Nanotuning via Local Work Function Control: Ethylene Hydrogenation on Supported Pt Nanoclusters

Catalyzed selective hydrogenation of unsaturated hydrocarbons by supported metal clusters is of major importance for industrial applications and has gained significant attention. Prevention of blocking and deactivation of the reaction resulting from carbonaceous coke formation is a major challenge, with alleviation strategies including exploitation of particle size effects, metal alloying and impurity doping. Here, we demonstrate experimentally and theoretically that the activity, selectivity, specificity, and deactivation of size-selected platinum clusters can be controllably tuned by manipulating the local electronic density of the catalyzing Pt cluster via appropriate choice of the support system. We show that along with interfacial particle-to-support bonding effects, electron transfer and charge balance on the supported subnanometer metal clusters, controlling the catalysts' activity, can be tuned by the local work function of the catalysts' support. Control of this materials property was demonstrated through synthesis of ultrathin amorphous silica, a-SiO₂, films on single crystals with differing work functions, Pt(111) or Mo(211), serving as supports for the active subnanometer cluster component. The catalytic control factor introduced here, akin to support doping, allows steering of the chemical catalytic activity and may be used to inhibit undesirable catalyst poisoning and coke formation.