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本文用UPS,XPS研究了贮氢材料MlNi_5(Ml=La,Ce,Pr,Nd)的CO,O_2和H_2O的中毒,在UPS谱中,我们观察到在E_F以下峰α(0.3eV)和峰b(1.2eV)强度随中毒气体暴露量增加有显著变化,并向低动能端位移,逐渐形成肩峰,与此同时,峰c(6eV)和峰d(9.5eV)的强度随暴露量增加而增加,并有能量位移,配合XPS分析,分别确定相应的化学态。氧中毒后的MlNi_5,经300℃加氢还原,从UPS谱可以看到峰α,b强度增加;H_2O和CO中毒后,在超高真空条件下,分别经300℃加热处理,和Ar~+剥离方法,均获得类似的效果,XPS分析进一步证实了这些结果。 实验给出了贮氢材料MlNi_5中过渡金属镍的d电子与气体自由分子轨道间电荷转移的信息,为在实际应用中认识此类贮氢合金的表面催化中毒和再生提供了依据。
In this paper, UPS and XPS were used to study the poisoning of CO, O_2 and H_2O in hydrogen storage material MlNi_5 (Ml = La, Ce, Pr, Nd) The intensity of b (1.2eV) changed significantly with the increase of toxic gas exposure and shifted to the low kinetic energy, which gradually formed a shoulder. At the same time, the intensities of peak c (6eV) and peak d (9.5eV) increased with the increase of exposure And increase, and energy displacement, with the XPS analysis, respectively, to determine the corresponding chemical state. After oxygen poisoning, MlNi_5 was hydrogenated and reduced at 300 ℃. From the spectrum of UPS, it can be seen that the intensity of peak α and b increased. After H_2O and CO poisoning, under high vacuum, Stripping method, have similar results, XPS analysis further confirmed these results. The experiment gives the information about the charge transfer between the d electrons and the gas free molecular orbitals of the transition metal nickel in the hydrogen storage material MlNi_5, which provides a basis for understanding the surface catalysis and regeneration of such hydrogen storage alloys in practical applications.