Continuing our efforts to elucidate the working principle of Au/ZnO catalysts for the synthesis of green methanol from CO₂ and H₂, we present a systematic X-ray photoelectron spectroscopy (XPS) study on the interaction of bimetallic Zn/Au(111) surfaces with O₂ and NO₂ (O*), on the oxidation of Zn atoms in these bimetallic model systems and on the formation ZnO_x species or thin films on these surfaces. At room temperature, we find little adsorption and essentially no oxidation of Zn atoms alloyed into the Au(111) near-surface region upon exposure to O₂ or NO_2, and accordingly no Zn de-alloying. LT interaction of O₂ or NO₂ with Zn submonolayer structures leads to higher oxygen and / or NO₂ coverages. Formation of oxidic ZnO_x species / structures occurs, however, only after annealing above RT, both after O₂ and NO₂ exposure. This involves partial conversion of adsorbed species into ZnO_x. ZnO/Au(111) thin films, especially thicker ones, can be efficiently prepared by reactive deposition of Zn in O₂ or NO₂, followed by annealing. RT deposition in NO₂ gives a higher fraction of (incompletely) oxidized ZnO_x compared to O₂, Fully oxidized ZnO is formed after subsequent annealing, upon thermally activated conversion of adsorbed O_ad/OH species into oxidic oxygen and dissolution of remaining metallic Zn atoms into the Au bulk. Overall, the study provides detailed insights into the formation of ZnO_x thin films on Au(111).

继续努力阐明Au / ZnO催化剂从CO ₂和H ₂合成绿色甲醇的工作原理，我们对双金属Zn / Au（111）的相互作用进行了系统的X射线光电子能谱（XPS）研究。这些双金属模型系统中Zn原子的氧化作用以及在这些表面上形成的ZnO _x物质或薄膜上具有O ₂和NO ₂（O *）的表面。在室温下，我们发现几乎没有吸附，而暴露于O ₂或NO _2时，合金化成Au（111）近表面区域的Zn原子基本上没有氧化_，因此没有Zn脱合金。O ₂或NO的LT相互作用具有Zn亚单层结构的₂导致较高的氧和/或NO ₂覆盖率。然而，仅在RT以上退火之后，才在O ₂和NO ₂暴露下发生氧化ZnO _x物种/结构的形成。这涉及将吸附物质部分转化为ZnO _x。通过在O ₂或NO _2中反应性沉积Zn ，然后进行退火，可以有效地制备ZnO / Au（111）薄膜，尤其是较厚的薄膜。与O ₂相比，NO _2中的RT沉积产生了更高比例的（不完全）氧化的ZnO _x在随后的退火之后，将吸附的O _ad / OH物质热活化转化为氧化性氧并将剩余的金属Zn原子溶解到Au块中后，会形成完全氧化的ZnO 。总体而言，该研究为在Au（111）上形成ZnO _x薄膜提供了详细的见识。