Synthesis of a planar, multicomponent catalytic surface of Na2CO3/MnO

O-2 adsorption on MnO(100) precovered with sodium (Na) multilayers was investigated by X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Deposition of Na multilayers leads to a first monolayer of oxidic Na followed by metallic Na island growth. XPS results for the oxidation of the metallic Na islands indicate an incomplete oxidation of Na at 125 K. Oxidation at 350 K completely oxidizes the metallic islands producing a mixture of Na2O and Na2O2. Thermal evolution of the oxidation products was examined. After oxidation at 350 K and flashing to 750 K, Na2O and Na2O2 are the primary oxides on MnO(100). After flashing to 850 K, a solid state reaction of Na2O2/Na2O and the MnO(100) substrate forms a NaMnO2-like surface compound which decomposes above 850 K. Oxygen exchange between CO2 and Na oxides is observed. The strong interaction between CO2 and Na oxide islands forms Na2CO3 on MnO(100). Heating the Na2CO3 covered MnO(100) surface to 600 K for 10 min drives oxidic Na in the first monolayer into the MnO subsurface, and produces a surface exposing islands of Na2CO3 on MnO(100).