Ketjen Black Selectively Anchoring Pd Nanocrystals on Nitrogen-Doped Graphene Based Aerogel for Robust Ethanol Oxidation

Searching and designing high-quality support materials is a strategy for rationally designing electrocatalysts for the ethanol oxidation reaction (EOR). In this work, the ketjen black (KB) embedded with nitrogen-doped graphene based aerogel (NG) anchoring palladium nanocrystals (Pd/KB@NG) was prepared through a one-step hydrothermal method. As a catalyst for EOR, Pd/KB@NG-2 (the mass ratio of graphene oxide and KB is 2:1) has significantly improved electrocatalytic performance compared with commercial Pd/C and other counterparts. The Pd nanocrystals were selectively anchored on the interface composed of KB and NG owing to the spatial confinement effect. Despite the higher Pd content (13.4 wt %), Pd nanocrystals (Pd NCs) are densely and uniformly dispersed between KB and NG on account of the anchoring and confinement effects of KB. The spatial confinement effect can also prevent the loss of the precious metal Pd, thereby improving the electrocatalytic activity and stability of the samples. Moreover, the electron-donating property of KB induces the electrons to flow from KB to Pd NCs, which enhances the electronic metal–support interaction, thus optimizing the adsorption behavior of toxic intermediate CH 3 CO ads and improving the electrocatalytic performance of the catalysts. In addition, the embeddedness of the highly conductive KB between NG not only endows fast channels to transfer interelectrons from the supports to the active metal but also generates the large number of pore structures, thereby creating the siphon effect and accelerating the mass transfer process during the process of EOR. Based on the spatial confinement effect, this work not only provides a perspective for the rational design of highly active catalysts but also opens an avenue to a generation of Pd-based catalysts for DEFCs and beyond.