Titanium Doping Induced Anisotropic Geometric and Electronic Modifications Improve Acidic Oxygen Evolution Reaction on RuO2(110) Surface.

Metal doping has garnered attention as a strategy to enhance the oxygen evolution reaction (OER) activity and stability of Ru-oxides. However, the relationship between the surface structure and OER performance remains poorly understood. In this study, we prepared Ti-doped RuO2(110) thin films using arc plasma deposition and investigated how Ti doping affects the near-surface structure and OER properties in an acidic environment. Up to 5 at% doped Ti was uniformly incorporated into the films without disrupting the 2-fold symmetry of the (110) surface. However, TiO2 segregated near the outermost surface at higher doping levels, reducing surface symmetry. Ti doping improved the OER activity and Tafel slope across all doping concentrations, whereas the charge-normalized activity showed that the doping effect included an increase in the surface area. Furthermore, Ti doping markedly suppressed the rise in potential and Ru dissolution during constant-current electrolysis. In-plane X-ray diffraction and total-reflection X-ray absorption fine structure analyses revealed that Ti doping induced anisotropic strain in the RuO2 crystal and altered the electronic structure of Ru. These findings suggest that Ti doping significantly enhances the activity, stability, and corrosion resistance of the RuO2(110) surface, driven by synergistic changes in the surface structure, lattice strain, and electronic structure of RuO2.