A series of single-phase double perovskite Pr1-xGdxBaCo_(2)-yFeyO_(5+σ)(x=0,0.5 and 1,0≤y≤1)materials were engineered through A/B site co-doping strategy to improve the mechanical,electrical and electrochemical pro...A series of single-phase double perovskite Pr1-xGdxBaCo_(2)-yFeyO_(5+σ)(x=0,0.5 and 1,0≤y≤1)materials were engineered through A/B site co-doping strategy to improve the mechanical,electrical and electrochemical properties as potential cathode materials for the application of intermediate solid oxide fuel cells(IT-SOFCs).The corresponding thermochemical stability,thermal expansion behavior,electrical conductivity and cathodic polarization resistance of the materials were systematically investigated.It was found that the A-site dual lanthanide doped Pr_(0.5)Gd_(0.5)BaCo_(2)O_(5+σ)(PGBCO)exhibits improved electrical conductivity,reduced thermal expansion,and comparatively low electrochemical polarization resistance versus single lanthanide double perovskite,PrBaCo_(2)O_(5+σ)(PBCO)and GdBaCo_(2)O_(5+σ)(GBCO)materials.Further investigation on the effect of B-site Fe-doping on Pr_(0.5)Gd_(0.5)BaCo_(2)-yFeyO_(5)+σ(PGBCF-y,0≤y≤1)reveals that all the PGBCF-y compositions exhibit excellent chemical stability with Gd-doped ceria(GDC)at operating temperatures not higher than 1100℃.Besides,doping of Fe in B-site can effectively reduce the thermal expansion coefficients(TECs)of the Pr_(0.5)Gd_(0.5)BaCo_(2)O_(5)+σceramics at 30e1000℃.And the electrochemical impedance spectra(EIS)results show that the PGBCF-y|GDC|PGBCF-y symmetric cells have acceptable low area specific polarization resistances.Further examination of the cathodic polarization and characteristic capacitance from the AC impedance spectra by employing the relaxation time distribution(DRT)method demonstrated that charge transfer is the dominating subprocess for the oxygen transport through the materials.展开更多
Developing hydrogen evolution reaction(HER)electrocatalysts with high activity in both acidic and alkaline media is of great significance for adapting to diverse electrolytic environments.In this study,MoSe_(2) and Ni...Developing hydrogen evolution reaction(HER)electrocatalysts with high activity in both acidic and alkaline media is of great significance for adapting to diverse electrolytic environments.In this study,MoSe_(2) and Ni_(3)Se_(4) nanosheets were successfully composited on high-entropy M_(4)C_(3)Tx MXene(M=Ti,V,Mo,Nb,Ta)via a hydrothermal method,constructing a novel heterostructured catalyst.This design leverages the excellent conductivity and multielement synergistic effect of high-entropy MXenes,which not only facilitates electron transport but also provides a robust platform for the uniform distribution of MoSe_(2) and Ni_(3)Se_(4) nanosheets,thereby exposing abundant active sites.Electrochemical tests indicate that the catalyst exhibits excellent HER performance in both 0.5 M H2SO4 and 1.0 M KOH electrolytes.Specifically,under acidic conditions,MoSe_(2)/Ni_(3)Se_(4)/M_(4)C_(3)Tx shows an overpotential of only 67 mV at a current density of 10 mA·cm^(-2) with a Tafel slope of 68.7 mV·dec^(-1),while under alkaline conditions,the overpotential at 10 mA·cm^(-2) is 73 mV with a Tafel slope of 77.8 mV·dec^(-1).Moreover,the catalyst demonstrates excellent long-term stability in both acidic and alkaline media.This work provides a new strategy for designing efficient and stable HER catalysts suitable for harsh acid-base environments.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52062002 and 51961006)the Open Foundation of Guangxi Key Laboratory of Processing for Nonferrous Metals and Featured Materials,Guangxi University,China(2021GXYSOF01).
文摘A series of single-phase double perovskite Pr1-xGdxBaCo_(2)-yFeyO_(5+σ)(x=0,0.5 and 1,0≤y≤1)materials were engineered through A/B site co-doping strategy to improve the mechanical,electrical and electrochemical properties as potential cathode materials for the application of intermediate solid oxide fuel cells(IT-SOFCs).The corresponding thermochemical stability,thermal expansion behavior,electrical conductivity and cathodic polarization resistance of the materials were systematically investigated.It was found that the A-site dual lanthanide doped Pr_(0.5)Gd_(0.5)BaCo_(2)O_(5+σ)(PGBCO)exhibits improved electrical conductivity,reduced thermal expansion,and comparatively low electrochemical polarization resistance versus single lanthanide double perovskite,PrBaCo_(2)O_(5+σ)(PBCO)and GdBaCo_(2)O_(5+σ)(GBCO)materials.Further investigation on the effect of B-site Fe-doping on Pr_(0.5)Gd_(0.5)BaCo_(2)-yFeyO_(5)+σ(PGBCF-y,0≤y≤1)reveals that all the PGBCF-y compositions exhibit excellent chemical stability with Gd-doped ceria(GDC)at operating temperatures not higher than 1100℃.Besides,doping of Fe in B-site can effectively reduce the thermal expansion coefficients(TECs)of the Pr_(0.5)Gd_(0.5)BaCo_(2)O_(5)+σceramics at 30e1000℃.And the electrochemical impedance spectra(EIS)results show that the PGBCF-y|GDC|PGBCF-y symmetric cells have acceptable low area specific polarization resistances.Further examination of the cathodic polarization and characteristic capacitance from the AC impedance spectra by employing the relaxation time distribution(DRT)method demonstrated that charge transfer is the dominating subprocess for the oxygen transport through the materials.
基金supported by the Natural Science Foundation of Hubei Province(No.2025AFD061)the National Natural Science Foundation of China(Nos.52372067,52402074,92163208,and 52494933).
文摘Developing hydrogen evolution reaction(HER)electrocatalysts with high activity in both acidic and alkaline media is of great significance for adapting to diverse electrolytic environments.In this study,MoSe_(2) and Ni_(3)Se_(4) nanosheets were successfully composited on high-entropy M_(4)C_(3)Tx MXene(M=Ti,V,Mo,Nb,Ta)via a hydrothermal method,constructing a novel heterostructured catalyst.This design leverages the excellent conductivity and multielement synergistic effect of high-entropy MXenes,which not only facilitates electron transport but also provides a robust platform for the uniform distribution of MoSe_(2) and Ni_(3)Se_(4) nanosheets,thereby exposing abundant active sites.Electrochemical tests indicate that the catalyst exhibits excellent HER performance in both 0.5 M H2SO4 and 1.0 M KOH electrolytes.Specifically,under acidic conditions,MoSe_(2)/Ni_(3)Se_(4)/M_(4)C_(3)Tx shows an overpotential of only 67 mV at a current density of 10 mA·cm^(-2) with a Tafel slope of 68.7 mV·dec^(-1),while under alkaline conditions,the overpotential at 10 mA·cm^(-2) is 73 mV with a Tafel slope of 77.8 mV·dec^(-1).Moreover,the catalyst demonstrates excellent long-term stability in both acidic and alkaline media.This work provides a new strategy for designing efficient and stable HER catalysts suitable for harsh acid-base environments.
