A DFT study of methanol oxidation on Co3O4

• DFT calculations were performed to study methanol oxidation on Co3O4.
• On the (110)-B surface, CH3OH can form CO2, H2O and adsorbed H atom.
• On the (111)-B surface, CH3OH can just form CH2O and adsorbed H atom.
• Both Co3+ and O2f involved in (110)-B contribute to the high oxidation activity.

By means of spin polarized density functional theory with the GGA + U framework, the reaction mechanism of CH3OH oxidation on the Co3O4 (110)-B and (111)-B surfaces has been investigated. Adsorption situation and a part of reaction cycle for CH3OH oxidation are clarified. Our results indicated that: i) U value can affect the calculated energetic result significantly; ii) CH3OH can adsorb with surface lattice oxygen atom (O2f/O3f) to form CoO bond directly, and the adsorption of CH3OH and its decomposition products on (110)-B is more stable than on (111)-B, which means CH3OH prefers Co3 + better than Co2 +; iii) on the (110)-B surface, CH3OH can form CO2, H2O and adsorbed H atom. But on the (111)-B surface, CH3OH can just form formaldehyde (CH2O) and adsorbed H atom, this means oxidative capacity of (110)-B (Co3 +) is higher than (111)-B (Co2 +). The possible reasons corresponding to the high oxidative of (110)-B come from both Co3 + and O2f: Co3 + tends to bind adsorbed species for further decomposition and O2f tends to bind more hydrogenation atom involved in methanol due to its low-coordinates number compared to that of O3f.

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