversion of CO_(2)-H_(2)O into CO-H_(2) using renewable energy is a promising technique for clean syngas production.Low-cost electrocatalysts to produce tunable syngas with a potential-independen...The electrochemical conversion of CO_(2)-H_(2)O into CO-H_(2) using renewable energy is a promising technique for clean syngas production.Low-cost electrocatalysts to produce tunable syngas with a potential-independent CO/H_(2) ratio are highly desired.Herein,a series of N-doped carbon nanotubes encapsulating binary alloy nanoparticles(MxNi-NCNT,M=Fe,Co)were successfully fabricated through the co-pyrolysis of melamine and metal precursors.The MxNi-NCNT samples exhibited bamboo-like nanotubular structures with a large specific surface area and high degree of graphitization.Their electrocatalytic performance for syngas production can be tuned by changing the alloy compositions and modifying the electronic structure of the carbon nanotube through the encapsulated metal nanoparticles.Consequently,syngas with a wide range of CO/H_(2) ratios,from 0.5:1 to 3.4:1,can be produced on MxNi-NCNT.More importantly,stable CO/H_(2) ratios of 2:1 and 1.5:1,corresponding to the ratio to produce biofuels by syngas fermentation,could be realized on Co1Ni-NCNT and Co2Ni-NCNT,respectively,over a potential window of-0.8 to-1.2 V versus the reversible hydrogen electrode.Our work provides an approach to develop low-cost and potential-independent electrocatalysts to effectively produce syngas with an adjustable CO/H_(2) ratio from electrochemical CO_(2) reduction.展开更多
Three dimensional（3D） nano-LiMn0.6Fe0.4PO4@C/CNT composite was successfully synthesized by an oleylamine-assisted solvothermal method. The prepared composite showed excellent electrochemical performance, especially ...Three dimensional（3D） nano-LiMn0.6Fe0.4PO4@C/CNT composite was successfully synthesized by an oleylamine-assisted solvothermal method. The prepared composite showed excellent electrochemical performance, especially superior high rate capability. It could deliver a specific discharge capacity of103.1 mAh/g, even at 80 C. The superior high rate performance of the as-prepared LiMn0.6Fe0.4PO4@C/CNT electrode is attributed to its unique 3D conducting network：（1） the prepared LiMn0.6Fe0.4PO4@C active particles were in nano-scale with a size of 30-50 nm;（2） LiMn0.6Fe0.4PO4 nanoparticles were uniformly coated by amorphous carbon with a thickness of 3 nm;（3） the graphitized conductive CNTs were dispersed homogenously among the LiMn0.6Fe0.4PO4@C active particles. The synergistic effect of the nanoscale amorphous carbon coated LiMn0.6Fe0.4PO4@C active particles and the graphitized CNTs reduces the diffusion path of the lithium ions and benefits the transference ability of electron.展开更多
The undesirable shuttle effect and sluggish redox kinetics of polysulfides seriously result in low sulfur utilization and poor capacity retention.Here,an integrated strategy is proposed by rational designing multifunc...The undesirable shuttle effect and sluggish redox kinetics of polysulfides seriously result in low sulfur utilization and poor capacity retention.Here,an integrated strategy is proposed by rational designing multifunctional architecture to manipulate the redox kinetics of polysulfides,specifically,by employing iron atoms(Fe-As)and iron-species nanoparticles(Fe-NPs)co-embedded nitrogen-doped carbon nanotube(Fe-NCNT)as catalyst and host for sulfur.The synergistic cooperation of Fe-As and Fe-NPs provides efficient active sites to facilitate the diffusion,strengthen the affinities,and promote the conversion reactions for polysulfides.Furthermore,the NCNT not only offers practical Li+transport pathways but also immobilize the polysulfides effectively.Benefiting from these merits,the Fe-NCNT/S electrodes exhibit high initial specific capacity of 1502.6 mAh/g at 0.1 C,outstanding rate performance(830 mAh/g at 2 C),and good cycling performance(597.8 mAh/g after 500 cycles with an ultralow capacity fading rate of 0.069%per cycle).This work features the distinct interaction of iron atom-nanoparticles on facilitating immobilization-diffusion-transformation process of polysulfides,and it also expected to pave the way for the application in practical Li-S batteries.展开更多
We demonstrated a method to fabricate functional hybrid film patches that were used to form Pickering emulsions （PEs）. The hybrid patches were made of carbon nanotubes, Fe3O4 nanoparticles, octadecyltrimethoxysilane...We demonstrated a method to fabricate functional hybrid film patches that were used to form Pickering emulsions （PEs）. The hybrid patches were made of carbon nanotubes, Fe3O4 nanoparticles, octadecyltrimethoxysilane, and poly（diallyldimethylammonium chloride）. The aqueous phase of the hybridpatch stabilized PEs can be easily separated by applying a magnetic field. The hybrid-film-patch stabilized PEs are extremely stable and lasted for eight months at room temperature. Furthermore, they are easily ruptured by adding ethanol, and regenerated by vortexing the patches in aqueous/oil mixtures, enabling the inner hydrophilic side of the patches to be easily modified with metal nanoparticles. As an example, palladium nanoparticles were embedded into the surface of the hybrid patches using an in situ reduction method. The Pd functionalized patch formed PEs showed an excellent catalytic performance for the hydrogenation of acetone with a yield of 99.5%. The same batch of Pd functionalized patches was recycled 13 times without loss of the catalytic activity. The hybrid-patch formed PEs have a great potential in the catalytic field.展开更多
基金supported by the National Natural Science Foundation of China(21421001,21573115,21875118)Tianjin Science and Technology Commission(18JCTPJC55900)+1 种基金the Natural Science Foundation of Tianjin(17JCYBJC17100,19JCZDJC37700)the 111 Project(B12015).
文摘The design and development of low-cost,efficient,and stable bifunctional electrocatalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desirable for rechargeable metal-air batteries.In this work,N-doped porous hollow carbon spheres encapsulated with ultrafine Fe/Fe3O4 nanoparticles(FeOx@N-PHCS)were fabricated by impregnation and subsequent pyrolysis,using melamine-formaldehyde resin spheres as self-sacrifice templates and polydopamine as N and C sources.The sufficient adsorption of Fe3+on the polydopamine endowed the formation of Fe-Nx species upon high-temperature carbonization.The prepared FeOx@N-PHCS has advanced features of large specific surface area,porous hollow structure,high content of N dopants,sufficient Fe-Nx species and ultrafine FeOx nanoparticles.These features endow FeOx@N-PHCS with enhanced mass transfer and considerable active sites,leading to high activity and stability in catalyzing ORR and OER in alkaline electrolyte.Furthermore,the rechargeable Zn-air battery with FeOx@N-PHCS as air cathode catalyst exhibits a large peak power density,narrow charge-discharge potential gap and robust cycling stability,demonstrating the potential of the fabricated FeOx@N-PHCS as a promising electrode material for metal-air batteries.This new finding may open an avenue for rational design of bifunctional catalysts by integrating different active components within all-in-one catalyst for different electrochemical reactions.
基金the National Natural Science Foundation of China(NSFC)(Nos.21501096 and 22075223)Natural Science Foundation of Jiangsu(Nos.BK20150086 and BK20201120)+2 种基金Foundation of the Jiangsu Education Committee(No.15KJB150020)the Six Talent Peaks Project in Jiangsu Province(No.JY-087)Innovation Project of Jiangsu Province.
文摘Interfacial atomic configuration between dual-metal active species and nitrogen-carbon substrates is of great importance for improving the intrinsic activity of catalysts toward oxygen reduction reaction(ORR).Thus,from the atomic-scale engineering we develop a high intrinsic activity ORR catalyst in terms of incorporating atomically dispersed dual Fe centers(single Fe atoms and ultra-small Fe atomic clusters)into bamboo-like N-doped carbon nanotubes.Benefiting from atomically dispersed dual-Fe centers on the atomic interface of Fe-Nx/carbon nanotubes,the fabricated dual Fe centers catalyst exhibits an extremely high ORR activity(E_(onset)=1.006 V;E_(1/2)=0.90 V),beyond state-of-the-art Pt/C.Remarkably,this catalyst also shows a superior kinetic current density of 19.690 mA·cm^(−2),which is 7 times that of state-of-the-art Pt/C.Additionally,based on the excellent catalyst,the primary Zn-air battery reveals a high power density up to 137 mW·cm^(−2) and sufficient potential cycling stability(at least 25 h).Undoubtedly,given the unique structure–activity relationship of dual-Fe active species and metal-nitrogen-carbon substrates,the catalyst will show great prospects in highly efficient electrochemical energy conversion devices.
基金funded by the National Natural Science Foundation of China(Grant Nos.21873067,21206117).
文摘The electrochemical conversion of CO_(2)-H_(2)O into CO-H_(2) using renewable energy is a promising technique for clean syngas production.Low-cost electrocatalysts to produce tunable syngas with a potential-independent CO/H_(2) ratio are highly desired.Herein,a series of N-doped carbon nanotubes encapsulating binary alloy nanoparticles(MxNi-NCNT,M=Fe,Co)were successfully fabricated through the co-pyrolysis of melamine and metal precursors.The MxNi-NCNT samples exhibited bamboo-like nanotubular structures with a large specific surface area and high degree of graphitization.Their electrocatalytic performance for syngas production can be tuned by changing the alloy compositions and modifying the electronic structure of the carbon nanotube through the encapsulated metal nanoparticles.Consequently,syngas with a wide range of CO/H_(2) ratios,from 0.5:1 to 3.4:1,can be produced on MxNi-NCNT.More importantly,stable CO/H_(2) ratios of 2:1 and 1.5:1,corresponding to the ratio to produce biofuels by syngas fermentation,could be realized on Co1Ni-NCNT and Co2Ni-NCNT,respectively,over a potential window of-0.8 to-1.2 V versus the reversible hydrogen electrode.Our work provides an approach to develop low-cost and potential-independent electrocatalysts to effectively produce syngas with an adjustable CO/H_(2) ratio from electrochemical CO_(2) reduction.
基金supported by the National Natural Science Foundation of China (No. 51474196)the Major State Basic Research Development Program of China (973 Program No. 2013CB934700)
文摘Three dimensional（3D） nano-LiMn0.6Fe0.4PO4@C/CNT composite was successfully synthesized by an oleylamine-assisted solvothermal method. The prepared composite showed excellent electrochemical performance, especially superior high rate capability. It could deliver a specific discharge capacity of103.1 mAh/g, even at 80 C. The superior high rate performance of the as-prepared LiMn0.6Fe0.4PO4@C/CNT electrode is attributed to its unique 3D conducting network：（1） the prepared LiMn0.6Fe0.4PO4@C active particles were in nano-scale with a size of 30-50 nm;（2） LiMn0.6Fe0.4PO4 nanoparticles were uniformly coated by amorphous carbon with a thickness of 3 nm;（3） the graphitized conductive CNTs were dispersed homogenously among the LiMn0.6Fe0.4PO4@C active particles. The synergistic effect of the nanoscale amorphous carbon coated LiMn0.6Fe0.4PO4@C active particles and the graphitized CNTs reduces the diffusion path of the lithium ions and benefits the transference ability of electron.
基金supported by the Natural Science Foundation of China(Nos.22125902,U2032202,21975243 and 21825302)the National Program for Support of Topnotch Young Professionals,the Fundamental Research Funds for the Central Universities(No.WK2030020032)+1 种基金the DNL cooperation Fund,CAS(No.DNL202020)the Anhui Science Fund for Distinguished Young Scholars(No.2208085J15).
文摘The undesirable shuttle effect and sluggish redox kinetics of polysulfides seriously result in low sulfur utilization and poor capacity retention.Here,an integrated strategy is proposed by rational designing multifunctional architecture to manipulate the redox kinetics of polysulfides,specifically,by employing iron atoms(Fe-As)and iron-species nanoparticles(Fe-NPs)co-embedded nitrogen-doped carbon nanotube(Fe-NCNT)as catalyst and host for sulfur.The synergistic cooperation of Fe-As and Fe-NPs provides efficient active sites to facilitate the diffusion,strengthen the affinities,and promote the conversion reactions for polysulfides.Furthermore,the NCNT not only offers practical Li+transport pathways but also immobilize the polysulfides effectively.Benefiting from these merits,the Fe-NCNT/S electrodes exhibit high initial specific capacity of 1502.6 mAh/g at 0.1 C,outstanding rate performance(830 mAh/g at 2 C),and good cycling performance(597.8 mAh/g after 500 cycles with an ultralow capacity fading rate of 0.069%per cycle).This work features the distinct interaction of iron atom-nanoparticles on facilitating immobilization-diffusion-transformation process of polysulfides,and it also expected to pave the way for the application in practical Li-S batteries.
基金This work was supported by the National Natural Science Foundation of China （Nos. 21273059 and 21003032）, State Key Laboratory of Urban Water Resource and Environment （Harbin Institute of Technology） （No. 2014DX09）, the Fundamental Research Funds for the Central Universities （No. HIT. KISTP. 201407）, and Harbin Science and Technology Research Council （No. 2014RFXXJ063）.
文摘We demonstrated a method to fabricate functional hybrid film patches that were used to form Pickering emulsions （PEs）. The hybrid patches were made of carbon nanotubes, Fe3O4 nanoparticles, octadecyltrimethoxysilane, and poly（diallyldimethylammonium chloride）. The aqueous phase of the hybridpatch stabilized PEs can be easily separated by applying a magnetic field. The hybrid-film-patch stabilized PEs are extremely stable and lasted for eight months at room temperature. Furthermore, they are easily ruptured by adding ethanol, and regenerated by vortexing the patches in aqueous/oil mixtures, enabling the inner hydrophilic side of the patches to be easily modified with metal nanoparticles. As an example, palladium nanoparticles were embedded into the surface of the hybrid patches using an in situ reduction method. The Pd functionalized patch formed PEs showed an excellent catalytic performance for the hydrogenation of acetone with a yield of 99.5%. The same batch of Pd functionalized patches was recycled 13 times without loss of the catalytic activity. The hybrid-patch formed PEs have a great potential in the catalytic field.
