Understanding the Activity of Single-Atom Catalysis from Frontier Orbitals

The $d$-band center and charge states are often used to analyze the catalytic activity of noble or transition metal surfaces and clusters, but their applicability for single-atom catalysts (SACs) is unsure. This work suggests that the spatial structure and orientation of frontier orbitals which are closest to the Fermi level of SACs play a vital role. Taking adsorption of several molecules and CO oxidization on ${\mathrm{C}}_{3}\mathrm{N}$-supported single-atom Au as examples, we demonstrate that adsorption and catalytic activities are well correlated with the characteristics of frontier orbitals. This work provides an effective guidance for understanding the performance of single-atom catalysts.