Stabilizing Single-Atom and Small-Domain Platinum via Combining Organometallic Chemisorption and Atomic Layer Deposition

Oxide-supported single-atom Pt materials are prepared by combining surface organometallic chemisorption with atomic layer deposition (ALD). Here Pt is supported as a discrete monatomic “pincer” complex, stabilized by an atomic layer deposition (ALD) derived oxide overcoat, and then calcined at 400 °C under O2. ALD-derived Al2O3, TiO2, and ZnO overlayers are effective in suppressing Pt sintering and significantly stabilizing single Pt atoms. Furthermore, this procedure decreases the overall Pt nuclearity (∼1 nm average particle diameter) versus bare Pt (∼3.8 nm average diameter), as assayed by aberration corrected HAADF-STEM. The TiO2 and ZnO overcoats are significantly more effective at stabilizing single-atom Pt species and decreasing the overall Pt nuclearity than Al2O3 overcoats. Vibrational spectroscopy of adsorbed CO also shows that oxidized Pt species commonly thought to be single Pt atoms are inactive for catalytic oxidation of adsorbed CO. CO chemisorption measurements show site blockage by the ALD overcoats.