Heteroatom-doped carbon-based transition-metal single-atom catalysts(SACs) are promising electrocatalysts for oxygen reduction reaction(ORR). Herein, with the aid of hierarchically porous silica as hard template, a fa...Heteroatom-doped carbon-based transition-metal single-atom catalysts(SACs) are promising electrocatalysts for oxygen reduction reaction(ORR). Herein, with the aid of hierarchically porous silica as hard template, a facile and general melting perfusion and mesopore-confined pyrolysis method was reported to prepare single-atomic Fe/N–S-doped carbon catalyst(FeNx/NC-S) with hierarchically porous structure and well-defined morphology. The FeNx/NC-S exhibited excellent ORR activity with a half-wave potential(E_(1/2)) of 0.92 V, and a lower overpotential of 320 mV at a current density of 10 mA cm^(-2)for OER under alkaline condition. The remarkable electrocatalysis performance can be attributed to the hierarchically porous carbon nanospheres with S doping and high content of Fe-Nx sites(up to 3.7 wt% of Fe), resulting from the nano-confinement effect of the hierarchically porous silica spheres(NKM-5) during the pyrolysis process. The rechargeable Zn-air battery with FeNx/NC-S as a cathode catalyst demonstrated a superior power density of 194.5 mW cm-2charge–discharge stability. This work highlights a new avenue to design advanced SACs for efficient sustainable energy storage and conversion.展开更多
Fe-NX/C electrocatalysts have aroused extensive interest in accelerating sluggish oxygen reduction reaction (ORR) kinetics as potential alternatives to platinum catalysts in rechargeable Zn-air batteries (ZABs).Howeve...Fe-NX/C electrocatalysts have aroused extensive interest in accelerating sluggish oxygen reduction reaction (ORR) kinetics as potential alternatives to platinum catalysts in rechargeable Zn-air batteries (ZABs).However,the low density and poor accessibility of Fe-NXsites have severely restricted the electrocatalytic performance of Fe-NX/C.Herein,Fe,N co-doped ordered mesoporous carbon fiber bundles are prepared through a ligand-assisted strategy with nitrogen-rich 1,10-phenanthroline as space isolation agent.1,10-Phenanthroline reveals a six-membered heterocyclic structure containing abundant nitrogen species to tightly coordinate with Fe ions,which is conducive to achieving high-density Fe-NXsites.Meanwhile,the adoption of SBA-15 as hard-templates enables the catalysts with highly ordered channels and large specific surface areas,improving the accessibility of Fe-NXsites.The optimal catalyst (PDA-Fe-900) demonstrates a positive half-wave potential of 0.84 V (vs.RHE) in alkaline solution,outperforming the commercial Pt/C (0.83 V).In addition,PDA-Fe-900 delivers comparable ORR performance to commercial Pt/C in acidic electrolyte.Impressively,when PDA-Fe-900 is employed as an air cathode,it achieves large power densities of 163.0 m W/cm^(2) in liquid-state ZAB and 116.6 m W/cm^(2) in the flexible solid-state ZAB.This work provides an efficient ligand-assisted pathway for fabricating catalysts with dense and accessible FeNXsites as high-performance ORR electrocatalysts for ZABs.展开更多
Rational design of high-efficient and low-cost catalysts as alternatives to Pt-based catalysts toward the oxygen reduction reaction(ORR)is extremely desirable but challenging.In this work,Fe@NCNT is firstly synthesize...Rational design of high-efficient and low-cost catalysts as alternatives to Pt-based catalysts toward the oxygen reduction reaction(ORR)is extremely desirable but challenging.In this work,Fe@NCNT is firstly synthesized via the one-pot pyrolysis method,then Fe-NX active species are in-situ created on the prepared Fe@NCNT by a feasible“plasma inducing”strategy to synthesize the resulting catalyst(Fe@NCNT-P)for ORR.The morphology of Fe@NCNT-P is perfectly inherited by the derived carbon precursor,resulting in the core-shell structure of carboncoated Fe and a mesoporous dominant nanostructure with a high specific surface area of 536 m^(2)g^(-1).The resultant Fe@NCNT-P catalyst exhibits remarkable ORR activity and durability,as well as outstanding performance in assembled zinc-air battery(ZAB)test with a peak power density of 240 mW cm^(-2).This work not only reports a novel and robust ORR catalyst,but also proposes a simple and effective strategy to improve the ORR electrocatalytic performance.展开更多
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
Air cathodes with high electrocatalytic activity are vital for developing H2/O_(2) proton exchange membrane fuel cells(PEMFC)and Zn-air batteries.However,the state-of-the-art air cathodes suffer from either limited ca...Air cathodes with high electrocatalytic activity are vital for developing H2/O_(2) proton exchange membrane fuel cells(PEMFC)and Zn-air batteries.However,the state-of-the-art air cathodes suffer from either limited catalytic activity or high cost,which thus hinder their applications.Herein,we designed ZIF-8 derived nitrogen and atomic iron dual-doped porous carbon nanocubes as high-quality catalysts for ORR,through a novel gas-doping approach.The porous carbon nanocubic architecture and abundant Fe-Nxactive species endow ZIF-8 derived single atomic iron catalyst(PCN-A@Fe SA)with superior catalytic activity,and surpass Pt/C and a majority of the reported catalysts.Both XAS and DFT calculations suggest that Fe2+N4 moieties are the main active centers that are favorable for oxygen affinity and OH*intermediate desorption,which can result in promising catalytic performance.Most importantly,PCNA@Fe SA can achieve power density of 514 m W cm^(-2) as cathodic catalyst in a PEMFC and discharge peak power density of 185 m W cm^(-2) in an alkaline Zn-air battery.The outstanding performance is derived from both the high specific surface area and high-density of iron single atom in nitrogen doped nanocubic carbon matrix.展开更多
Highly active Fe-N_x sites that effectively improve the performance of non-precious metal electrocatalysts for oxygen reduction reactions（ORRs） are desirable. Herein, we propose a strategy for introducing a carbon t...Highly active Fe-N_x sites that effectively improve the performance of non-precious metal electrocatalysts for oxygen reduction reactions（ORRs） are desirable. Herein, we propose a strategy for introducing a carbon template into a melamine/Fe-salt mixture to inductively generate highly active Fe-N_x sites for ORR. Using 57 Fe M？sbauer spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, we studied the structural composition of the Fe and N co-doped carbon catalysts.Interestingly, the results showed that this system not only converted inactive Fe and Fe-carbides into active Fe-N_4 and other Fe-nitrides, but also improved their intrinsic activities.展开更多
The development of efficient transition metal oxygen reduction reaction(ORR)catalysts as substitutes for platinumbased catalysts has served as a key strategy in advancing the commercialization of fuel cells.Herein,an ...The development of efficient transition metal oxygen reduction reaction(ORR)catalysts as substitutes for platinumbased catalysts has served as a key strategy in advancing the commercialization of fuel cells.Herein,an effective Fe-N-C catalyst for the ORR was fabricated with hemin as the iron source of Fe-NX active sites through a simple precipitation-pyrolysis method.With the aid of hemin,the leaf-like ZIF-8 synthesized in an aqueous environment can be driven to transform into a stable three-dimensional dodecahedral structure,resulting in a substantial increase in the yield of Fe-N-C materials.Meanwhile,the influence of hemin loading in the precursors and pyrolysis temperature on the oxygen reduction catalytic activity of the final product Fe-N-C was investigated.Concretely,the optimal Fe100-N-C950 displays an onset potential of 1.054 V(vs.RHE)and a half-wave potential of 0.847 V(vs.RHE).Additionally,the direct ethanol fuel cell(DEFC)with Fe100-N-C950 as the cathode catalyst demonstrated a higher power density than the one with the commercial Pt-C catalyst.展开更多
基金supported by National Natural Science Foundation of China (21773128)。
文摘Heteroatom-doped carbon-based transition-metal single-atom catalysts(SACs) are promising electrocatalysts for oxygen reduction reaction(ORR). Herein, with the aid of hierarchically porous silica as hard template, a facile and general melting perfusion and mesopore-confined pyrolysis method was reported to prepare single-atomic Fe/N–S-doped carbon catalyst(FeNx/NC-S) with hierarchically porous structure and well-defined morphology. The FeNx/NC-S exhibited excellent ORR activity with a half-wave potential(E_(1/2)) of 0.92 V, and a lower overpotential of 320 mV at a current density of 10 mA cm^(-2)for OER under alkaline condition. The remarkable electrocatalysis performance can be attributed to the hierarchically porous carbon nanospheres with S doping and high content of Fe-Nx sites(up to 3.7 wt% of Fe), resulting from the nano-confinement effect of the hierarchically porous silica spheres(NKM-5) during the pyrolysis process. The rechargeable Zn-air battery with FeNx/NC-S as a cathode catalyst demonstrated a superior power density of 194.5 mW cm-2charge–discharge stability. This work highlights a new avenue to design advanced SACs for efficient sustainable energy storage and conversion.
基金supported by the National Natural Science Foundation of China(No.U1804255)the Key Research&Development and Promotion Projects in Henan Province(Nos.222102520038 and 212102210651)。
文摘Fe-NX/C electrocatalysts have aroused extensive interest in accelerating sluggish oxygen reduction reaction (ORR) kinetics as potential alternatives to platinum catalysts in rechargeable Zn-air batteries (ZABs).However,the low density and poor accessibility of Fe-NXsites have severely restricted the electrocatalytic performance of Fe-NX/C.Herein,Fe,N co-doped ordered mesoporous carbon fiber bundles are prepared through a ligand-assisted strategy with nitrogen-rich 1,10-phenanthroline as space isolation agent.1,10-Phenanthroline reveals a six-membered heterocyclic structure containing abundant nitrogen species to tightly coordinate with Fe ions,which is conducive to achieving high-density Fe-NXsites.Meanwhile,the adoption of SBA-15 as hard-templates enables the catalysts with highly ordered channels and large specific surface areas,improving the accessibility of Fe-NXsites.The optimal catalyst (PDA-Fe-900) demonstrates a positive half-wave potential of 0.84 V (vs.RHE) in alkaline solution,outperforming the commercial Pt/C (0.83 V).In addition,PDA-Fe-900 delivers comparable ORR performance to commercial Pt/C in acidic electrolyte.Impressively,when PDA-Fe-900 is employed as an air cathode,it achieves large power densities of 163.0 m W/cm^(2) in liquid-state ZAB and 116.6 m W/cm^(2) in the flexible solid-state ZAB.This work provides an efficient ligand-assisted pathway for fabricating catalysts with dense and accessible FeNXsites as high-performance ORR electrocatalysts for ZABs.
基金This work was supported by the National Natural Science Foundation of China(22109034,22109035,52164028,62105083)the Opening Project of Key Laboratory of Electrochemical Energy Storage and Energy Conversion of Hainan Province(KFKT2021007)the Foundation of State Key Laboratory of Marine Resource Utilization in South China Sea(Hainan University,MRUKF2021029).
文摘Rational design of high-efficient and low-cost catalysts as alternatives to Pt-based catalysts toward the oxygen reduction reaction(ORR)is extremely desirable but challenging.In this work,Fe@NCNT is firstly synthesized via the one-pot pyrolysis method,then Fe-NX active species are in-situ created on the prepared Fe@NCNT by a feasible“plasma inducing”strategy to synthesize the resulting catalyst(Fe@NCNT-P)for ORR.The morphology of Fe@NCNT-P is perfectly inherited by the derived carbon precursor,resulting in the core-shell structure of carboncoated Fe and a mesoporous dominant nanostructure with a high specific surface area of 536 m^(2)g^(-1).The resultant Fe@NCNT-P catalyst exhibits remarkable ORR activity and durability,as well as outstanding performance in assembled zinc-air battery(ZAB)test with a peak power density of 240 mW cm^(-2).This work not only reports a novel and robust ORR catalyst,but also proposes a simple and effective strategy to improve the ORR electrocatalytic performance.
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supported by the National Natural Science Foundation of China(NSFC Project Nos.21776104,21476088)the National Key Research and Development Program of China(Project Nos.2016YFB0101201,2017YFB0102900)+1 种基金the Guangdong Provincial Department of Science and Technology(Project No.2015B010106012)the Guangzhou Science,Technology and Innovation Committee(Project Nos.201504281614372,2016GJ006)。
文摘Air cathodes with high electrocatalytic activity are vital for developing H2/O_(2) proton exchange membrane fuel cells(PEMFC)and Zn-air batteries.However,the state-of-the-art air cathodes suffer from either limited catalytic activity or high cost,which thus hinder their applications.Herein,we designed ZIF-8 derived nitrogen and atomic iron dual-doped porous carbon nanocubes as high-quality catalysts for ORR,through a novel gas-doping approach.The porous carbon nanocubic architecture and abundant Fe-Nxactive species endow ZIF-8 derived single atomic iron catalyst(PCN-A@Fe SA)with superior catalytic activity,and surpass Pt/C and a majority of the reported catalysts.Both XAS and DFT calculations suggest that Fe2+N4 moieties are the main active centers that are favorable for oxygen affinity and OH*intermediate desorption,which can result in promising catalytic performance.Most importantly,PCNA@Fe SA can achieve power density of 514 m W cm^(-2) as cathodic catalyst in a PEMFC and discharge peak power density of 185 m W cm^(-2) in an alkaline Zn-air battery.The outstanding performance is derived from both the high specific surface area and high-density of iron single atom in nitrogen doped nanocubic carbon matrix.
文摘Highly active Fe-N_x sites that effectively improve the performance of non-precious metal electrocatalysts for oxygen reduction reactions（ORRs） are desirable. Herein, we propose a strategy for introducing a carbon template into a melamine/Fe-salt mixture to inductively generate highly active Fe-N_x sites for ORR. Using 57 Fe M？sbauer spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, we studied the structural composition of the Fe and N co-doped carbon catalysts.Interestingly, the results showed that this system not only converted inactive Fe and Fe-carbides into active Fe-N_4 and other Fe-nitrides, but also improved their intrinsic activities.
基金supported by the National Natural Science Foundation of China(Grant Nos.52106110,52306099)the Frontier Interdisciplinary Field Cultivation Special Fund of Xi’an University of Architecture and Technology(Grant No.X20240114)+1 种基金the Shaanxi Province Technical Innovation Guidance Special Project(Grant No.2023GXLH-051)the Youth Innovation Team of Shaanxi Universities.
文摘The development of efficient transition metal oxygen reduction reaction(ORR)catalysts as substitutes for platinumbased catalysts has served as a key strategy in advancing the commercialization of fuel cells.Herein,an effective Fe-N-C catalyst for the ORR was fabricated with hemin as the iron source of Fe-NX active sites through a simple precipitation-pyrolysis method.With the aid of hemin,the leaf-like ZIF-8 synthesized in an aqueous environment can be driven to transform into a stable three-dimensional dodecahedral structure,resulting in a substantial increase in the yield of Fe-N-C materials.Meanwhile,the influence of hemin loading in the precursors and pyrolysis temperature on the oxygen reduction catalytic activity of the final product Fe-N-C was investigated.Concretely,the optimal Fe100-N-C950 displays an onset potential of 1.054 V(vs.RHE)and a half-wave potential of 0.847 V(vs.RHE).Additionally,the direct ethanol fuel cell(DEFC)with Fe100-N-C950 as the cathode catalyst demonstrated a higher power density than the one with the commercial Pt-C catalyst.
