CAJ | 학술논문

采用密度泛函理论(DFT)和周期平板模型,研究两种WC(0001)表面的几何结构和表而能,并对Pt原子单层(Pt_ML)在两种WC(0001)表而的高对称性吸附位上的吸附能和分离功进行计算.结果发现,终止于W原子的WC(0001)为最稳定的WC(0001)表面,Pt原子单层以hcp位的方式吸附于W终止的WC(0001)表面是Pt_(ML)/WC(0001)体系最稳定的几何构型.在此基础上研究了CO分子和H原子分别在Pt_(ML)/WC(0001)表面和具有相似表面结构的Pt(111)表面的吸附行为.在0.25 ML(monolayer)低覆盖度下,与在Pt(111)表面相比,在Pt_(ML)/WC(0001)表面卜的Pt-C间距明显拉长和CO分子吸附能减少,说明Pt_(ML)/WC(0001)表面抗CO中毒能力比Pt(111)表面高;态密度分析进一步解释了CO分子与不同表面Pt原子的成键机理.在同一覆盖度下,H原子在Pt_(ML)/WC(0001)表面的最大吸附能等于甚至略高于在Pt(111)表面的,表明Pt/WC对氢气氧化反应具有良好的催化活性,是一种很有前途的质子交换膜燃料电池(PEMFC)阳极催化剂.
채용밀도범함이론(DFT)화주기평판모형,연구량충WC(0001)표면적궤하결구화표이능,병대Pt원자단층(Pt_ML)재량충WC(0001)표이적고대칭성흡부위상적흡부능화분리공진행계산.결과발현,종지우W원자적WC(0001)위최은정적WC(0001)표면,Pt원자단층이hcp위적방식흡부우W종지적WC(0001)표면시Pt_(ML)/WC(0001)체계최은정적궤하구형.재차기출상연구료CO분자화H원자분별재Pt_(ML)/WC(0001)표면화구유상사표면결구적Pt(111)표면적흡부행위.재0.25 ML(monolayer)저복개도하,여재Pt(111)표면상비,재Pt_(ML)/WC(0001)표면복적Pt-C간거명현랍장화CO분자흡부능감소,설명Pt_(ML)/WC(0001)표면항CO중독능력비Pt(111)표면고;태밀도분석진일보해석료CO분자여불동표면Pt원자적성건궤리.재동일복개도하,H원자재Pt_(ML)/WC(0001)표면적최대흡부능등우심지략고우재Pt(111)표면적,표명Pt/WC대경기양화반응구유량호적최화활성,시일충흔유전도적질자교환막연료전지(PEMFC)양겁최화제.
Density functional theory (DFT) calculations and periodic slab models were used to investigate the geometrical structures and surface energies of two different WC(0001)surfaces.The adhesion energies and separation work of Pt monolayer adhesion on the two WC(0001) surfaces at high-symmetry sites were calculated.Resuts show that the W-terminated WC(0001)is favored and that the W-terminated surface with Pt monolayer adhesion at the hcp site is the most stable Pt_(ML)/WC(0001)structure.On the basis of the above results,the adsorption behavior of the CO molecule and hydrogen atom on the Pt_(ML)/WC(0001)surface was compared with those obtained on the Pt(111)surface with a surface structure similar to the Pt_(ML)/WC(0001)surface.At a low coverage of 0.25 ML(monolayer),an obvious elongation of the Pt-C distance and a decrease in CO adsorption energy show that the Pt_(ML)/WC(0001)surface,relative to the Pt(111)surface,exhibits much improved resistance to CO poisoning.The density of states further explains the bonding mechanism of CO and Pt atoms on different surfaces.At the Same coverage,the maximum hydrogen adsorption energy on the Pt_(ML)/WC(0001)surface is equal to or even slightly higher than that on the Pt(111)surface.This suggests that Pt/WC possesses good catalytic activity during the hydrogen oxidation reaction and is a promising alternative anode catalyst for proton exchange membrane fuel cells (PEMFC).