In Situ Observations of CO2 Activation on the PdIn(111) Alloy Surface at Ambient Pressures

초록

The CO2 activation process has been investigated on the palladium-indium (PdIn) (111) alloy surface using ambient pressure scanning tunneling microscopy (AP-STM) and synchrotron-based X-ray photoelectron spectroscopy (AP-XPS). Pd and In atoms diffuse onto the topmost layer after annealing at 840 K, which adopts intermetallic PdIn alloy geometries in an ultrahigh vacuum. AP-STM reveals that interfacial Pd-InO x nanostructures are created on the alloy surface by dissociative CO2 adsorption under CO2(g) environments even at 300 K. Synchrotron-based AP-XPS measurements support the idea that the observed CO2 activation induces InO x segregation onto the PdIn(111) surface by dissociated atomic oxygen from CO2. After all, CO2 gas molecules simultaneously adsorb onto the oxygen-terminated sites of the Pd-InO x nanoclusters to produce carbonate species. Our in situ observations indicate that the restructuring metastable PdIn(111) alloy surface may provide active sites for efficient CO2 activation, contributing to the rational catalyst design toward sustainable CO2 utilizations.

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