Special Chemical Properties of RuOx Nanowires in RuOx/TiO2(110): Dissociation of Water and Hydrogen Production

Recently, there has been a strong interest in understanding the role of mixed-metal oxides in catalysts used for the production of hydrogen through the splitting of water. Here, we investigate the structural and chemical properties of RuOx/TiO2(110) surfaces employing scanning tunneling microscopy, photoemission, and density functional calculations. Ruthenium oxide forms unique wirelike structures on top of TiO2(110) which are very reactive toward water dissociation, being able to cleave O-H bonds at a temperature as low as 200 K The calculated barrier for the dissociation of water on RuO2 nanowires is <0.05 eV. The presence of easily formable O vacancies in the ruthenium oxide nanowires facilitates the dissociation of water. Furthermore, RuOx/TiO2 (110) surfaces are able to catalyze the production of hydrogen through the water-gas shift reaction (H2O + CO -> H-2 + CO2), exhibiting an activity that compares well with the activity found for extended surfaces of copper typically used as benchmarks for studying this reaction.