Density functional theoretical study of the tungsten-doped In 2 O 3 catalyst for CO 2 hydrogenation to methanol.

Indium oxide is a promising catalyst for CO 2 hydrogenation to methanol and has been extensively investigated in recent years. However, the studies on doped In 2 O 3 for methanol synthesis are relatively few, and tungsten-doped In 2 O 3 has not been reported yet. Herein, the mechanism of the methanol synthesis from CO 2 hydrogenation on the defective W-doped In 2 O 3 model (W-In 2 O 3 _D) has been investigated via density functional theory (DFT) calculations. The oxygen vacancy on the In 2 O 3 catalyst is essential for the activation and conversion of CO 2 . The introduction of tungsten results in higher electron density and electron localization on the oxygen vacancy, thus facilitating the activation of CO 2 . The methanol synthesis on the W-In 2 O 3 _D model takes the formate route via the H 3 CO intermediate. Compared with the In 2 O 3 _D model, the cleavage of the C-O bond, the removal of H 2 O*, and the conversion of HCOO* are promoted by the addition of W. Based on the energetic span model, the turnover frequency (TOF) for the methanol synthesis from CO 2 hydrogenation on the W-In 2 O 3 _D model is predicted as 9.0 × 10 -3 s -1 , which is much higher than the TOF of 4.5 × 10 -6 s -1 on the In 2 O 3 _D model. Overall, the introduction of tungsten makes the CO 2 hydrogenation to methanol kinetically more favorable.