Interfacial Reactions of Tetraphenylporphyrin with Cobalt‐Oxide Thin Films.

We have studied the adsorption and interfacial reactions of 2H‐tetraphenylporphyrin (2HTPP) with cobalt‐terminated Co3O4(111) and oxygen‐terminated CoO(111) thin films using synchrotron‐radiation X‐ray photoelectron spectroscopy. Already at 275 K, we find evidence for the formation of a metalated species, most likely CoTPP, on both surfaces. The degree of self‐metalation increases with temperature on both surfaces until 475 K, where the metalation is almost complete. At 575 K the porphyrin coverage decreases drastically on the reducible cobalt‐terminated Co3O4(111) surface, while higher temperatures are needed on the non‐reducible oxygen‐terminated CoO(111). The low temperature self‐metalation is similar to that observed on MgO(100) surfaces, but drastically different from that observed on TiO2(110), where no self‐metalation is observed at room temperature. [ABSTRACT FROM AUTHOR]