Fig. 1: Morphological study of the Ru/TiO₂ catalysts.

a Elemental mapping of Ru/Ti/O in the fresh Ru/TiO₂ catalyst. b HAADF-STEM image of the Ru/TiO₂ catalyst pretreated at 600 °C (Ru/TiO₂-600 sample) with the metal size distribution. c HRTEM image of the Ru/TiO₂-600 catalyst.