Electrocatalytic oxygen reduction via a two-electron pathway(2e^(-)-ORR)is a promising and eco-friendly route for producing hydrogen peroxide(H_(2)O_(2)).Single-atom catalysts(SACs)typically show excellent selectivity...Electrocatalytic oxygen reduction via a two-electron pathway(2e^(-)-ORR)is a promising and eco-friendly route for producing hydrogen peroxide(H_(2)O_(2)).Single-atom catalysts(SACs)typically show excellent selectivity towards 2e^(-)-ORR due to their unique electronic structures and geometrical configurations.The very low density of single-atom active centers,however,often leads to unsatisfactory H_(2)O_(2)yield rate,significantly inhibiting their practical feasibility.Addressing this,we herein introduce fluorine as a secondary doping element into conventional SACs,which does not directly coordinate with the singleatom metal centers but synergize with them in a remote manner.This strategy effectively activates the surrounding carbon atoms and converts them into highly active sites for 2e^(-)-ORR.Consequently,a record-high H_(2)O_(2)yield rate up to 27 mol g^(-1)h^(-1)has been achieved on the Mo–F–C catalyst,with high Faradaic efficiency of 90%.Density functional theory calculations further confirm the very kinetically facile 2e^(-)-ORR over these additional active sites and the superiority of Mo as the single-atom center to others.This strategy thus not only provides a high-performance electrocatalyst for 2e^(-)-ORR but also should shed light on new strategies to significantly increase the active centers number of SACs.展开更多
Zinc-ion batteries(ZIBs)possess great advantages in terms of high safety and low cost,and are regarded as promising alternatives to lithium-ion batteries(LIBs).However,limited by the electrochemical kinetics and struc...Zinc-ion batteries(ZIBs)possess great advantages in terms of high safety and low cost,and are regarded as promising alternatives to lithium-ion batteries(LIBs).However,limited by the electrochemical kinetics and structural stability of the typical cathode materials,it is still difficult to simultaneously achieve high rates and high cycling stability for ZIBs.Herein,we present a manganese oxide(Sn_(x)Mn O_(2)/Sn O_(2))material that is dual-modified by Sn O_(2)/Mn O_(2)heterostructures and pre-intercalated Sn;cations as the cathode material for ZIBs.Such modification provides sufficient hetero-interfaces and expanded interlayer spacing in the material,which greatly facilitates the insertion/extraction of Zn^(2+).Meanwhile,the“structural pillars”of Sn^(4+) cations and the“pinning effect”of SnO_(2)also structurally stabilizes the Mn O_(2)species during the repeated Zn^(2+) insertion/extraction,leading to ultra-high cycling stability.Due to these merits,the Sn_(x)MnO_(2)/SnO_(2)cathode exhibits a high reversible capacity of 316.1 m Ah g^(-1) at 0.3 A g^(-1),superior rate capability of 179.4 m Ah g^(-1) at 2 A g^(-1),and 92.4%capacity retention after 2000 cycles.Consequently,this work would provide a promising yet efficient strategy by combining heterostructures and cations preintercalation to obtain high-performance cathodes for ZIBs.展开更多
Core-shell Bi-Bi2 O3/CNT(carbon nanotube) with 3-dimensional neural network structure where Bi-Bi2O3 nanospheres act as cell bodies supported by a 3-dimensional network of CNTs acting as synapses is designed and prepa...Core-shell Bi-Bi2 O3/CNT(carbon nanotube) with 3-dimensional neural network structure where Bi-Bi2O3 nanospheres act as cell bodies supported by a 3-dimensional network of CNTs acting as synapses is designed and prepared by simple solvothermal method and subsequent annealing autoreduction treatment,and this structure facilitates the efficient transport of electrons.It can provide two electron transfer paths due to the double contact of Bi2O3 shell with CNT and metal Bi core which enhances the efficiency of the electrochemical reaction.The Bi-Bi2 O3/CNT electrode shows a high gravimetric capacitance of 850 F g-1(1 A g-1),and the specific capacitance of Bi-Bi2O3/CNT can be still 714 F g-1 at 30 A g-1 indicating excellent rate performance.The asymmetric supercapacitor is assembled with Bi-Bi2 O3/CNT as the negative electrode and Ni(OH)2/CNT as the positive electrode,delivering a high energy density of 36.7 Wh kg-1 and a maximum power density of 8000 W kg-1.Therefore,the core-shell Bi-Bi2O3/CNT with 3-dimensional neural network structure as the negative electrode of supercapacitor shows great potential in the field of energy storage in the future.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22179093 and 21905202)。
文摘Electrocatalytic oxygen reduction via a two-electron pathway(2e^(-)-ORR)is a promising and eco-friendly route for producing hydrogen peroxide(H_(2)O_(2)).Single-atom catalysts(SACs)typically show excellent selectivity towards 2e^(-)-ORR due to their unique electronic structures and geometrical configurations.The very low density of single-atom active centers,however,often leads to unsatisfactory H_(2)O_(2)yield rate,significantly inhibiting their practical feasibility.Addressing this,we herein introduce fluorine as a secondary doping element into conventional SACs,which does not directly coordinate with the singleatom metal centers but synergize with them in a remote manner.This strategy effectively activates the surrounding carbon atoms and converts them into highly active sites for 2e^(-)-ORR.Consequently,a record-high H_(2)O_(2)yield rate up to 27 mol g^(-1)h^(-1)has been achieved on the Mo–F–C catalyst,with high Faradaic efficiency of 90%.Density functional theory calculations further confirm the very kinetically facile 2e^(-)-ORR over these additional active sites and the superiority of Mo as the single-atom center to others.This strategy thus not only provides a high-performance electrocatalyst for 2e^(-)-ORR but also should shed light on new strategies to significantly increase the active centers number of SACs.
基金supported by the National Natural Science Foundation of China(21905202 and 22002107)。
文摘Zinc-ion batteries(ZIBs)possess great advantages in terms of high safety and low cost,and are regarded as promising alternatives to lithium-ion batteries(LIBs).However,limited by the electrochemical kinetics and structural stability of the typical cathode materials,it is still difficult to simultaneously achieve high rates and high cycling stability for ZIBs.Herein,we present a manganese oxide(Sn_(x)Mn O_(2)/Sn O_(2))material that is dual-modified by Sn O_(2)/Mn O_(2)heterostructures and pre-intercalated Sn;cations as the cathode material for ZIBs.Such modification provides sufficient hetero-interfaces and expanded interlayer spacing in the material,which greatly facilitates the insertion/extraction of Zn^(2+).Meanwhile,the“structural pillars”of Sn^(4+) cations and the“pinning effect”of SnO_(2)also structurally stabilizes the Mn O_(2)species during the repeated Zn^(2+) insertion/extraction,leading to ultra-high cycling stability.Due to these merits,the Sn_(x)MnO_(2)/SnO_(2)cathode exhibits a high reversible capacity of 316.1 m Ah g^(-1) at 0.3 A g^(-1),superior rate capability of 179.4 m Ah g^(-1) at 2 A g^(-1),and 92.4%capacity retention after 2000 cycles.Consequently,this work would provide a promising yet efficient strategy by combining heterostructures and cations preintercalation to obtain high-performance cathodes for ZIBs.
文摘Core-shell Bi-Bi2 O3/CNT(carbon nanotube) with 3-dimensional neural network structure where Bi-Bi2O3 nanospheres act as cell bodies supported by a 3-dimensional network of CNTs acting as synapses is designed and prepared by simple solvothermal method and subsequent annealing autoreduction treatment,and this structure facilitates the efficient transport of electrons.It can provide two electron transfer paths due to the double contact of Bi2O3 shell with CNT and metal Bi core which enhances the efficiency of the electrochemical reaction.The Bi-Bi2 O3/CNT electrode shows a high gravimetric capacitance of 850 F g-1(1 A g-1),and the specific capacitance of Bi-Bi2O3/CNT can be still 714 F g-1 at 30 A g-1 indicating excellent rate performance.The asymmetric supercapacitor is assembled with Bi-Bi2 O3/CNT as the negative electrode and Ni(OH)2/CNT as the positive electrode,delivering a high energy density of 36.7 Wh kg-1 and a maximum power density of 8000 W kg-1.Therefore,the core-shell Bi-Bi2O3/CNT with 3-dimensional neural network structure as the negative electrode of supercapacitor shows great potential in the field of energy storage in the future.
