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采用量子化学的密度泛函理论,研究二氧化碳在Fe(111)表面的可能吸附态(M1～M5),计算出稳定的吸附构型和吸附能。结果表明,当CO_2的O与表面形成强O-Fe双吸附键(M2,M5)时,吸附能最大,为强化学吸附;形成较弱双吸附键C-Fe及配位键O-Fe(M3)时,吸附能次之;当CO_2垂直底物表面吸附(M4)时,氧原子只能与Fe原子形成单键,吸附力很弱,为弱物理吸附;在M1吸附模式中,CO_2分子的C原子吸附在Fe原子上,M1的吸附能也不太大,约为1.87 ev,属于弱化学吸附。Mulliken电荷计算表明,当吸附分子CO_2电荷愈负,与底物的吸附力愈强,与吸附能的计算结果相一致,同时由于电子转移形成CO_2~x-,导致金属失去电子而易被腐蚀。
Quantum chemical density functional theory was used to study the possible adsorption states (M1 ~ M5) of carbon dioxide on Fe (111) surface, and the stable adsorption configuration and adsorption energy were calculated. The results showed that the adsorption energy was the largest for O-Fe double bond (O 2, M 5) on the surface of CO 2, which was a strong chemisorption. The formation of weak double bond C-Fe and O-Fe M3), followed by adsorption. When adsorbed on the surface of CO_2 vertical substrate (M4), the oxygen atom can only form a single bond with the Fe atom, and the adsorption force is weak and weakly physical adsorption. In the M1 adsorption mode, Of C atoms adsorbed on the Fe atom, M1 adsorption energy is not too large, about 1.87 ev, belonging to weak chemisorption. Mulliken charge calculation shows that when the charge of the adsorbed molecule CO 2 is more negative, the stronger the binding force with the substrate is, which is consistent with the calculated result of the adsorption energy. At the same time, due to the electron transfer to form CO 2 ~ x-, the metal loses electrons and is easily corroded.