Anisotropic growth of Pt on Pd nanocube promotes direct synthesis of hydrogen peroxide

As a joint investigation principle using experimental and theoretical approaches, we report that the anisotropic growth of Pt on Pd nanocubes significantly promotes the direct synthesis of hydrogen peroxide (H₂O₂) from hydrogen (H₂) and oxygen (O₂). The superior H₂O₂ productivity of the anisotropic Pd@Pt core@shell nanocrystals results from the enhanced H₂ conversion and the H₂O₂ selectivity compared to Pd and Pt. From the joint investigation, during the anisotropic growth of the Pd@Pt nanocrystals, high-index facets such as (2 1 0) are generated, and they provide numerous active sites for hydrogen dissociation. Notably, even the nano-catalyst is enclosed by Pt shell, the high-index facets are favorable for opening a new route for hydrogen dissolution into the Pd bulk lattices of the Pd@Pt nanocrystals, in which the dissolved hydrogen can react with chemisorbed O₂ over the nanocrystals to form H₂O₂. This mechanism is suggested by a hydrogen temperature programmed reduction (H₂-TPR) analysis, in situ transmission electron microscopy (TEM), and density functional theory (DFT) calculations. This study provides another option to improve the catalytic performance of core@shell nanocrystals via the generation of high-index facets through anisotropic growth of nanocrystals, in addition to the well-known strain and charge transfer effects. We expect that the anisotropic growth approach could be extended to other catalytic reactions.