Pinpointing Nanogold’s Catalytic Sites

Why trap and sequester CO₂ for long-term storage if the greenhouse gas can be converted to valuable carbon compounds? Driven by that thinking, researchers have identified numerous conversion strategies, including electrochemically reducing CO₂ to CO, which is a feedstock used to make synthetic fuels and other products. Several metals show moderate promise as electroreduction catalysts. But without a detailed understanding of the relationship between a catalyst’s structure and function, it’s difficult to tailor catalysts and improve their performance. For nanoparticulate gold, Brown University’s Andrew A. Peterson, Shouheng Sun, and coworkers have deduced a key piece of that relationship. The team reports that among various-sized gold particles, 8-nm gold particles are exceptionally good CO₂ reduction catalysts (J. Am. Chem. Soc. 2013, DOI: 10.1021/ja409445p). And as a result of their quantum mechanical analysis, the researchers know why: Edge sites between adjacent crystal faces stabilize key carbon-based reduction intermediates, while corner sites drive competing reactions. Crystal growth energetics cause 8-nm particles to exhibit an optimum ratio of those sites, the team reports.