Catalytic\nSynergy between Pd Nanoclusters and Ligand-Functionalized\nLayered Silicates for Improved Formic Acid Dehydrogenation

The\nsynthesis and stabilization of Pd nanoclusters on a support,\nas well as simultaneously achieving optimal catalytic activity, remain\nchallenging tasks. Functionalizing the support surface with specific\nligands offers a promising solution, but it often requires carefully\nbalancing trade-offs between the reaction yield and catalyst stability.\nHere, we used two different ligands (propylamine and propylthiol)\nto functionalize the layered silicate’s interlayer surface\nfor Pd nanocluster synthesis and stabilization. For dehydrogenating\nformic acid, Pd nanoclusters on aminopropyl groups achieved a catalytic\nactivity ∼27-fold higher than that of thiopropyl groups at\n70 °C. Our density functional calculations compared the adsorption\nenergetics and bonding characteristics of single Pd atoms and Pd<sub>13</sub> nanoclusters on amino- and thio-functionalized silicate\nsurfaces. Pd–N bonds were predicted to be weaker with minimal\ncovalency, while Pd–S bonds exhibit greater covalency due to\nhigher 4d–3p hybridization, resulting in better stability.\nHowever, Pd<sub>13</sub> clusters undergo severe structural deformation\non thiol-functionalized surfaces, resulting in a smaller overall surface\narea and diminished catalytic stability.