Stabilizing supported atom-precise low-nuclearity platinum cluster catalysts by nanoscale confinement

Abstract

Supported noble metal cluster catalysts provide the advantages of high atom efficiency and size-dependent properties, but their stabilization remains a major challenge for industrial applications. Now we report an approach for the stabilization of nuclearity-controlled platinum nanoclusters with a typical diameter of ~0.7 nm (Pt7−14) confined on CeOx nanoislands on a porous silica support. The clusters were synthesized by the reduction of platinum single atoms on the islands in H2 at 400 °C. Redox cycles led to cluster formation and breakup at hundreds of degrees Celsius, with platinum remaining confined to the respective islands. The clusters maintained their nuclearity and were resistant to sintering in H2 at temperatures of ≤600 °C and atmospheric pressure. Experimental catalyst performance data bolstered by computational results demonstrate that these platinum clusters are more active than mononuclear platinum, also exhibiting higher steady-state activity than larger and smaller platinum clusters for ethylene hydrogenation. Platinum nanoclusters comprising about ten atoms each made by reducing isolated platinum cations in CeOx nests isolated on high-area silica are demonstrated. Two forms of platinum were reversibly interconverted by oxidation/reduction, remaining stably confined to the nests even under severe conditions, in H2 at 600 °C and under atmospheric pressure.