Doping modification of electrode materials is a sought-after strategy to improve their electrochemical performance in the secondary batteries field. Herein,polyanion（BO3）^3-doped Li3V2（PO4）3 cathode materials were...Doping modification of electrode materials is a sought-after strategy to improve their electrochemical performance in the secondary batteries field. Herein,polyanion（BO3）^3-doped Li3V2（PO4）3 cathode materials were successfully synthesized via a wet coordination method. The effects of（BO3）^3- doping content on crystal structure, morphology and electrochemical performance were explored by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）. All the asprepared samples have the same monoclinic structure;among them, Li3V2（PO4）（2.75）（BO3）（0.15） sample has relatively uniform and optimized particle size. In addition, this sample has the highest discharge capacity and the best cycling stability, with an initial discharge capacity of 120.4mAh·g^-1, and after 30 cycles at a rate of 0.1C, the discharge capacity still remains 119.3 mAh·g^-1. It is confirmed that moderate polyanion（BO3）^3- doping can rearrange the electronic structure of the bulk Li3V2（PO4）3,lower the charge transfer resistance and further improve the electrochemical behaviors.展开更多
Based on monolayer dispersion theory,Co_(3)O_(4)/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ammonia.Co_(3)O_(4)can spontaneously disperse on HZSM...Based on monolayer dispersion theory,Co_(3)O_(4)/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ammonia.Co_(3)O_(4)can spontaneously disperse on HZSM-5 support with a monolayer dispersion threshold of 0.061 mmol 100 m^(-2),equaling to a weight percentage around 4.5%.It has been revealed that the quantities of surface active oxygen(O_(2)^(-))and acid sites are crucial for the reaction,which can adsorb and activate NO_(x)and NH_(3)reactants effectively.Below the monolayer dispersion threshold,Co_(3)O_(4)is finely dispersed as sub-monolayers or monolayers and in an amorphous state,which is favorable to generate the two kinds of active sites,hence promoting the performance of ammonia selective catalytic reduction of nitrogen oxide.However,the formation of crystalline Co_(3)O_(4)above the capacity is harmful to the reaction performance.4%Co_(3)O_(4)/ZSM-5,the catalyst close to the monolayer dispersion capacity,possesses the most abundant active O_(2)^(-)species and acidic sites,thereby demonstrating the best reaction performance in all the samples.It is proposed the optimal Co_(3)O_(4)/ZSM-5 catalyst can be prepared by loading the capacity amount of Co_(3)O_(4)onto HZSM-5 support.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0100500)the Beijing Co-construction Project(No.20150939014)
文摘Doping modification of electrode materials is a sought-after strategy to improve their electrochemical performance in the secondary batteries field. Herein,polyanion（BO3）^3-doped Li3V2（PO4）3 cathode materials were successfully synthesized via a wet coordination method. The effects of（BO3）^3- doping content on crystal structure, morphology and electrochemical performance were explored by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）. All the asprepared samples have the same monoclinic structure;among them, Li3V2（PO4）（2.75）（BO3）（0.15） sample has relatively uniform and optimized particle size. In addition, this sample has the highest discharge capacity and the best cycling stability, with an initial discharge capacity of 120.4mAh·g^-1, and after 30 cycles at a rate of 0.1C, the discharge capacity still remains 119.3 mAh·g^-1. It is confirmed that moderate polyanion（BO3）^3- doping can rearrange the electronic structure of the bulk Li3V2（PO4）3,lower the charge transfer resistance and further improve the electrochemical behaviors.
基金the financial supporting by the National Natural Science Foundation of China(Grant Nos.21962009,22172071,22102069,22062013)the Natural Science Foundation of Jiangxi Province(Grant Nos.20202BAB203006,20181ACB20005)the Key Laboratory Foundation of Jiangxi Province for Environment and Energy Catalysis(Grant No.20181BCD40004).
文摘Based on monolayer dispersion theory,Co_(3)O_(4)/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ammonia.Co_(3)O_(4)can spontaneously disperse on HZSM-5 support with a monolayer dispersion threshold of 0.061 mmol 100 m^(-2),equaling to a weight percentage around 4.5%.It has been revealed that the quantities of surface active oxygen(O_(2)^(-))and acid sites are crucial for the reaction,which can adsorb and activate NO_(x)and NH_(3)reactants effectively.Below the monolayer dispersion threshold,Co_(3)O_(4)is finely dispersed as sub-monolayers or monolayers and in an amorphous state,which is favorable to generate the two kinds of active sites,hence promoting the performance of ammonia selective catalytic reduction of nitrogen oxide.However,the formation of crystalline Co_(3)O_(4)above the capacity is harmful to the reaction performance.4%Co_(3)O_(4)/ZSM-5,the catalyst close to the monolayer dispersion capacity,possesses the most abundant active O_(2)^(-)species and acidic sites,thereby demonstrating the best reaction performance in all the samples.It is proposed the optimal Co_(3)O_(4)/ZSM-5 catalyst can be prepared by loading the capacity amount of Co_(3)O_(4)onto HZSM-5 support.
