Ordered hydroxyls on Ca<sub>3</sub>Ru<sub>2</sub>O<sub>7</sub>(001).
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28634335.
- Also identified by DOI 10.1038/s41467-017-00066-w and PMC identifier 5478604.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
As complex ternary perovskite-type oxides are increasingly used in solid oxide fuel cells, electrolysis and catalysis, it is desirable to obtain a better understanding of their surface chemical properties. Here we report a pronounced ordering of hydroxyls on the cleaved (001) surface of the Ruddlesden-Popper perovskite Ca<sub>3</sub>Ru<sub>2</sub>O<sub>7</sub> upon water adsorption at 105 K and subsequent annealing to room temperature. Density functional theory calculations predict the dissociative adsorption of a single water molecule (E <sub>ads</sub> = 1.64 eV), forming an (OH)<sub>ads</sub> group adsorbed in a Ca-Ca bridge site, with an H transferred to a neighboring surface oxygen atom, O<sub>surf</sub>. Scanning tunneling microscopy images show a pronounced ordering of the hydroxyls with (2 × 1), c(2 × 6), (1 × 3), and (1 × 1) periodicity. The present work demonstrates the importance of octahedral rotation and tilt in perovskites, for influencing surface reactivity, which here induces the ordering of the observed OH overlayers.As ternary perovskite-type oxides are increasingly used in fuel cells and catalysis, greater understanding of their surface chemical properties is required. Here the authors report a pronounced ordering of hydroxyls on the cleaved (001) surface of Ca<sub>3</sub>Ru<sub>2</sub>O<sub>7</sub> perovskite induced by O-octahedral rotation and tilt.