The significance of catalytic active interfacial sites in metal supported on metal oxide systems has been well established in prototypical CO oxidation reactions. Here, we investigate the role of water molecules in the CO oxidation reaction using Pt nanoparticles (Pt NPs) supported by a two-dimensional (2D) cerium oxide thin-film. The 2D model CeO₂ thin films were fabricated using the e-beam evaporation technique and a monolayer of Pt nanoparticles deposited on CeO₂ thin films by the Langmuir-Blodgett (LB) method. The well-defined reaction conditions, such as humid and dry conditions, were achieved using an ultra-high vacuum (UHV) batch chamber. Interestingly, we found a strong metal-support interaction (SMSI) in the Pt/CeO₂ catalyst under dry reaction conditions, which was increased further by the presence of water molecules. However, water had a detrimental effect on a Pt thin-film model catalyst under humid reaction conditions. By altering the partial pressures of water molecules and CO, the reaction mechanism was established under humid conditions. The current results demonstrate that hydroxyl intermediates from water molecules provide an alternative pathway to the Pt/CeO₂ catalyst, resulting in increased overall turnover rates. These findings shed light on the synergistic interplay of water and metal-oxide interfaces.

在典型的 CO 氧化反应中，金属氧化物系统上负载的金属中催化活性界面位点的重要性已得到充分证实。在这里，我们使用由二维 (2D) 氧化铈薄膜支持的 Pt 纳米颗粒 (Pt NPs) 研究水分子在 CO 氧化反应中的作用。二维模型CeO ₂薄膜是使用电子束蒸发技术和Langmuir-Blodgett (LB) 方法沉积在CeO ₂薄膜上的单层Pt纳米粒子制造的。使用超高真空 (UHV) 批处理室实现了明确定义的反应条件，例如潮湿和干燥条件。_{有趣的是，我们在 Pt/CeO 2}中发现了强烈的金属-载体相互作用 (SMSI)干燥反应条件下的催化剂，由于水分子的存在而进一步增加。然而，在潮湿反应条件下，水对 Pt 薄膜模型催化剂具有不利影响。通过改变水分子和CO的分压，建立了潮湿条件下的反应机理。目前的结果表明，来自水分子的羟基中间体为 Pt/CeO ₂催化剂提供了替代途径，从而提高了总周转率。这些发现揭示了水和金属氧化物界面的协同相互作用。