Chang Ming-Wen, Sheu Wen-Shyan
Department of Chemistry, Fu-Jen Catholic University, Xinzhuang, New Taipei City 24205, Taiwan, Republic of China.
Phys Chem Chem Phys. 2017 Jan 18;19(3):2201-2206. doi: 10.1039/c6cp07185f.
Density functional theory is employed to investigate the role of Au charge in the water-gas-shift (WGS) reaction on a CeO(111) surface with a cerium atom replaced by a gold atom. The oxidation state of the gold atom, varied between +3 and -1, is controlled by altering the number and configuration of oxygen vacancies. The findings indicate that Au and Au are not catalytically active for the WGS reaction because of a high energy barrier of +1.54 eV required to dissociate water and +1.40 eV to produce H and CO, respectively. However, when Au is in a modest oxidation state of +1, the overall reaction barrier for the WGS reaction via the carboxyl mechanism is reduced to 0.79-0.98 eV. It therefore appears that Au species with an oxidation state of +1 play a significant role in the WGS reaction at low temperatures (T < ∼550 K).
采用密度泛函理论研究了在CeO(111)表面上一个铈原子被一个金原子取代的情况下，金电荷在水煤气变换（WGS）反应中的作用。通过改变氧空位的数量和构型来控制金原子的氧化态，其在+3到-1之间变化。研究结果表明，由于分别使水离解需要+1.54 eV的高能量势垒以及生成H和CO需要+1.40 eV的高能量势垒，Au⁰和Au³⁺对WGS反应没有催化活性。然而，当Au处于适度的+1氧化态时，通过羧基机制的WGS反应的总反应势垒降低到0.79 - 0.98 eV。因此，氧化态为+1的金物种在低温（T < ∼550 K）的WGS反应中似乎起着重要作用。
