【摘要】 采用密度泛函理论与周期性平板模型相结合的方法,对HCOOH在Pd(111)表面top,fcc,hcp,bridge四个吸附位和Pd-Fe(111)表面Pd-top,Fe-top,PdPd-bridge,PdFe-bridge,FeFe-bridge,Pd2Fehcp,PdFe2-hcp,Pd2Fe-fcc,PdFe2-fcc等9个吸附位的13种吸附模型进行了能量计算、构型优化,得到了HCOOH较有利的吸附位;并对清洁表面进行能带分析.结果表明:掺杂Fe后,Pd催化剂对HCOOH催化活性增强;HCOOH在Pd(111)表面的最稳定吸附位fcc的吸附能是-41.8kJ·mol-1,在Pd-Fe(111)表面的最稳定吸附位Pd2Fe-hcp的吸附能是-126.5kJ·mol-1,而且HCOOH在金属表面属于化学吸附.更多还原

【Abstract】 The density functional theory(DFT)and periodic slab model are used to investigate Formic acid adsorption on Pd(111)and Pd-Fe(111)surfaces.The adsorption energies,equilibrium geometries of Formic acid on four possible sites(top,fcc,hcp,and bridge)on Pd(111)surface and on nine possible sites(Pd-top,Fe-top,PdPd-bridge,PdFe-bridge,FeFe-bridge,Pd2Fe-hcp,PdFe2-hcp,Pd2Fe-fcc,PdFe2-fcc)on Pd-Fe(111)surface are predicted and compared.The relatively favorable adsorption sites are found.Band structures of the clean Pd(111)and Pd-Fe(111)surfaces and density of states analysis of the most stable sites are discussed.The results reveal that the range of energy band for Iron-doped Pd(111)surface are enhanced and the activity of catalyst are improved;the adsorption energy for Formic acid adsorption on the most stable sites on Pd(111)and Pd-Fe(111)surfaces are-41.8and-126.5kJ ·mol-1,respectively.The calculated results show that there are chemical bonds between formic acid and Pd(111),Pd-Fe(111)surface,respectively.更多还原