Tailoring Metal Nuclearity of Pt/γ‐Al ₂ O ₃ Catalysts: When Molecular Precursors Matter

ABSTRACT Highly dispersed Pt/γ‐Al 2 O 3 catalysts play a tremendous role in heterogeneous catalysis, however, synthesizing materials with well‐defined Pt nuclearity remains a challenge. In this work, we demonstrate how surface organometallic chemistry (SOMC) can be employed to tune cluster size down to single atoms by selecting an appropriate organometallic precursor (MeCpPtMe 3 , tmedaPtMe 2 , or CODPtMe 2 ) at low platinum loading (0.03 Pt.nm −2 ). FTIR and solution NMR analyses indicate that part of the tmedaPtMe 2 and CODPtMe 2 precursors graft through protonolysis with the hydroxyl groups of the γ‐Al 2 O 3 support, while the remaining fraction, along with MeCpPtMe 3 , is deposited via adsorption onto γ‐Al 2 O 3 . Upon calcination, MeCpPtMe 3 produces the highest proportion of platinum single atoms, while CODPtMe 2 generates the lowest among the series. Following reduction, sub‐nanometric clusters (0.6 nm) are formed, significantly smaller than those obtained with a reference catalyst (0.9 nm) prepared by incipient wetness impregnation (IWI) using a conventional Pt(NH 3 ) 4 (NO 3 ) 2 precursor. CO probe adsorption monitored by FTIR reveals distinct electronic properties of the surface metal atoms depending on the chosen metal precursor. Interestingly, an inverse size‐frequency trend is observed compared to the results reported in the literature for larger clusters (> 1 nm). This finding opens new avenues for modulating the catalytic properties of these materials.