铈和铂掺杂钙钛矿催化剂的第一性原理研究
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摘要
用醇盐法制备了铈和铂元素掺杂的钙钛矿催化材料。用扫描电子显微镜(SEM)、X射线衍射(XRD)和透射电子显微镜(TEM)对材料进行了表征。结果表明,催化材料颗粒均匀,直径约30 nm,以钙钛矿(Ca Ti O_3)和烧绿石(Ca_2Ti_2O_6)共存,铈和铂元素分散均匀并形成掺杂的固溶体结构。构建了Pt(111)和铂铈原子替代钛原子的钙钛矿掺杂模型,并采用基于密度泛函理论的第一性原理对CaTi_xPt_yCe_zO_3材料的形成能、态密度和吸附性能进行了对比研究。结果表明,CaTi_(0.9)Pt_(0.05)Ce_(0.05)O_3对NH_3的吸附能与Pt(111)最接近,掺杂使体系吸附能降低,有利于氨氧化催化的吸附和脱附。
Pt-and Ce-doped CaTiO_3 catalytic materials were prepared by the alkoxide method,and then they were characterized in detail by using SEM,XRD and TEM.The results showed that the particles of the catalytic materials were uniform with a diameter of about 30 nm and co-existed in the state of perovskite(CaTiO_3)and pyrochlore(Ca_2Ti_2O_6).Ce and Pt were dispersed evenly,forming a doped solid solution structure.A perovskite doping model was constructed in which titanium atom had been replaced by Pt(111),platinum and cerium atom.Furthermore,the formation energy,state density and adsorption energy of NH_3 on CaTi_xPt_yCe_zO_3 were calculated by means of the first principles based on the density functional theory.The results show that the adsorption energy of NH_3 on CaTi_(0.9)Pt_(0.05)Ce_(0.05)O_3 is the closest to that on Pt(111).Doped perovskite can lower the adsorption energy of the system,which will facilitate the adsorption and desorption of ammonia oxidation catalysis.
Pt-and Ce-doped CaTiO_3 catalytic materials were prepared by the alkoxide method,and then they were characterized in detail by using SEM,XRD and TEM.The results showed that the particles of the catalytic materials were uniform with a diameter of about 30 nm and co-existed in the state of perovskite(CaTiO_3)and pyrochlore(Ca_2Ti_2O_6).Ce and Pt were dispersed evenly,forming a doped solid solution structure.A perovskite doping model was constructed in which titanium atom had been replaced by Pt(111),platinum and cerium atom.Furthermore,the formation energy,state density and adsorption energy of NH_3 on CaTi_xPt_yCe_zO_3 were calculated by means of the first principles based on the density functional theory.The results show that the adsorption energy of NH_3 on CaTi_(0.9)Pt_(0.05)Ce_(0.05)O_3 is the closest to that on Pt(111).Doped perovskite can lower the adsorption energy of the system,which will facilitate the adsorption and desorption of ammonia oxidation catalysis.
引文
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[2]韩非,刘欣.两种钯合金网在硝酸催化网中捕集铂的比较[J].贵金属,2017,38(1):31-35.HAN F,LIU X.Comparison of Pt catchment between two Pd alloy in nitric acid catalyst gauze[J].Precious metals,2017,38(1):31-35.
[3]SADYKOV V A,ISUPOVA L A,ZOLOTARSKII I A,et al.Oxide catalysts for ammonia oxidation in nitric acid production:Properties and perspectives[J].Applied catalysis A:General,2000,204(1):59-87.
[4]TANIGUCHI M,TANAKA H,UENISHI M,et al.The self-regenerative Pd-,Rh-,and Pt-perovskite catalysts[J].Topics in catalysis,2007,42(1/4):367-371.
[5]GAI Y,LI J,LI S S,et al.Design of narrow-gap TiO2:Apassivated codoping approach for enhanced photoelectrochemical activity[J].Physical review letters,2009,102(3):036402.
[6]CHOI M,OBA F,TANAKA I.First-principles study of native defects and lanthanum impurities in NaTaO3[J].Physical review B,2008,78:014115.
[7]VANDERBILT D.Soft self-consistent pseudopotentials in a generalized eigenvalue formalism[J].Physical review B,1990,41(11):7892-7895.
[8]BL?CHL P E.Generalized separable potentials for electronic-structure calculations[J].Physical review B,1990,41(8):5414-5416.
[9]LIU G,LIU S B,XU B,et al.Generalized gradient approximation made simple[J].Journal of applied physics,2015,112(12):666.
[10]LV Z Q,DONG F,ZHOU Z A,et al.Structural properties,phase stability and theoretical hardness of Cr23-xMxC6(M=Mo,W;x=0-3)[J].Journal of alloys and compounds,2014,607:207-214.
[11]ZHANG C S,YAN M F,YOU Y,et al.Stability and properties of alloyedε-(Fe1-xMx)3N nitrides(M=Cr,Ni,Mo,V,Co,Nb,Mn,Ti and Cu):A first-principles calculations[J].Journal of alloys and compounds,2014,615:854-862.
[12]BLO?SKI P,KIEJNA A,HAFNER J.Theoretical study of oxygen adsorption at the Fe(110)and(100)surfaces[J].Surface science,2005,590(1):88-100.
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