Strong electrostatic adsorption of Pt onto SiO 2 partially overcoated Al 2 O 3 -Towards single atom catalysts

• Published in: The Journal of chemical physics Vol. 151; no. 21; p. 214703
• Main Authors: Bo, Zhenyu, McCullough, Lauren R, Dull, Samuel, Ardagh, M Alexander, Wang, Jie, Notestein, Justin
• Format: Journal Article
• Language: English
• Published: United States 07.12.2019
• ISSN: 1089-7690

It is frequently desired to synthesize supported metal catalysts that consist of very small clusters or single atoms. In this work, we combine strong electrostatic adsorption (SEA) of H PtCl and engineered oxide supports to ultimately produce very small Pt clusters, including a large fraction of single Pt atoms. The supports are synthesized by depositing controlled amounts of SiO onto Al O (SiO @Al O ) that has been previously grafted with bulky organic templates. After the templates are removed, the oxide supports are largely negatively charged, like SiO , but have small patches of positively charged Al O , derived from the regions previously covered by the template. The overall point of zero charge of these materials decreases from pH 6.4 for 1 cycle of SiO deposition to a SiO -like <2 for materials with more than 5 cycles of SiO deposition. SEA at pH 4 on templated SiO @Al O deposits from 1 wt. % to 0.05 wt. % Pt as the amount of SiO increases. Pt loadings drop to near zero in the absence of a template. The resulting Pt nanoparticles are generally <1 nm and have dispersion near 100% by CO chemisorption. Finally, CO DRIFTS shows that the CO nanoparticles become increasingly well defined and have a higher percentage of Pt single atoms as the amount of SiO increases on the SiO @Al O particles. Overall, this method of synthesizing patches of charge on a carrier particle appears to be a viable route to creating extremely highly dispersed supported metal catalysts.