CO2 Activation and Reaction on Zn-Deposited Cu Surfaces Studied by Ambient-Pressure X-ray Photoelectron Spectroscopy
CO2 Activation and Reaction on Zn-Deposited Cu Surfaces Studied by Ambient-Pressure X-ray Photoelectron Spectroscopy
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DOI：
10.1021/acscatal.9b00041
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发表时间：
2019-05-01
期刊：
影响因子：
12.9
通讯作者：
Yoshinobu, Jun
中科院分区：
文献类型：
--
作者：
Koitaya, Takanori;Yamamoto, Susumu;Yoshinobu, Jun
采用常压X射线光电子能谱（AP-XPS）系统研究了CO2在镀铜锌表面的反应。在0.8 mbar CO2和0.4 mbar H-2气体的存在下，未观察到氢化产物;仅在Zn沉积的Cu（111）和Cu（997）表面上形成碳酸盐。299 K时，Zn/Cu（997）上碳酸盐的生成速率明显快于Zn/Cu（111）上，表明台阶位比阶地位对CO2的活化反应更活跃。另一方面，在进料气体中加入水导致在约400 K的样品温度下CO2加氢成甲酸盐。这表明由水的解离吸附产生的羟基是在本反应条件下观察到的CO2氢化的来源。Zn/Cu（997）表面上的反应产物碳酸盐和甲酸盐比Cu（997）表面上的反应产物稳定。特别是，甲酸仍然锌沉积的铜表面高达473 K，这是接近工业Cu-ZnO催化剂的操作温度。因此，Cu表面上的Zn原子的作用之一是稳定由CO2形成的反应中间体。
The reaction of carbon dioxide (CO2) on Zn-deposited copper surfaces was systematically investigated by ambient-pressure X-ray photoelectron spectroscopy (AP-XPS). In the presence of 0.8 mbar CO2 and 0.4 mbar H-2 gases, hydrogenation products are not observed; only carbonate is formed on Zn-deposited Cu(111) and Cu(997) surfaces. The formation rate of carbonate at 299 K is significantly faster on Zn/Cu(997) than that on Zn/Cu(111), indicating step sites are more reactive for CO2 activation than terrace sites. On the other hand, the addition of water in the feed gas leads to hydrogenation of CO2 to formate at sample temperatures around 400 K. This suggests that hydroxyl produced from dissociative adsorption of water is a source for the CO2 hydrogenation observed under the present reaction conditions. The reaction products such as carbonate and formate on the Zn/Cu(997) surface are more stable than those on the bare Cu(997) surface. In particular, formate remains on Zn-deposited Cu surfaces up to 473 K, which is close to the operation temperature of industrial Cu-ZnO catalysts. Therefore, one of the roles of Zn atoms on Cu surfaces is the stabilization of reaction intermediates formed from CO2.