A mild post-synthesis oxidative treatment of Pd-In/HOPG bimetallic catalysts as a tool of their surface structure fine tuning

Intermetallic Pd-In particles formation and their deliberate post-synthesis modification by oxidative treatments under carefully controlled conditions have been investigated by the combination of synchrotron radiation-based photoelectron spectroscopy and scanning tunneling microscopy. It is demonstrated that a prolonged contact of Pd-In/HOPG samples with air led to a partial decomposition of intermetallic particles giving rise to the formation of Pd-0 species homogeneously distributed over bulk, surface indium hydroxide and subsurface indium oxide. A mild oxidative treatment (0.25 mbar O-2, 150 degrees C) leads to the indium surface segregation and formation of indium oxide homogeneously distributed over the depth and metallic Pd predominantly localized in the interior. The indium oxide component becomes surface localized upon further temperature increase to 200 degrees C.

Automated summary

This study investigates the formation and modification of intermetallic Pd-In particles under controlled conditions through oxidative treatments. It was found that prolonged exposure to air led to partial decomposition of the particles, with subsequent surface segregation of indium and formation of indium oxide. Further temperature increase resulted in the surface localization of the indium oxide component.