Mechanistic Study of Ethanol Decomposition on Co₃O₄(111) and Pd/Co₃O₄(111) Model Catalysts

Abstract In many advanced catalytic materials, different functionalities are coupled through spillover of active species across heterogeneous interfaces. In the present work, we consider the coupling of a C─C bond cleavage functionality of palladium with the self‐cleaning functionality of reducible Co 3 O 4 . On the model catalyst Pd/Co 3 O 4 (111)/Ir(100), we probed the interplay of the two functionalities for the selective decomposition of ethanol. In a systematic study, we compared the decomposition mechanisms of ethanol on Co 3 O 4 (111)/Ir(100) and Pd/Co 3 O 4 (111)/Ir(100) model catalysts using a variety of analytical techniques including synchrotron radiation photoelectron spectroscopy (SRPES), resonant photoemission spectroscopy (RPES), temperature programmed desorption (TPD), and near ambient pressure X‐ray photoelectron spectroscopy (NAP‐XPS). We found that ethanol decomposes via an ethoxy intermediate yielding acetaldehyde on Co 3 O 4 (111)/Ir(100). Remarkably, the spillover of ethanol/ethoxy species on Pd/Co 3 O 4 (111)/Ir(100) results in the selective formation of methane, hydrogen, and CO. Additionally, we observed CO 2 resulting from the oxidative removal of carbonaceous deposits on Pd nanoparticles via spillover of active oxygen species released by Co 3 O 4 (111)/Ir(100) at higher temperatures. The onset of product formation and the product spectrum on both Co 3 O 4 (111)/Ir(100) and Pd/Co 3 O 4 (111)/Ir(100) depend strongly on the oxidation state of Co 3 O 4 . Complete removal of lattice oxygen from Co 3 O 4 (111) results in the deposition of large amounts of carbon.