The hydrogenation of carbon dioxide (CO₂) is one of important processes to effectively convert and utilize CO₂, which is also regarded as the key step at the industrial methanol synthesis. Water is likely to play an important role in this process, but it still remains elusive. To systematically understand its influence, here we computationally compare the reaction mechanisms of CO₂ hydrogenation over the stepped Cu(211) surface between in the absence and presence of water based on microkinetic simulations upon density functional theory (DFT) calculations. The effects of water on each hydrogenation step and the whole activity and selectivity are checked and its physical origin is discussed. It is found that the water could kinetically accelerate the hydrogenation on CO₂ to COOH, promoting the reverse water gas shift reaction to produce carbon monoxide (CO). It hardly influences the CO₂ hydrogenation to methanol kinetically. In addition, the too high initial partial pressure of water will thermodynamically inhibit the CO₂ conversion.

中文翻译：

---

在水存在下Cu（211）上二氧化碳加氢的第一性原理微动力学研究

二氧化碳（CO ₂）的氢化是有效转化和利用CO ₂的重要过程之一，这也被认为是工业甲醇合成的关键步骤。水可能在此过程中起重要作用，但仍然难以捉摸。为了系统地了解其影响，在这里我们通过计算比较CO ₂的反应机理基于密度泛函理论（DFT）计算的微动力学模拟，在不存在和存在水之间的阶梯状Cu（211）表面上进行氢化。检查了水对每个氢化步骤的影响以及整个活性和选择性，并讨论了其物理来源。发现水可以在动力学上加速在CO ₂上加氢为COOH，从而促进水煤气的逆反应，从而生成一氧化碳（CO）。它几乎不影响从动力学上将CO ₂加氢成甲醇。另外，水的初始分压太高将在热力学上抑制CO ₂转化。