Robust 2 nm-sized gold nanoclusters on Co₃O₄ for CO oxidation

In this study, gold nanoparticles were dispersed on Co₃O₄ nanoplates, forming a specific Au-Co₃O₄ interface. Upon calcination at 300 °C in air, aberration-corrected STEM images evidenced that the gold nanoclusters (NCs) on Co₃O₄{111} were maintained at ca. 2.2 nm, which is similar to the size of the parent Au colloidal particles, demonstrating the stronger metal-support interaction (SMSI) on Co₃O₄{111}. Au/Co₃O₄{111} showed good catalytic activity (a full CO conversion achieved at 80 °C) and durability (over 10 hours) in CO oxidation, which was mainly due to the promotion by the surface oxygen vacancies and intrinsic defects of Co₃O₄{111} for activating O₂ and by Au⁰, Au, and Au⁺ species on the surface of gold NCs for CO activation, as evidenced by Raman and Fourier-transform infrared (FT-IR) spectroscopy analysis. Au/Co₃O₄ catalyzed CO oxidation obeyed the Langmuir-Hinshelwood mechanism at low temperatures.