单原子Pt增强α-Mo_2C(0001)抗硫中毒特性机理的第一性原理研究
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摘要
采用基于密度泛函理论(DFT)第一性原理方法研究了α-Mo_2C(0001)表面和Pt/α-Mo_2C(0001)表面抗硫中毒特性及其机理.发现干净的Mo_2C(0001)表面对含硫物种(S、HS和H2S)吸附很强(吸附能分别为-6.46、-4.15和-1.54 e V),极易S中毒.Pt的引入可以减弱含硫物种在Mo_2C(0001)表面的吸附,当含硫物种在Pt/Mo_2C(0001)表面Pt原子周围吸附时吸附能较小,在Pt原子顶位吸附时吸附能最小,远离Pt原子吸附时吸附能增大.因此,Pt的引入对Pt周围催化活性位点避免硫原子中毒起到很好的保护作用,达到抗硫中毒效果.预期提高Pt原子覆盖度,可以进一步降低含硫物种与Mo_2C(0001)表面的相互作用,更好地抗硫中毒,为设计高活性、高抗硫中毒性的Mo_2C基催化剂提供理论依据.
The tolerance of sulfur poisoning on both clean α-Mo_2C( 0001) and Pt/α-Mo_2C( 0001) surfaces are investigated using density functional theory( DFT) calculations with the periodic slab model. It is found that the adsorption of S,HS and H2 S on the clean Mo_2C( 0001) surface is very strong( with the adsorption energies of-6. 46,-4. 15,and-1. 54 e V,respectively). The introduction of Pt decreases the adsorption energies of S,HS and H2 S on the Mo_2C( 0001) surface. When the sulfides are adsorbed on the Pt/Mo_2C( 0001) surface around the Pt atom,the adsorption energy of sulfide is decreased and the adsorption on the top position of Pt atom has the smallest adsorption energy. The adsorption energy increases when the sulfides are farther away from Pt. Hence,the introduction of Pt can play an important role in protecting the catalytically active sites around Pt from the sulfur poisoning. It can be anticipated that the effect of sulfur tolerance can be further enhanced by increasing the coverage of Pt on Mo_2C( 0001). The present study provides guidance for the design of highly active and sulfur tolerant catalysts based on Mo_2C.
The tolerance of sulfur poisoning on both clean α-Mo_2C( 0001) and Pt/α-Mo_2C( 0001) surfaces are investigated using density functional theory( DFT) calculations with the periodic slab model. It is found that the adsorption of S,HS and H2 S on the clean Mo_2C( 0001) surface is very strong( with the adsorption energies of-6. 46,-4. 15,and-1. 54 e V,respectively). The introduction of Pt decreases the adsorption energies of S,HS and H2 S on the Mo_2C( 0001) surface. When the sulfides are adsorbed on the Pt/Mo_2C( 0001) surface around the Pt atom,the adsorption energy of sulfide is decreased and the adsorption on the top position of Pt atom has the smallest adsorption energy. The adsorption energy increases when the sulfides are farther away from Pt. Hence,the introduction of Pt can play an important role in protecting the catalytically active sites around Pt from the sulfur poisoning. It can be anticipated that the effect of sulfur tolerance can be further enhanced by increasing the coverage of Pt on Mo_2C( 0001). The present study provides guidance for the design of highly active and sulfur tolerant catalysts based on Mo_2C.
引文
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[2]Weaver J H,Bradshaw A M,vander Veen J F,et al.Angle-resolved photoemission studies of Ti C(111)and Ti C(100)[J].Phys.Rev.B,1980,22:4921.
[3]Zhang X L,Lu Z S,Yang Z X.A comparison study of oxygen reduction on the supported Pt,Pd,Au monolayer on WC(0001)[J].J.Power Sources,2016,321:163.
[4]Levy R.B,Boudart M.Platinum-like behavior of tungsten carbide in surface catalysis[J].Science,1973,181:547
[5]Schlatter J C,Oyama S T,Metcalf J E,et al.Catalytic behavior of selected transition-metal carbides,nitrides,and borides in the hydrodenitrogenation of quinoline[J].Ind.Eng.Chem.Res,1988,27:1648.
[6]Ramanathan S,Oyama S T.New catalysts for hydroprocessing:transition metal carbides and nitrides[J].J.Phys.Chem.,1995,99:16365.
[7]Huang B B,Zhang X H.Effects of In and Cu additions on the electromigration resistance of Sn-based solder:First-principles calculations[J].J.At.Mol.Phys.,2015,32:168(in Chinese)[黄彬彬,张星辉.In和Cu掺杂对Sn基钎料抗电性能影响的第一性原理研究[J].原子与分子物理学报,2015,32:168]
[8]Xu Q R,Li S,Li Y.et al.First-principles study on the hydrogenation of the O2on Cr N4embedded graphene[J].J.At.Mol.Phys.,2016,33:779(in Chinese)[许庆冉,李硕,李燕,等.第一性原理研究O2在Cr N4掺杂石墨烯上的氢化[J].原子与分子物理学报,2016,33:779]
[9]Guo Y W,Liu W F,Ding Y P.Electronic and magnetic properties of C-doped Zn S nanowires[J].J.Sichuan Univ.:Nat.Sci.Ed.,2016,53:1329(in Chinese)[郭玉玮,刘文芳,丁永萍.C掺杂Zn S纳米线电子性质和磁性质[J].四川大学学报:自然科学版,2016,53:1329]
[10]Yan Z X,Wang H G,Zhang M P,et al.Pt supported on Mo2C particles with synergistic effect and strong interaction force for methanol electro-oxidation[J].Electrochimica Acta,2013,95:218.
[11]Claridge J B,York A P E,Brungs A J,et al.New catalysts for the conversion of methane to synthesis gas:molybdenun,and tungsten carbides[J].J.Catal.,1998,180:85.
[12]Xu X P,Zhang Y X,Yang Z X,et al.Resistance to sulfur poisoning of Ni-based alloy with coinage(IB)metals[J].Appl.Surf.Sci.,2015,357:1785.
[13]Zhang X L,Yin Y,Li S S,et al.First-principles studies on the adsorption of S on the Pt skin Pt3Ni(111)surface[J].J.At.Mol.Phys.,2014,31:635(in Chinese)[张喜林,殷岩,李沙沙,等.S在Pt皮肤Pt3Ni(111)面吸附的第一性原理研究[J].原子与分子物理学报:2014,31:635]
[14]Lu Z S,Li S,Ma D W,et al.The mechanism of oxygen activation on single Pt-atom doped Sn O2(110)surface[J].J.Mater.Sci.,2016,51:10400.
[15]Xiao T C,Wang H T,York P K,et al.Effect of sulfur on the performance of molybdenum carbide catalysts for the partial oxidation of methane to synthesis gas[J].Catal.Lett.,2002,83:241.
[16]Schaidle J A,Lausche A C,Thompson L T.Effects of sulfur on Mo2C and Pt/Mo2C catalysts:Water gas shift reaction[J].J.Catal.,2010,272:235.
[17]Jiang R B,Guo W Y,Li M.et al.Density functional study of the reaction of SO2on Ir(111)[J].J.Phys.Chem.C,2009,113:18223.
[18]Perdew J P,Burke K,Wang Y.Generalized gradient approximation for the exchange-correlation hole of a many-electron system[J].Phys.Rev.B,1996,54:16533.
[19]Lu Z S,Ling Y L,lv P,et al.First principles study of gas molecules on Co-BN surface[J].J.At.Mol.Phys.,2017,34:522(in Chinese)[路战胜,梁艳丽,吕鹏,等.气体分子在Co-BN表面吸附的第一性原理研究[J].原子与分子物理学报,2017,34:522]
[20]Xue J,Wang H H,Wang Y Z,et al.First-principles study on the catalysis reactivity tuning of the fullerene from Fe N4embedded[J].J.At.Mol.Phys.,2016,33:1031(in Chinese)[薛洁,王欢欢,王裔喆,等.Fe N4掺杂对富勒烯催化特性调制的第一性原理研究[J].原子与分子物理学报,2016,33:1031]
[21]Xue J,Wang H H,Wang Y Z,et al.Density functional theory investigations of O2hydrogenation on Fe N4doped carbon nanotubes[J].J.At.Mol.Phys.,2017,34:250(in Chinese)[薛洁,王欢欢,王裔喆,等.O2在Fe N4掺杂碳纳米管上氢化特性的密度泛函理论研究[J].原子与分子物理学报,2017,34:250]
[22]Otani S,Ishizawa Y.Preparation of Mo2C single crystals by the floating zone method[J].J.Cryst.Growth.,1995,154:202.
[23]Wang T,Li W Y,Wang J G,et al.High coverage CO adsorption and dissociation on the orthorhombic Mo2C(100)surface[J].J.Phys.Chem.C,2014,118:3162.
[24]Han J W,Li L W,Sholl D S.Density functional theory study of H and CO adsorption on alkali-promoted Mo2C surfaces[J].J.Phys.Chem.C,2011,115:6870.
[25]Oyama S T,Yu C C,Ramanathan S.Transition metal bimetallic oxycarbides:synthesis,characterization,and activity studies[J].J.Catal.,1999,184:535.
[26]Lucy T E,Clair T P S,Oyama S T.Synthesis,characterization,and reactivity of tungsten oxynitride[J].J.Mater.Res.,1998,13:2321.
[27]Alfonso D R,Cugini A V,Sorescu D C.Adsorption and decomposition of H2S on Pd(1 1 1)surface:a first-principles study[J].Catal.Today,2005,99:315.
[28]Shen K,Zhang Y X,Wang J L,et al.A fiest principles study on the mechanism of sulfur poisoning for Pt-based electrode materials[J].J.At.Mol.Phys.,2011,28:156(in Chinese)[沈凯,张岩星,王金龙,等.Pt基电极材料硫中毒机理的计算机模拟研[J].原子与分子物理学报,2011,28:156]
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