Dynamic Structural Evolution of Mn–Au Alloy and MnO_x Nanostructures on Au(111) under Different Atmospheres

Construction of inverse oxide/metal model catalyst with specific chemical composition and interfacial structure is essential for clarifying their structure–performance relationship. This work describes the structural evolution of Mn–Au surface alloy and two-dimensional manganese oxide (MnO_x) islands on Au(111) surface under different treatment conditions. By employing near-ambient pressure scanning tunneling microscopy and X-ray photoelectron spectroscopy, we can obtain four different MnO_x structures. Among them, double-layer square lattice Mn₃O₄(001) and monolayer parallelogram-shaped Mn₃O₄ are prepared by postannealing Mn–Au surface alloy in “oxygen-poor” and “oxygen-rich” regimes, respectively. Annealing the monolayer parallelogram-shaped Mn₃O₄ in vacuum to 700 K produces a double-layer structure consisting of Mn₃O₄ top layer and MnO(111) bottom layer, while double-layer MnO(111) is formed after annealing in vacuum to 800 K. Our study lays the foundation for exploring the catalytic properties of inverse manganese oxide/metal model catalysts.