Dimerization Induced Deprotonation of Water on RuO2(110).
RuO2 has proven to be indispensable as a co-catalyst in numerous systems designed for photocatalytic water splitting. In this study, we have carried out a detailed mechanistic study of water behavior on the most stable RuO2 face, RuO2(110), by employing variable-temperature scanning tunneling microscopy and density functional theory calculations. We show that water monomers adsorb molecularly on Ru sites, become mobile above 238 K, diffuse along the Ru rows, and form water dimers. The onset for dimer diffusion is observed at ∼277 K, indicating a significantly higher diffusion barrier than that for monomers. More importantly, we find that water dimers deprotonate readily to form Ru-bound H3O2 and bridging OH species. The observed behavior is compared and contrasted with that observed for water on isostructural rutile TiO2(110).
†Fundamental and Computational Sciences Directorate, ‡Environmental Molecular Sciences Laboratory, and §Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
Rentao
R
Mu
†Fundamental and Computational Sciences Directorate, ‡Environmental Molecular Sciences Laboratory, and §Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
David C
DC
Cantu
†Fundamental and Computational Sciences Directorate, ‡Environmental Molecular Sciences Laboratory, and §Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
Xiao
X
Lin
†Fundamental and Computational Sciences Directorate, ‡Environmental Molecular Sciences Laboratory, and §Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
Vassiliki-Alexandra
VA
Glezakou
†Fundamental and Computational Sciences Directorate, ‡Environmental Molecular Sciences Laboratory, and §Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
Zhitao
Z
Wang
†Fundamental and Computational Sciences Directorate, ‡Environmental Molecular Sciences Laboratory, and §Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
Igor
I
Lyubinetsky
†Fundamental and Computational Sciences Directorate, ‡Environmental Molecular Sciences Laboratory, and §Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
Roger
R
Rousseau
†Fundamental and Computational Sciences Directorate, ‡Environmental Molecular Sciences Laboratory, and §Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
Zdenek
Z
Dohnálek
adsorption; density functional theory; diffusion; scanning tunneling microscopy; water splitting