Study of the relationship between the local geometric structure and the stability of La_(0.6)Sr_(0.4)MnO_(3-δ) and La_(0.6)Sr_(0.4)FeO_(3-δ)electrodes
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摘要
Sr-substituted ABO_3 perovskite oxides such as La_(0.6) Sr_(0.4 )Mn_(O3-δ)(LSM) and La_(0.6) Sr_(0.4) FeO_(3-δ)(LSF) are widely used as oxygen electrode materials in solid oxide cells. The substituted Sr is not adequately stable under the operating conditions, because of the surface segregation of Sr. Herein, we focused on investigating the relationship between the local geometric structure due to Sr substitution and stability of LSM and LSF. We characterized the local geometric structure of Sr atoms via X-ray absorption spectroscopy. A greater Debye-Waller factor and a longer bond length of both the second and third Sr-O shells were observed in LSF, which demonstrates that LSF has a higher local structural disorder and that Sr in LSF requires less energy to segregate. After 20 h of heat treatment in the presence of a Fe-Cr alloy interconnect, the Sr/La molar ratio on LSF was observed to be much larger than that on LSM. This result unequivocally suggests that Sr in LSF is not as stable as in LSM, and the reaction between Sr and Cr accelerates the Sr surface segregation in LSF.
Sr-substituted AB0_3 perovskite oxides such as La_(0.6) Sr_(0.4) MnO_(3-δ)(LSM) and La_(0.6 )Sr_(0.4 )FeO_(3-δ)(LSF) are widely used as oxygen electrode materials in solid oxide cells. The substituted Sr is not adequately stable under the operating conditions, because of the surface segregation of Sr. Herein, we focused on investigating the relationship between the local geometric structure due to Sr substitution and stability of LSM and LSF. We characterized the local geometric structure of Sr atoms via X-ray absorption spectroscopy. A greater Debye-Waller factor and a longer bond length of both the second and third Sr-O shells were observed in LSF, which demonstrates that LSF has a higher local structural disorder and that Sr in LSF requires less energy to segregate. After 20 h of heat treatment in the presence of a Fe-Cr alloy interconnect, the Sr/La molar ratio on LSF was observed to be much larger than that on LSM. This result unequivocally suggests that Sr in LSF is not as stable as in LSM, and the reaction between Sr and Cr accelerates the Sr surface segregation in LSF.
Sr-substituted AB0_3 perovskite oxides such as La_(0.6) Sr_(0.4) MnO_(3-δ)(LSM) and La_(0.6 )Sr_(0.4 )FeO_(3-δ)(LSF) are widely used as oxygen electrode materials in solid oxide cells. The substituted Sr is not adequately stable under the operating conditions, because of the surface segregation of Sr. Herein, we focused on investigating the relationship between the local geometric structure due to Sr substitution and stability of LSM and LSF. We characterized the local geometric structure of Sr atoms via X-ray absorption spectroscopy. A greater Debye-Waller factor and a longer bond length of both the second and third Sr-O shells were observed in LSF, which demonstrates that LSF has a higher local structural disorder and that Sr in LSF requires less energy to segregate. After 20 h of heat treatment in the presence of a Fe-Cr alloy interconnect, the Sr/La molar ratio on LSF was observed to be much larger than that on LSM. This result unequivocally suggests that Sr in LSF is not as stable as in LSM, and the reaction between Sr and Cr accelerates the Sr surface segregation in LSF.
引文
1.S.B.Adler,Factors governing oxygen reduction in solid oxide fuel cell cathodes.Chem.Rev.104,4791-4843(2004).https://doi.org/10.1021/cr020724o
2.D.J.L.Brett,A.Atkinson,N.P.Brandon et al.,Intermediate temperature solid oxide fuel cells.Chem.Soc.Rev.37,1568-1578(2008).https://doi.org/10.1039/B612060C
3.E.V.Tsipis,V.V.Kharton,Electrode materials and reaction mechanisms in solid oxide fuel cells:a brief review.J.Solid State Electron.15,1007-1040(2011).https://doi.org/10.1007/s10008-011-1341-8
4.H.Ullmann,N.Trofimenko,F.Tietz et al.,Correlation between thermal expansion and oxide ion transport in mixed conducting perovskite-type oxides for SOFC cathodes.Solid State Ionics138,79-90(2000).https://doi.org/10.1016/S0167-2738(00)00770-0
5.C.Xia,W.Rauch,F.Chen et al.,Sm0.5Sr0.5CoO3cathodes for low-temperature SOFCs.Solid State Ionics 149,11-19(2002).https://doi.org/10.1016/S0167-2738(02)00131-5
6.Z.Shao,S.M.Haile,A high-performance cathode for the next generation of solid-oxide fuel cells.Nature 431,170-173(2004).https://doi.org/10.1038/nature02863
7.W.G.Wang,M.Mogensen,High-performance lanthanum-ferritebased cathode for SOFC.Solid State Ionics 176,457-462(2005).https://doi.org/10.1016/j.ssi.2004.09.007
8.P.Hjalmarsson,M.S?gaard,M.Mogensen,Electrochemical performance and degradation of(La0.6Sr0.4)0.99CoO3-das porous SOFC-cathode.Solid State Ionics 179,1422-1426(2008).https://doi.org/10.1016/j.ssi.2007.11.010
9.S.P.Jiang,Development of lanthanum strontium manganite perovskite cathode materials of solid oxide fuel cells:a review.J.Mater.Sci.43,6799-6833(2008).https://doi.org/10.1007/s10853-008-2966-6
10.H.Ji,J.Hwang,K.J.Yoon et al.,Enhanced oxygen diffusion in epitaxial lanthanum-strontium-cobaltite thin film cathodes for micro solid oxide fuel cells.Energy Environ.Sci.6,116-120(2013).https://doi.org/10.1039/C2EE21647G
11.K.Hosoi,H.Hagiwara,S.Ida et al.,La0.8Sr0.2FeO3-das fuel electrode for solid oxide reversible cells using LaGaO3-based oxide electrolyte.J.Phys.Chem.C 120,16110-16117(2016).https://doi.org/10.1021/acs.jpcc.5b12755
12.S.P.Jiang,Issues on development of(La,Sr)MnO3cathode for solid oxide fuel cells.J.Power Sources 124,390-402(2003).https://doi.org/10.1016/S0378-7753(03)00814-0
13.W.A.Harrison,Origin of Sr segregation at La1-xSrxMnO3surfaces.Phys.Rev.B 83,155437(2011).https://doi.org/10.1103/PhysRevB.83.155437
14.H.Ding,A.V.Virkar,M.Liu et al.,Suppression of Sr surface segregation in La1-xSrxCo1-yFeyO3:a first principles study.Phys.Chem.Chem.Phys.15,489-496(2013).https://doi.org/10.1039/C2CP43148C
15.F.Wang,M.Nishi,M.E.Brito et al.,Sr and Zr diffusion in LSCF/10GDC/8YSZ triplets for solid oxide fuel cells(SOFCs).J.Power Sources 258,281-289(2014).https://doi.org/10.1016/j.jpowsour.2014.02.046
16.N.Tsvetkov,Q.Lu,L.Sun et al.,Improved chemical and electrochemical stability of perovskite oxides with less reducible cations at the surface.Nat.Mater.15,1010-1016(2016).https://doi.org/10.1038/nmat4659
17.Y.Li,W.Zhang,Y.Zheng et al.,Controlling cation segregation in perovskite-based electrodes for high electro-catalytic activity and durability.Chem.Soc.Rev.46,6345-6378(2017).https://doi.org/10.1039/C7CS00120G
18.J.A.Kilner,M.Burriel,Materials for intermediate-temperature solid-oxide fuel cells.Annu.Rev.Mater.Res.44,365-393(2014).https://doi.org/10.1146/annurev-matsci-070813-113426
19.N.Ortiz-Vitoriano,I.R.Larramendi,S.N.Cook et al.,The formation of performance enhancing pseudo-composites in the highly active La1-xCaxFe0.8Ni0.2O3system for IT-SOFC application.Adv.Funct.Mater.23,5131-5139(2013).https://doi.org/10.1002/adfm.201300481
20.J.Druce,H.Te′llez,M.Burriel et al.,Surface termination and subsurface restructuring of perovskite-based solid oxide electrode materials.Energy Environ.Sci.7,3593-3599(2014).https://doi.org/10.1039/C4EE01497A
21.N.Caillol,M.Pijolat,E.Siebert,Investigation of chemisorbed oxygen,surface segregation and effect of post-treatments on La0.8Sr0.2MnO3powder and screen-printed layers for solid oxide fuel cell cathodes.Appl.Surf.Sci.253,4641-4648(2007).https://doi.org/10.1016/j.apsusc.2006.10.019
22.T.T.Fister,D.D.Fong,J.A.Eastman et al.,In situ characterization of strontium surface segregation in epitaxial La0.7Sr0.3Mn O3thin films as a function of oxygen partial pressure.Appl.Phys.Lett.93,151904(2008).https://doi.org/10.1063/1.2987731
23.A.K.Huber,M.Falk,M.Rohnke et al.,In situ study of activation and de-activation of LSM fuel cell cathodes-electrochemistry and surface analysis of thin-film electrodes.J.Catal.294,79-88(2012).https://doi.org/10.1016/j.jcat.2012.07.010
24.B.Hu,M.Keane,M.K.Mahapatra et al.,Stability of strontiumdoped lanthanum manganite cathode in humidified air.J.Power Sources 248,196-204(2014).https://doi.org/10.1016/j.jpowsour.2013.08.098
25.X.Chen,Y.Zhen,J.Li et al.,Chromium deposition and poisoning in dry and humidified air at(La0.8Sr0.2)0.9MnO3?dcathodes of solid oxide fuel cells.Int.J.Hydrogen Energy 35,2477-2485(2010).https://doi.org/10.1016/j.ijhydene.2009.12.185
26.S.P.Jiang,X.Chen,Chromium deposition and poisoning of cathodes of solid oxide fuel cells-a review.Int.J.Hydrogen Energy 39,505-531(2014).https://doi.org/10.1016/j.ijhydene.2013.10.042
27.B.Wei,K.Chen,L.Zhao et al.,Chromium deposition and poisoning at La0.6Sr0.4Co0.2Fe0.8O3oxygen electrodes of solid oxide electrolysis cells.Phys.Chem.Chem.Phys.17,1601-1609(2015).https://doi.org/10.1039/c4cp05110f
28.D.Roehrens,A.Neumann,A.Beez et al.,Formation of chromium containing impurities in(La,Sr)MnO3solidoxidefuelcell cathodes under stack operating conditions and its effect on performance.Ceram.Int.42,9467-9474(2016).https://doi.org/10.1016/j.ceramint.2016.03.010
29.W.Lee,J.W.Han,Y.Chen et al.,Cation size mismatch and charge interactions drive dopant segregation at the surfaces of manganite perovskites.J.Am.Chem.Soc.13,7909-7925(2013).https://doi.org/10.1021/ja3125349
30.L.Nie,M.Liu,Y.Zhang et al.,La0.6Sr0.4Co0.2Fe0.8O3-dcathodes infiltrated with samarium-doped cerium oxide for solid oxide fuel cells.J.Power Sources 195,4704-4708(2010).https://doi.org/10.1016/j.jpowsour.2010.02.049
31.P.Y.Chou,C.J.Ciou,Y.C.Lee et al.,Effect of La0.1Sr0.9Co0.5-Mn0.5O3-dprotective coating layer on the performance of La0.6Sr0.4Co0.8Fe0.2O3-dsolid oxide fuel cell cathode.J.Power Sources 197,12-19(2012).https://doi.org/10.1016/j.jpowsour.2011.09.017
32.D.Ding,M.Liu,Z.Liu et al.,Efficient electro-catalysts for enhancing surface activity and stability of SOFC cathodes.Adv.Energy Mater.3,1149-1154(2013).https://doi.org/10.1002/aenm.201200984
33.X.Zhu,D.Ding,Y.Li et al.,Development of La0.6Sr0.4Co0.2-Fe0.8O3-dcathode with an improved stability via La0.8Sr0.2-MnO3-film impregnation.Int.J.Hydrogen Energy 38,5375-5382(2013).https://doi.org/10.1016/j.ijhydene.2013.02.091
34.K.Chen,N.Ai,K.M.O’Donnell et al.,Highly chromium contaminant tolerant BaO infiltrated La0.6Sr0.4Co0.2Fe0.8O3-dcathodes for solid oxide fuel cells.Phys.Chem.Chem.Phys.17,4870-4874(2015).https://doi.org/10.1039/c4cp04172k
35.O.Haas,U.F.Vogt,C.Soltmann et al.,The Fe K-edge X-ray absorption characteristics of La1-xSrxFeO3-dprepared by solid state reaction.Mater.Res.Bull.44,1397-1404(2009).https://doi.org/10.1016/j.materresbull.2008.11.026
36.O.Haas,C.Ludwig,U.Bergmann et al.,X-ray absorption investigation of the valence state and electronic structure of La1-xCaxCoO3-din comparison with La1-xSrxCoO3-dand La1-xSrxFeO3-d.J.Solid State Chem.184,3163-3171(2011).https://doi.org/10.1016/j.jssc.2011.09.027
37.M.Liu,M.E.Lynch,K.Blinn et al.,Rational SOFC material design:new advances and tools.Mater.Today 14,534-546(2011).https://doi.org/10.1016/S1369-7021(11)70279-6
38.M.Newville,IFEFFIT:interactive XAFS analysis and FEFFfitting.J.Synchrotron Radiat.8,322-324(2001).https://doi.org/10.1107/S0909049500016964
39.Y.Orikasa,T.Nakao,M.Oishi et al.,Local structural analysis for oxide ion transport in La0.6Sr0.4FeO3-dcathodes.J.Mater.Chem.21,14013-14019(2011).https://doi.org/10.1039/C1JM11358E
2.D.J.L.Brett,A.Atkinson,N.P.Brandon et al.,Intermediate temperature solid oxide fuel cells.Chem.Soc.Rev.37,1568-1578(2008).https://doi.org/10.1039/B612060C
3.E.V.Tsipis,V.V.Kharton,Electrode materials and reaction mechanisms in solid oxide fuel cells:a brief review.J.Solid State Electron.15,1007-1040(2011).https://doi.org/10.1007/s10008-011-1341-8
4.H.Ullmann,N.Trofimenko,F.Tietz et al.,Correlation between thermal expansion and oxide ion transport in mixed conducting perovskite-type oxides for SOFC cathodes.Solid State Ionics138,79-90(2000).https://doi.org/10.1016/S0167-2738(00)00770-0
5.C.Xia,W.Rauch,F.Chen et al.,Sm0.5Sr0.5CoO3cathodes for low-temperature SOFCs.Solid State Ionics 149,11-19(2002).https://doi.org/10.1016/S0167-2738(02)00131-5
6.Z.Shao,S.M.Haile,A high-performance cathode for the next generation of solid-oxide fuel cells.Nature 431,170-173(2004).https://doi.org/10.1038/nature02863
7.W.G.Wang,M.Mogensen,High-performance lanthanum-ferritebased cathode for SOFC.Solid State Ionics 176,457-462(2005).https://doi.org/10.1016/j.ssi.2004.09.007
8.P.Hjalmarsson,M.S?gaard,M.Mogensen,Electrochemical performance and degradation of(La0.6Sr0.4)0.99CoO3-das porous SOFC-cathode.Solid State Ionics 179,1422-1426(2008).https://doi.org/10.1016/j.ssi.2007.11.010
9.S.P.Jiang,Development of lanthanum strontium manganite perovskite cathode materials of solid oxide fuel cells:a review.J.Mater.Sci.43,6799-6833(2008).https://doi.org/10.1007/s10853-008-2966-6
10.H.Ji,J.Hwang,K.J.Yoon et al.,Enhanced oxygen diffusion in epitaxial lanthanum-strontium-cobaltite thin film cathodes for micro solid oxide fuel cells.Energy Environ.Sci.6,116-120(2013).https://doi.org/10.1039/C2EE21647G
11.K.Hosoi,H.Hagiwara,S.Ida et al.,La0.8Sr0.2FeO3-das fuel electrode for solid oxide reversible cells using LaGaO3-based oxide electrolyte.J.Phys.Chem.C 120,16110-16117(2016).https://doi.org/10.1021/acs.jpcc.5b12755
12.S.P.Jiang,Issues on development of(La,Sr)MnO3cathode for solid oxide fuel cells.J.Power Sources 124,390-402(2003).https://doi.org/10.1016/S0378-7753(03)00814-0
13.W.A.Harrison,Origin of Sr segregation at La1-xSrxMnO3surfaces.Phys.Rev.B 83,155437(2011).https://doi.org/10.1103/PhysRevB.83.155437
14.H.Ding,A.V.Virkar,M.Liu et al.,Suppression of Sr surface segregation in La1-xSrxCo1-yFeyO3:a first principles study.Phys.Chem.Chem.Phys.15,489-496(2013).https://doi.org/10.1039/C2CP43148C
15.F.Wang,M.Nishi,M.E.Brito et al.,Sr and Zr diffusion in LSCF/10GDC/8YSZ triplets for solid oxide fuel cells(SOFCs).J.Power Sources 258,281-289(2014).https://doi.org/10.1016/j.jpowsour.2014.02.046
16.N.Tsvetkov,Q.Lu,L.Sun et al.,Improved chemical and electrochemical stability of perovskite oxides with less reducible cations at the surface.Nat.Mater.15,1010-1016(2016).https://doi.org/10.1038/nmat4659
17.Y.Li,W.Zhang,Y.Zheng et al.,Controlling cation segregation in perovskite-based electrodes for high electro-catalytic activity and durability.Chem.Soc.Rev.46,6345-6378(2017).https://doi.org/10.1039/C7CS00120G
18.J.A.Kilner,M.Burriel,Materials for intermediate-temperature solid-oxide fuel cells.Annu.Rev.Mater.Res.44,365-393(2014).https://doi.org/10.1146/annurev-matsci-070813-113426
19.N.Ortiz-Vitoriano,I.R.Larramendi,S.N.Cook et al.,The formation of performance enhancing pseudo-composites in the highly active La1-xCaxFe0.8Ni0.2O3system for IT-SOFC application.Adv.Funct.Mater.23,5131-5139(2013).https://doi.org/10.1002/adfm.201300481
20.J.Druce,H.Te′llez,M.Burriel et al.,Surface termination and subsurface restructuring of perovskite-based solid oxide electrode materials.Energy Environ.Sci.7,3593-3599(2014).https://doi.org/10.1039/C4EE01497A
21.N.Caillol,M.Pijolat,E.Siebert,Investigation of chemisorbed oxygen,surface segregation and effect of post-treatments on La0.8Sr0.2MnO3powder and screen-printed layers for solid oxide fuel cell cathodes.Appl.Surf.Sci.253,4641-4648(2007).https://doi.org/10.1016/j.apsusc.2006.10.019
22.T.T.Fister,D.D.Fong,J.A.Eastman et al.,In situ characterization of strontium surface segregation in epitaxial La0.7Sr0.3Mn O3thin films as a function of oxygen partial pressure.Appl.Phys.Lett.93,151904(2008).https://doi.org/10.1063/1.2987731
23.A.K.Huber,M.Falk,M.Rohnke et al.,In situ study of activation and de-activation of LSM fuel cell cathodes-electrochemistry and surface analysis of thin-film electrodes.J.Catal.294,79-88(2012).https://doi.org/10.1016/j.jcat.2012.07.010
24.B.Hu,M.Keane,M.K.Mahapatra et al.,Stability of strontiumdoped lanthanum manganite cathode in humidified air.J.Power Sources 248,196-204(2014).https://doi.org/10.1016/j.jpowsour.2013.08.098
25.X.Chen,Y.Zhen,J.Li et al.,Chromium deposition and poisoning in dry and humidified air at(La0.8Sr0.2)0.9MnO3?dcathodes of solid oxide fuel cells.Int.J.Hydrogen Energy 35,2477-2485(2010).https://doi.org/10.1016/j.ijhydene.2009.12.185
26.S.P.Jiang,X.Chen,Chromium deposition and poisoning of cathodes of solid oxide fuel cells-a review.Int.J.Hydrogen Energy 39,505-531(2014).https://doi.org/10.1016/j.ijhydene.2013.10.042
27.B.Wei,K.Chen,L.Zhao et al.,Chromium deposition and poisoning at La0.6Sr0.4Co0.2Fe0.8O3oxygen electrodes of solid oxide electrolysis cells.Phys.Chem.Chem.Phys.17,1601-1609(2015).https://doi.org/10.1039/c4cp05110f
28.D.Roehrens,A.Neumann,A.Beez et al.,Formation of chromium containing impurities in(La,Sr)MnO3solidoxidefuelcell cathodes under stack operating conditions and its effect on performance.Ceram.Int.42,9467-9474(2016).https://doi.org/10.1016/j.ceramint.2016.03.010
29.W.Lee,J.W.Han,Y.Chen et al.,Cation size mismatch and charge interactions drive dopant segregation at the surfaces of manganite perovskites.J.Am.Chem.Soc.13,7909-7925(2013).https://doi.org/10.1021/ja3125349
30.L.Nie,M.Liu,Y.Zhang et al.,La0.6Sr0.4Co0.2Fe0.8O3-dcathodes infiltrated with samarium-doped cerium oxide for solid oxide fuel cells.J.Power Sources 195,4704-4708(2010).https://doi.org/10.1016/j.jpowsour.2010.02.049
31.P.Y.Chou,C.J.Ciou,Y.C.Lee et al.,Effect of La0.1Sr0.9Co0.5-Mn0.5O3-dprotective coating layer on the performance of La0.6Sr0.4Co0.8Fe0.2O3-dsolid oxide fuel cell cathode.J.Power Sources 197,12-19(2012).https://doi.org/10.1016/j.jpowsour.2011.09.017
32.D.Ding,M.Liu,Z.Liu et al.,Efficient electro-catalysts for enhancing surface activity and stability of SOFC cathodes.Adv.Energy Mater.3,1149-1154(2013).https://doi.org/10.1002/aenm.201200984
33.X.Zhu,D.Ding,Y.Li et al.,Development of La0.6Sr0.4Co0.2-Fe0.8O3-dcathode with an improved stability via La0.8Sr0.2-MnO3-film impregnation.Int.J.Hydrogen Energy 38,5375-5382(2013).https://doi.org/10.1016/j.ijhydene.2013.02.091
34.K.Chen,N.Ai,K.M.O’Donnell et al.,Highly chromium contaminant tolerant BaO infiltrated La0.6Sr0.4Co0.2Fe0.8O3-dcathodes for solid oxide fuel cells.Phys.Chem.Chem.Phys.17,4870-4874(2015).https://doi.org/10.1039/c4cp04172k
35.O.Haas,U.F.Vogt,C.Soltmann et al.,The Fe K-edge X-ray absorption characteristics of La1-xSrxFeO3-dprepared by solid state reaction.Mater.Res.Bull.44,1397-1404(2009).https://doi.org/10.1016/j.materresbull.2008.11.026
36.O.Haas,C.Ludwig,U.Bergmann et al.,X-ray absorption investigation of the valence state and electronic structure of La1-xCaxCoO3-din comparison with La1-xSrxCoO3-dand La1-xSrxFeO3-d.J.Solid State Chem.184,3163-3171(2011).https://doi.org/10.1016/j.jssc.2011.09.027
37.M.Liu,M.E.Lynch,K.Blinn et al.,Rational SOFC material design:new advances and tools.Mater.Today 14,534-546(2011).https://doi.org/10.1016/S1369-7021(11)70279-6
38.M.Newville,IFEFFIT:interactive XAFS analysis and FEFFfitting.J.Synchrotron Radiat.8,322-324(2001).https://doi.org/10.1107/S0909049500016964
39.Y.Orikasa,T.Nakao,M.Oishi et al.,Local structural analysis for oxide ion transport in La0.6Sr0.4FeO3-dcathodes.J.Mater.Chem.21,14013-14019(2011).https://doi.org/10.1039/C1JM11358E