文摘
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 CO<sub>2sub>. It was found that the (100) face is more active in dissociating CO<sub>2sub> than the (111) face. Atomic oxygen formed after the dissociation of CO<sub>2sub> poisons the surface by blocking further adsorption of CO<sub>2sub>. This “self-poisoning” mechanism explains the need to mix CO into the industrial feed for methanol production from CO<sub>2sub>, as it scavenges the chemisorbed O. The HPSTM images show that the (100) surface breaks up into nanoclusters in the presence of CO<sub>2sub> at 20 Torr and above, producing active kink and step sites. If the surface is precovered with atomic oxygen, no such nanoclustering occurs.