CoSn alloy and Cu-Sn samples were syn thesized by H 2 -reduction following solid-state r eaction between Co ?,Cu?,Sn?and NaOH at ambient temperature.The samples were characterized by XRD,S EM.The results showed that C...CoSn alloy and Cu-Sn samples were syn thesized by H 2 -reduction following solid-state r eaction between Co ?,Cu?,Sn?and NaOH at ambient temperature.The samples were characterized by XRD,S EM.The results showed that CoSn alloy(80～200nm)is globe-shaped,ultrafine hexagon al material,and Cu-Sn alloy powder consists of two phases,i.e.Cu 6 Sn 5 and Cu 3 Sn.Cu-Sn powder has spherical morphology and the particle size is estimated to be 60～70nm.The electro chemical performances of CoSn alloy and Cu-Sn powder were studied using lithium-ions model cell Li /LiPF 6 (EC +DMC)/CoSn(or Cu-Sn).It was demonstrated the reversible discharge capacities for 10cycles keep above 280mAh ·g -1 for nanophase Cu-Sn,and 60mAh ·g -1 for CoSn alloy.Differ-ential capacity plots showed that th e reaction mechanisms of Cu-Sn with l ithium were reversible.展开更多
Due to its high theoretical capacity and appropriate potential platform,tin-based alloy materials are expected to be a competitive candidate for the next-generation high performance anodes of lithium-ion batteries.Nev...Due to its high theoretical capacity and appropriate potential platform,tin-based alloy materials are expected to be a competitive candidate for the next-generation high performance anodes of lithium-ion batteries.Nevertheless,the immense volume change during the lithium-ion insert process leads to severe disadvantages of structural damage and capacity fade,which limits its practical application.In this work,a three-dimensional(3 D)multicore-shell hollow nanobox encapsulated by carbon layer is obtained via a three-step method of hydrothermal reaction,annealing and alkali etching.During the electrochemical reactions,the CoSn@void@C nanoboxes provide internal space to compensate the volumetric change upon the lithiation of Sn,while the inactive component of Co acts as chemical buffers to withstand the anisotropic expansion of nanoparticles.Owing to the above-mentioned advantages,the elaborated anode delivers an excellent capacity of 788.2 m Ah/g at 100 m A/g after 100 cycles and considerable capacity retention of 519.2 mAh/g even at a high current density of 1 A/g after 300 cycles.The superior stability and high performance indicate its capability as promising anodes for lithium-ion batteries.展开更多
Highly active bifunctional oxygen electrocatalysts accelerate the development of high-performance Zn-air battery,but suffer from the mismatched activities of oxygen evolution reaction(OER)and oxygen reduced reaction(O...Highly active bifunctional oxygen electrocatalysts accelerate the development of high-performance Zn-air battery,but suffer from the mismatched activities of oxygen evolution reaction(OER)and oxygen reduced reaction(ORR).Herein,highly integrated bifunctional oxygen electrocatalysts,cobalt-tin alloys coated by nitrogen doped carbon(CoSn@NC)are prepared by MOFs-derived method.In this hybrid catalyst,the binary CoSn nanoalloys mainly contribute to highly active OER process while the Co(or Sn)-N-C serves as ORR active sites.Rational interaction between CoSn and NC donates more rapid reaction kinetics than Pt/C(ORR)and IrO_(2)(OER).Such CoSn@NC holds a promise as air-cathode electrocatalyst in Zn-air battery,superior to Pt/C+IrO_(2)catalyst.First-principles calculations predict that CoSn alloys can upgrade charge redistribution on NC and promote the transfer to reactants,thus optimizing the adsorption strength of oxygen-containing intermediates to boost the overall reactivity.The tuning of oxygenate adsorption by interactions between alloy and heteroatom-doped carbon can guide the design of bifunctional oxygen electrocatalysts.展开更多
The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled elec...The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled electron transfer(PCET)hinders the overall OER efficiency.Herein,we report an ionic liquid(IL)modified CoSn(OH)_(6)nanocubes(denoted as CoS-n(OH)_(6)-IL),which could be prepared through a facile strategy.The modified IL would not change the structural character-istics of CoSn(OH)_(6),but could effectively regulate the local proton activity near the active sites.The CoSn(OH)_(6)-IL exhibited higher intrinsic OER performances than the pristine CoSn(OH)_(6)in neutral media.For example,the current density of CoS-n(OH)_(6)-IL at 1.8 V versus reversible hydrogen electrode(RHE)was about 4 times higher than that of CoSn(OH)_(6).According to the pH-dependent kinetic investigations,operando electrochemical impedance spectroscopic,chemical probe tests,and deuterium kinetic isotope effects,the interfacial layer of IL could be utilized as a proton transfer mediator to promote the proton transfer,which enhances the surface coverage of OER intermediates and reduces the activation barrier.Consequent-ly,the sluggish OER kinetics would be efficiently accelerated.This study provides a facile and effective strategy to facilitate the PCET processes and is beneficial to guide the rational design of OER electrocatalysts.展开更多
文摘CoSn alloy and Cu-Sn samples were syn thesized by H 2 -reduction following solid-state r eaction between Co ?,Cu?,Sn?and NaOH at ambient temperature.The samples were characterized by XRD,S EM.The results showed that CoSn alloy(80～200nm)is globe-shaped,ultrafine hexagon al material,and Cu-Sn alloy powder consists of two phases,i.e.Cu 6 Sn 5 and Cu 3 Sn.Cu-Sn powder has spherical morphology and the particle size is estimated to be 60～70nm.The electro chemical performances of CoSn alloy and Cu-Sn powder were studied using lithium-ions model cell Li /LiPF 6 (EC +DMC)/CoSn(or Cu-Sn).It was demonstrated the reversible discharge capacities for 10cycles keep above 280mAh ·g -1 for nanophase Cu-Sn,and 60mAh ·g -1 for CoSn alloy.Differ-ential capacity plots showed that th e reaction mechanisms of Cu-Sn with l ithium were reversible.
基金the financial support by National Natural Science Foundation of China(Nos.U20A20123,51874357,52002405)Innovative Research Group of Hunan Provincial Natural Science Foundation of China(No.2019JJ10006)the support from the 100 Talented Program of Hunan Province and“Huxiang High-level Talents”Program(No.2019RS1007)。
文摘Due to its high theoretical capacity and appropriate potential platform,tin-based alloy materials are expected to be a competitive candidate for the next-generation high performance anodes of lithium-ion batteries.Nevertheless,the immense volume change during the lithium-ion insert process leads to severe disadvantages of structural damage and capacity fade,which limits its practical application.In this work,a three-dimensional(3 D)multicore-shell hollow nanobox encapsulated by carbon layer is obtained via a three-step method of hydrothermal reaction,annealing and alkali etching.During the electrochemical reactions,the CoSn@void@C nanoboxes provide internal space to compensate the volumetric change upon the lithiation of Sn,while the inactive component of Co acts as chemical buffers to withstand the anisotropic expansion of nanoparticles.Owing to the above-mentioned advantages,the elaborated anode delivers an excellent capacity of 788.2 m Ah/g at 100 m A/g after 100 cycles and considerable capacity retention of 519.2 mAh/g even at a high current density of 1 A/g after 300 cycles.The superior stability and high performance indicate its capability as promising anodes for lithium-ion batteries.
基金This work was financially supported by Shanghai Science and Technology Innovation Action Plan(Program No.20DZ1204400)the Key Research Program of Frontier Science,Chinese Academy of Sciences(Grant No.QYZDJSSW-JSC013).
文摘Highly active bifunctional oxygen electrocatalysts accelerate the development of high-performance Zn-air battery,but suffer from the mismatched activities of oxygen evolution reaction(OER)and oxygen reduced reaction(ORR).Herein,highly integrated bifunctional oxygen electrocatalysts,cobalt-tin alloys coated by nitrogen doped carbon(CoSn@NC)are prepared by MOFs-derived method.In this hybrid catalyst,the binary CoSn nanoalloys mainly contribute to highly active OER process while the Co(or Sn)-N-C serves as ORR active sites.Rational interaction between CoSn and NC donates more rapid reaction kinetics than Pt/C(ORR)and IrO_(2)(OER).Such CoSn@NC holds a promise as air-cathode electrocatalyst in Zn-air battery,superior to Pt/C+IrO_(2)catalyst.First-principles calculations predict that CoSn alloys can upgrade charge redistribution on NC and promote the transfer to reactants,thus optimizing the adsorption strength of oxygen-containing intermediates to boost the overall reactivity.The tuning of oxygenate adsorption by interactions between alloy and heteroatom-doped carbon can guide the design of bifunctional oxygen electrocatalysts.
基金supported by the National Natural Science Foundation of China(22209040,22202063).
文摘The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled electron transfer(PCET)hinders the overall OER efficiency.Herein,we report an ionic liquid(IL)modified CoSn(OH)_(6)nanocubes(denoted as CoS-n(OH)_(6)-IL),which could be prepared through a facile strategy.The modified IL would not change the structural character-istics of CoSn(OH)_(6),but could effectively regulate the local proton activity near the active sites.The CoSn(OH)_(6)-IL exhibited higher intrinsic OER performances than the pristine CoSn(OH)_(6)in neutral media.For example,the current density of CoS-n(OH)_(6)-IL at 1.8 V versus reversible hydrogen electrode(RHE)was about 4 times higher than that of CoSn(OH)_(6).According to the pH-dependent kinetic investigations,operando electrochemical impedance spectroscopic,chemical probe tests,and deuterium kinetic isotope effects,the interfacial layer of IL could be utilized as a proton transfer mediator to promote the proton transfer,which enhances the surface coverage of OER intermediates and reduces the activation barrier.Consequent-ly,the sluggish OER kinetics would be efficiently accelerated.This study provides a facile and effective strategy to facilitate the PCET processes and is beneficial to guide the rational design of OER electrocatalysts.
