Optimizing Electro‐Oxidation Kinetics via Constructing Built‐In Electric Field on Pd‐Ni(OH)₂ Heterostructures for Selective Oxidation of Benzylamine to Benzonitrile

Rationally regulating redox properties of electrocatalysts is highly essential to accomplish selective electro-oxidation of benzylamine (BA) to benzonitrile (BN) and concurrently promote hydrogen evolution reaction (HER) at cathode. Herein, a facile built-in electric field (BIEF) engineering strategy to optimize the electrocatalytic kinetics for the BA oxidation reaction (BOR) on Pd-Ni(OH)₂ heterostructures, is presented. Both experimental and theoretical results confirm the construction of BIEF with the direction from α-Ni(OH)₂ nanosheet to Pd nanoparticle at the heterointerface. It is unequivocally found that the creation of BIEF is favorable for not only the generation of electroactive Ni(OH)O species, but also the adsorption and dehydrogenation of BA molecules, achieving significantly promoted BOR kinetics. As expected, the Pd-Ni(OH)₂ catalyst shows excellent electrocatalytic performance toward selectively oxidizing BA to BN, which is further coupled with cathodic H₂ production. The faradaic efficiency (FE) for BN production can approximate to 85% in a two-electrode electrolyzer. In situ Raman spectroscopy and electrochemical measurements disclose that the activity origin for the BOR is dehydronated Ni(OH)O intermediate, clarifying a direct electro-oxidation mechanism over the Pd-Ni(OH)₂ electrode. This work highlights an effective insight into design and synthesis of highly active electrocatalysts for organic upgrading.