A balancing act: manipulating reactivity of shape-controlled metal nanocatalysts through bimetallic architecture

Manipulating the electronic structure of metal nanocrystals is one way of altering their catalytic activities. This ability is demonstrated here by introducing a Au interior to shape-controlled Pd nanocrystals, producing core@ shell Au@ Pd nanoparticles with varying shell thicknesses. As revealed by X-ray photoelectron spectroscopy, the electronic structure of the Pd shell depends on its thickness. These core@ shell nanocrystals were used to catalyze two model reactions: selective hydrogenation of 2-hexyne and oxidation of formic acid, where different reactivities were found also as a function of shell thickness. The comparison of particles with varying bimetallic architecture but identical geometric features provides insight into how electronic regulation in a catalytic reaction can be achieved. It is concluded that a balance in binding interaction between the molecular substrate and catalyst surface is necessary to design an efficient catalyst and can be achieved with shape-controlled core@ shell nanocrystals.