化学
甲醇
催化作用
氧气
空位缺陷
吸附
吸热过程
密度泛函理论
光化学
物理化学
速率决定步骤
分子
无机化学
结晶学
计算化学
有机化学
作者
Jingyun Ye,Changjun Liu,Donghai Mei,Qingfeng Ge
摘要
Methanol synthesis from CO2 hydrogenation on the defective In2O3(110) surface with surface oxygen vacancies has been investigated using periodic density functional theory calculations. The relative stabilities of six possible surface oxygen vacancies numbered from Ov1 to Ov6 on the perfect In2O3(110) surface were examined. The calculated oxygen vacancy formation energies show that the D1 surface with the Ov1 defective site is the most thermodynamically favorable while the D4 surface with the Ov4 defective site is the least stable. Two different methanol synthesis routes from CO2 hydrogenation over both D1 and D4 surfaces were studied, and the D4 surface was found to be more favorable for CO2 activation and hydrogenation. On the D4 surface, one of the O atoms of the CO2 molecule fills in the Ov4 site upon adsorption. Hydrogenation of CO2 to HCOO on the D4 surface is both thermodynamically and kinetically favorable. Further hydrogenation of HCOO involves both forming the C–H bond and breaking the C–O bond, resulting in H2CO and hydroxyl. The HCOO hydrogenation is slightly endothermic with an activation barrier of 0.57 eV. A high barrier of 1.14 eV for the hydrogenation of H2CO to H3CO indicates that this step is the rate-limiting step in the methanol synthesis on the defective In2O3(110) surface.
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