Abstract The catalytical active phase and reaction mechanism of methanol synthesis by hydrogenation of carbon dioxide on the surface of Cu/ZnO/Al2O3 catalyst become controversial topics in recent years. In this work, density functional theory calculations are employed to explore the possible mechanisms of the CO2 hydrogenation on three possible active phases, namely Zn/Cu interface, ZnO/Cu interface and hydroxylated Zn/Cu surface (i.e., ZnOH/Cu), which may exist in Cu/ZnO/Al2O3 catalyst under realistic conditions. It is more favorable that CO2 activation takes place by the formate pathway rather than the Reverse Water-Gas Shift pathway. Furthermore, the surface hydroxyl group could significantly increase the activity of formate pathway by improving the hydrogenation steps of HCOO to HCOOH and H3CO to H3COH, which are usually deemed as the rate-determining steps. These results suggest that the ZnOH/Cu phase is not only the most stable but also the most active phase for CO2 activation among Zn/Cu, ZnO/Cu and ZnOH/Cu, which could provide more insight into the design of highly efficient catalyst by tuning the surface active phase under operative conditions.

中文翻译：

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对 Cu/ZnO 催化剂上 CO2 加氢催化活性相的机理洞察

摘要 二氧化碳在Cu/ZnO/Al2O3催化剂表面加氢合成甲醇的催化活性相及反应机理近年来成为有争议的话题。在这项工作中，密度泛函理论计算被用来探索 CO2 在三个可能的活性相上加氢的可能机制，即 Zn/Cu 界面、ZnO/Cu 界面和羟基化的 Zn/Cu 表面（即 ZnOH/Cu），其中在实际条件下可能存在于 Cu/ZnO/Al2O3 催化剂中。更有利的是通过甲酸盐途径而不是反向水煤气转换途径发生 CO2 活化。此外，表面羟基可以通过改进 HCOO 到 HCOOH 和 H3CO 到 H3COH 的加氢步骤显着提高甲酸盐途径的活性，这通常被认为是决定速率的步骤。这些结果表明 ZnOH/Cu 相不仅是 Zn/Cu、ZnO/Cu 和 ZnOH/Cu 中 CO2 活化最稳定而且最活跃的相，这可以为高效催化剂的设计提供更多见解。在操作条件下调整表面活性相。