Role of Reconstruction in the Inertness of Gold toward Oxygen

The activation of O_{2} on Au surfaces is a fundamental step for heterogeneous catalysis and surface oxidation. Although Au is widely recognized for its selectivity in various oxidation reactions, its limited ability to dissociate O_{2} remains a challenge for Au-based catalysis. In this Letter, we show that the surface reconstructions that Au(110) and Au(100) display contribute significantly to their inertness. By studying a series of Au surfaces with different surface geometries, we show that in general hexagonal Au surface structures exhibit a high O_{2} dissociation barrier, while rectangular or square surfaces show a significantly lower barrier. Thus, the reconstruction of the Au(110) and Au(100) surfaces to quasihexagonal structures slows O_{2} dissociation by many orders of magnitude, and Au would likely oxidize quickly under ambient conditions if these surfaces did not reconstruct. This provides new understanding as to why Au is so inert toward O_{2} and suggests that creating surfaces with square or rectangular structures may significantly improve catalytic activity for oxidation reactions on Au.