Enhancing sintering resistance of atomically dispersed catalysts in reducing environments with organic monolayers

Controlling Heterogeneous Catalysis with Organic Monolayers on Metal Oxides

“…46 Recent work suggested that PAs, for example, can be used to functionalize SACs such as Rh 1 / Al 2 O 3 . 47 In that study, the Rh sites did not appear to be significantly blocked by the SAM, as the 1-hexene hydrogenation rates were comparable to those of the unmodified catalysts. However, PA functionalization significantly improved resistance of SACs toward sintering.…”

“…A topic of particular interest is the use of atomically dispersed, or “single atom” catalysts (SACs) . Recent work suggested that PAs, for example, can be used to functionalize SACs such as Rh 1 /Al 2 O 3 . In that study, the Rh sites did not appear to be significantly blocked by the SAM, as the 1-hexene hydrogenation rates were comparable to those of the unmodified catalysts.…”

Investigating deposition sequence during synthesis of Pd/Al2O3 catalysts modified with organic monolayers

“…Thus, one possible reason that the PA-modified catalysts exhibit lower average particle sizes and narrower particle size distributions is that the PAs reduce sintering, which has previously been observed for Au/TiO 2 45 and atomically dispersed Rh/Al 2 O 3 catalysts. 46 However, it is also interesting to note that for 5% Pd/Al 2 O 3 modified with ClMPA, SAM-first deposition resulted in smaller particles than metal-first deposition. Similarly, for 5% Pd/Al 2 O 3 catalysts, different PA modifiers resulted in different average particle sizes ranging from 3.2 nm for 5% Pd/ClMPA/Al 2 O 3 to 2.6 nm for 5% Pd/MPA/Al 2 O 3 .…”

The Simple Synthesis of High Metal Loading Single-Atom Catalysts via Chelate Fixation

“…This method can reliably produce small metal nanoparticles (28,29), as well as isolated single atoms if the metal loading is low enough (30,31). However, at loadings greater than ~0.1 wt%, activation of such catalysts (i.e, through calcination and/or reduction treatments) results in cluster and nanoparticle formation (30,32). One strategy to achieve high single metal atom loadings involves the use of chelating agents that complex with the metal precursor and are then pyrolyzed (sometimes along with other organic components) to produce a carbon material with single metal atoms dispersed throughout.…”