Department of Chemistry, University of California , Berkeley, California 94720, United States.
Department of Materials Science and Engineering, University of California , Berkeley, California 94720, United States.
J Am Chem Soc. 2016 Jul 6;138(26):8207-11. doi: 10.1021/jacs.6b04039. Epub 2016 Jun 23.
Ambient-pressure X-ray photoelectron spectroscopy (APXPS) and high-pressure scanning tunneling microscopy (HPSTM) were used to study the structure and chemistry of model Cu(100) and Cu(111) catalyst surfaces in the adsorption and dissociation of CO2. It was found that the (100) face is more active in dissociating CO2 than the (111) face. Atomic oxygen formed after the dissociation of CO2 poisons the surface by blocking further adsorption of CO2. This "self-poisoning" mechanism explains the need to mix CO into the industrial feed for methanol production from CO2, as it scavenges the chemisorbed O. The HPSTM images show that the (100) surface breaks up into nanoclusters in the presence of CO2 at 20 Torr and above, producing active kink and step sites. If the surface is precovered with atomic oxygen, no such nanoclustering occurs.
常压 X 射线光电子能谱（APXPS）和高压扫描隧道显微镜（HPSTM）被用于研究模型 Cu(100) 和 Cu(111) 催化剂表面在 CO2 吸附和解离过程中的结构和化学性质。结果表明，(100) 面比 (111) 面更活跃，能促使 CO2 解离。CO2 解离后形成的原子氧通过阻止 CO2 的进一步吸附而使表面中毒。这种“自中毒”机制解释了在从 CO2 生产甲醇的工业进料中需要混入 CO 的原因，因为 CO 可以清除化学吸附的 O。HPSTM 图像表明，在 20 托及以上的 CO2 存在下，(100) 表面会分裂成纳米团簇，产生活性扭折和台阶位。如果表面预先覆盖有原子氧，则不会发生这种纳米团簇化。
