Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Phys Chem Chem Phys. 2011 Jan 21;13(3):978-84. doi: 10.1039/c0cp01138j. Epub 2010 Nov 9.
A complete catalytic cycle for carbon monoxide (CO) oxidation to carbon dioxide (CO(2)) by molecular oxygen on the Co(3)O(4)(110) surface was obtained by density functional theory plus the on-site Coulomb repulsion (DFT + U). Previously observed high activity of Co(3)O(4) to catalytically oxidize CO at very low temperatures is explained by a unique twofold-coordinate oxygen site on Co(3)O(4)(110). The CO molecule extracts this oxygen with a computed barrier of 27 kJ/mol. The extraction leads to CO(2) formation and an oxygen vacancy on Co(3)O(4)(110). Then, the O(2) molecule dissociates without a barrier between two neighboring oxygen vacancies (which are shown to have high surface mobility), thereby replenishing the twofold-coordinate oxygen sites on the surface and enabling the catalytic cycle. In contrast, extracting the threefold-coordinate oxygen site on Co(3)O(4)(110) has a higher barrier. Our work furnishes a molecular-level mechanism of Co(3)O(4)'s catalytic power, which may help understand previous experimental results and oxidation catalysis by transition metal oxides.
通过密度泛函理论加局域库仑排斥（DFT + U），在 Co(3)O(4)(110)表面上获得了一氧化碳（CO）氧化为二氧化碳（CO(2))的完整催化循环。先前观察到 Co(3)O(4)在非常低的温度下催化氧化 CO 的高活性，可通过 Co(3)O(4)(110)上独特的两倍配位氧位来解释。CO 分子以计算出的 27 kJ/mol 的势垒提取该氧。提取导致 CO(2)形成和 Co(3)O(4)(110)上的氧空位。然后，O(2)分子在两个相邻氧空位（具有高表面迁移率）之间无势垒解离，从而补充表面上的两倍配位氧位并使催化循环继续进行。相比之下，提取 Co(3)O(4)(110)上的三倍配位氧位具有更高的势垒。我们的工作提供了 Co(3)O(4)催化能力的分子水平机制，这可能有助于理解先前的实验结果和过渡金属氧化物的氧化催化作用。
