Introducing catalytically-active Fe and N into carbon materials results in promising FeNC catalysts for oxygen reduction reaction. However, the doped Fe and N species are frequently subject to heavy loss in a traditio...Introducing catalytically-active Fe and N into carbon materials results in promising FeNC catalysts for oxygen reduction reaction. However, the doped Fe and N species are frequently subject to heavy loss in a traditional carbonization process owing to Fe agglomeration and evaporation of N-contained small molecules. Besides, pyrolysis may make materials sintering which embeds a large number of active sites in the bulk phase and impedes direct exposure of reactive centers to the reactants. We here report that when calcinations, the addition of ZnCl2, an ordinary salt with very wide melting temperature range well covering the carbonization process of the precursor iron porphyrin, can significantly enhance the doping level of the active species and simultaneously create highly porous structures for FeNC catalysts. The obtained FeNC demonstrates ultrahigh catalytic activities even significantly better than Pt/C in oxygen reduction reaction.展开更多
A series of transition metal nitrides(MxNy,M=Fe,Co,Ni)nanoparticle(NP)composites caged in N-doped hollow porous carbon sphere(NHPCS)were prepared by impregnation and heat treatment methods.These composites combine the...A series of transition metal nitrides(MxNy,M=Fe,Co,Ni)nanoparticle(NP)composites caged in N-doped hollow porous carbon sphere(NHPCS)were prepared by impregnation and heat treatment methods.These composites combine the high catalytic activity of nitrides and the high-efficiency mass transfer characteristics of NHPCS.The oxygen reduction reaction results indicate that Fe2N/NHPCS has the synergistic catalytic performance of higher onset potential(0.96 V),higher electron transfer number(~4)and higher limited current density(1.4 times as high as that of commercial Pt/C).In addition,this material is implemented as the air catalyst for zinc−air battery that exhibits considerable specific capacity(795.1 mA·h/g)comparable to that of Pt/C,higher durability and maximum power density(173.1 mW/cm2).展开更多
The rational design of efficient and stable carbon-based electrocatalysts for oxygen reduction and oxygen evolution reactions is crucial for improving energy density and long-term stability of rechargeable zinc-air ba...The rational design of efficient and stable carbon-based electrocatalysts for oxygen reduction and oxygen evolution reactions is crucial for improving energy density and long-term stability of rechargeable zinc-air batteries(ZABs).Herein,a general and controllable synthesis method was developed to prepare three-dimensional(3D)porous carbon composites embedded with diverse metal phosphide nanocrystallites by interfacial coordination of transition metal ions with phytic acid-doped polyaniline networks and subsequent pyrolysis.Phytic acid as the dopant of polyaniline provides favorable anchoring sites for metal ions owing to the coordination interaction.Specifically,adjusting the concentration of adsorbed cobalt ions can achieve the phase regulation of transition metal phosphides.Thus,with abundant cobalt phosphide nanoparticles and nitrogen-and phosphorus-doping sites,the obtained carbon-based electrocatalysts exhibited efficient electrocatalytic activities toward oxygen reduction and evolution reactions.Consequently,the fabricated ZABs exhibited a high energy density,high power density of 368 mW cm^(-2),and good cycling/mechanical stability,which could power water splitting for integrated device fabrication with high gas yields.展开更多
Reversible oxygen reaction plays a crucial role in rechargeable battery systems,but it is limited by the slow reaction kinetics.Herein,the ionic modulation of cobalt pentlandite coupled with nitrogen‐doped bowl‐like...Reversible oxygen reaction plays a crucial role in rechargeable battery systems,but it is limited by the slow reaction kinetics.Herein,the ionic modulation of cobalt pentlandite coupled with nitrogen‐doped bowl‐like hollow carbon sphere is well designed on octahedral and tetrahedral sites.The robust FexCo9−xS8‐NHCS‐V with iron replacing at the octahedron possesses prolonged metal sulfur bond and exhibits excellent bifunctional electrocatalytic performance towards oxygen reduction reaction(ORR,E_(1/2)=0.80 V vs.RHE)and excellent oxygen evolution reaction(OER,E_(j=10)=1.53 V vs.RHE)in 0.1 mol/L KOH.Accordingly,a rechargeable Zn‐air battery of Fe_(x)Co_(9−x)S_(8)‐NHCS‐V cathode endows high energy efficiency(102 mW cm^(−2)),and a microbial fuel cell achieves a high‐power density(791±42 mW m^(−2)),outperforming the benchmark Pt/C catalyst.展开更多
Although the application of various nonprecious compounds as the air cathodes of Zn-air batteries has been explored, the construction of highly efficient selfsupported Co-based electrodes remains challenging and highl...Although the application of various nonprecious compounds as the air cathodes of Zn-air batteries has been explored, the construction of highly efficient selfsupported Co-based electrodes remains challenging and highly desired given their outstanding electrocatalytic activity and cost-effectiveness. Herein, we fabricated a three-dimensional(3D) self-supported electrode based on N-doped,carbon-coated Co3O4 nanosheets grown on a carbon cloth(i.e., NC-Co3O4/CC) through the electrochemical deposition and carbonization. When used as a binder-free electrode for oxygen evolution reaction(OER), the NC–Co3O4/CC electrode demonstrated excellent electrocatalytic activity with an overpotential of 210 mV at 10 mA cm^-2 and a Tafel slope of79.6 mV dec^-1. In the Zn-air battery test, the electrode delivered a small charge/discharge voltage gap(0.87 V at 10 mA cm^-2) and exhibited high durability without degradation after 93 cycles at the large current density of 25 mA cm^-2.The durability of our electrode was superior to that of a commercial Pt/C+RuO2 catalyst. The excellent performance of NC–Co3O4/CC could be attributed to the presence of 3D structures that promoted electron/ion transfer. By the absence of a binder, the carbon coating improved electron conductivity and promoted electrochemical stability. Moreover, N doping could be used to adjust the C electron structure and accelerate electron transfer. The present study provides a facile and effective route for the synthesis of various self-supported electrodes that fulfill the requirements of different energy storage and conversion devices.展开更多
文摘Introducing catalytically-active Fe and N into carbon materials results in promising FeNC catalysts for oxygen reduction reaction. However, the doped Fe and N species are frequently subject to heavy loss in a traditional carbonization process owing to Fe agglomeration and evaporation of N-contained small molecules. Besides, pyrolysis may make materials sintering which embeds a large number of active sites in the bulk phase and impedes direct exposure of reactive centers to the reactants. We here report that when calcinations, the addition of ZnCl2, an ordinary salt with very wide melting temperature range well covering the carbonization process of the precursor iron porphyrin, can significantly enhance the doping level of the active species and simultaneously create highly porous structures for FeNC catalysts. The obtained FeNC demonstrates ultrahigh catalytic activities even significantly better than Pt/C in oxygen reduction reaction.
基金the National Natural Science Foundation of China(Nos.51702137,51802128)the Natural Science Foundation of Jiangsu Province,China(No.BK20181013)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(No.18KJB430013)the Foundation of State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering,China(No.2020-KF-20).
文摘A series of transition metal nitrides(MxNy,M=Fe,Co,Ni)nanoparticle(NP)composites caged in N-doped hollow porous carbon sphere(NHPCS)were prepared by impregnation and heat treatment methods.These composites combine the high catalytic activity of nitrides and the high-efficiency mass transfer characteristics of NHPCS.The oxygen reduction reaction results indicate that Fe2N/NHPCS has the synergistic catalytic performance of higher onset potential(0.96 V),higher electron transfer number(~4)and higher limited current density(1.4 times as high as that of commercial Pt/C).In addition,this material is implemented as the air catalyst for zinc−air battery that exhibits considerable specific capacity(795.1 mA·h/g)comparable to that of Pt/C,higher durability and maximum power density(173.1 mW/cm2).
文摘The rational design of efficient and stable carbon-based electrocatalysts for oxygen reduction and oxygen evolution reactions is crucial for improving energy density and long-term stability of rechargeable zinc-air batteries(ZABs).Herein,a general and controllable synthesis method was developed to prepare three-dimensional(3D)porous carbon composites embedded with diverse metal phosphide nanocrystallites by interfacial coordination of transition metal ions with phytic acid-doped polyaniline networks and subsequent pyrolysis.Phytic acid as the dopant of polyaniline provides favorable anchoring sites for metal ions owing to the coordination interaction.Specifically,adjusting the concentration of adsorbed cobalt ions can achieve the phase regulation of transition metal phosphides.Thus,with abundant cobalt phosphide nanoparticles and nitrogen-and phosphorus-doping sites,the obtained carbon-based electrocatalysts exhibited efficient electrocatalytic activities toward oxygen reduction and evolution reactions.Consequently,the fabricated ZABs exhibited a high energy density,high power density of 368 mW cm^(-2),and good cycling/mechanical stability,which could power water splitting for integrated device fabrication with high gas yields.
文摘Reversible oxygen reaction plays a crucial role in rechargeable battery systems,but it is limited by the slow reaction kinetics.Herein,the ionic modulation of cobalt pentlandite coupled with nitrogen‐doped bowl‐like hollow carbon sphere is well designed on octahedral and tetrahedral sites.The robust FexCo9−xS8‐NHCS‐V with iron replacing at the octahedron possesses prolonged metal sulfur bond and exhibits excellent bifunctional electrocatalytic performance towards oxygen reduction reaction(ORR,E_(1/2)=0.80 V vs.RHE)and excellent oxygen evolution reaction(OER,E_(j=10)=1.53 V vs.RHE)in 0.1 mol/L KOH.Accordingly,a rechargeable Zn‐air battery of Fe_(x)Co_(9−x)S_(8)‐NHCS‐V cathode endows high energy efficiency(102 mW cm^(−2)),and a microbial fuel cell achieves a high‐power density(791±42 mW m^(−2)),outperforming the benchmark Pt/C catalyst.
基金the support from the National Natural Science Foundation of China (21631004, 21771059 and 21571054)Heilongjiang Provincial Postdoctoral Science Foundation (LBH-Q16194)
文摘Although the application of various nonprecious compounds as the air cathodes of Zn-air batteries has been explored, the construction of highly efficient selfsupported Co-based electrodes remains challenging and highly desired given their outstanding electrocatalytic activity and cost-effectiveness. Herein, we fabricated a three-dimensional(3D) self-supported electrode based on N-doped,carbon-coated Co3O4 nanosheets grown on a carbon cloth(i.e., NC-Co3O4/CC) through the electrochemical deposition and carbonization. When used as a binder-free electrode for oxygen evolution reaction(OER), the NC–Co3O4/CC electrode demonstrated excellent electrocatalytic activity with an overpotential of 210 mV at 10 mA cm^-2 and a Tafel slope of79.6 mV dec^-1. In the Zn-air battery test, the electrode delivered a small charge/discharge voltage gap(0.87 V at 10 mA cm^-2) and exhibited high durability without degradation after 93 cycles at the large current density of 25 mA cm^-2.The durability of our electrode was superior to that of a commercial Pt/C+RuO2 catalyst. The excellent performance of NC–Co3O4/CC could be attributed to the presence of 3D structures that promoted electron/ion transfer. By the absence of a binder, the carbon coating improved electron conductivity and promoted electrochemical stability. Moreover, N doping could be used to adjust the C electron structure and accelerate electron transfer. The present study provides a facile and effective route for the synthesis of various self-supported electrodes that fulfill the requirements of different energy storage and conversion devices.
