Oxide-supported precious metal nanoparticles are widely used industrial catalysts. Due to expense and rarity, developing synthetic protocols that reduce precious metal nanoparticle size and stabilize dispersed species is essential. Supported atomically dispersed, single precious metal atoms represent the most efficient metal utilization geometry, although debate regarding the catalytic activity of supported single precious atom species has arisen from difficulty in synthesizing homogeneous and stable single atom dispersions, and a lack of site-specific characterization approaches. We propose a catalyst architecture and characterization approach to overcome these limitations, by depositing ∼1 precious metal atom per support particle and characterizing structures by correlating scanning transmission electron microscopy imaging and CO probe molecule infrared spectroscopy. This is demonstrated for Pt supported on anatase TiO. In these structures, isolated Pt atoms, Pt, remain stable through various conditions, and spectroscopic evidence suggests Pt species exist in homogeneous local environments. Comparing Pt to ∼1 nm preoxidized (Pt) and prereduced (Pt) Pt clusters on TiO, we identify unique spectroscopic signatures of CO bound to each site and find CO adsorption energy is ordered: Pt ≪ Pt < Pt. Pt species exhibited a 2-fold greater turnover frequency for CO oxidation than 1 nm Pt clusters but share an identical reaction mechanism. We propose the active catalytic sites are cationic interfacial Pt atoms bonded to TiO and that Pt exhibits optimal reactivity because every atom is exposed for catalysis and forms an interfacial site with TiO. This approach should be generally useful for studying the behavior of supported precious metal atoms.

Nikol Miojevic is a 9th grader at Ithaca High School, in Upstate New York. She is passionate about science, math, engineering and Latin. She currently takes a course on design and drawing for production, where she learns the basics of engineering and uses CAD. Also, she is a member of the BioBuilder club that focuses on genetics. Before starting high school, Nikol was a student at the Elizabeth Ann Clune Montessori School of Ithaca, where she developed a passion for sciences. It was the summer after 8th grade when she participated in the engineering workshop presented here, where she discovered an interest in engineering. Nikol's hobbies are art and karate.