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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Enhanced Oxidation Reactivity of WO3(001) Surface through the Formation of Oxygen Radical Centers
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Enhanced Oxidation Reactivity of WO3(001) Surface through the Formation of Oxygen Radical Centers

机译：通过形成氧自由基中心提高WO3（001）表面的氧化反应性

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The γ-WO3(001) surfaces doped by a series of group VB elements have been investigated by means of first-principles density functional theory (DFT) calculations combined with a slab model. Our results show that the doping of VB element is preferential under O-rich growth conditions and that the replacement of tungsten by Ta atom is energetically favorable among three group VB elements. The introduction of a group VB atom into the surface results in the downward shift of the Fermi level, and in most cases, the 2p states derived from the in-plane oxygen atom are still the dominate components at the Fermi level as before doping. However, the substitution of Ta dopant for 6-fold-coordinated tungsten atom (W_(6f)) at the top layer is a special case in which the 2p states of the top terminal oxygen atom just above Ta become the primary compositions at the Fermi level. Only in this model, the spin densities are mainly located on the terminal oxygen atoms near the Ta site, and the oxygen radical center observed in the gas-phase W3O_9~+ cluster is reproduced. Therefore, the formation of radical oxygen center in the condensed phase depends on not only the substituent site but also the type of the dopant. Moreover, additional calculations are performed to study the oxidation reaction of CO molecule on the above Ta doped surface, and results indicate that the energy barrier for CO oxidization is obviously reduced compared to the undoped one, which implies that the introduction of Ta at W_(6f) site can efficiently improve the oxidation reactivity of the WO3(001) surface.
机译：通过第一原理密度泛函理论（DFT）计算与平板模型相结合，研究了由一系列VB族元素掺杂的γ-WO3（001）表面。我们的结果表明，在富含O的生长条件下，VB元素的掺杂是优先的，在三组VB元素中，用Ta原子替代钨在能量上是有利的。将VB族原子引入表面导致费米能级向下移动，并且在大多数情况下，像掺杂之前一样，源自平面内氧原子的2p态仍然是费米能级的主要成分。但是，在顶层用Ta掺杂剂取代6倍配位的钨原子（W_（6f））是一种特殊情况，其中刚好在Ta上方的顶部末端氧原子的2p状态成为费米的主要成分水平。仅在该模型中，自旋密度主要位于Ta位点附近的末端氧原子上，并且再现了在气相W3O_9〜+簇中观察到的氧自由基中心。因此，在缩合相中自由基氧中心的形成不仅取决于取代基的位置，还取决于掺杂剂的类型。此外，还进行了额外的计算来研究上述Ta掺杂表面上CO分子的氧化反应，结果表明，与未掺杂Ta相比，CO氧化的能垒明显降低，这表明Ta在W_（ 6f）位点可以有效地改善WO3（001）表面的氧化反应性。

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