Interstitial Cobalt in Pt Shell of Pd@Pt Mesoporous Core–Shell Nanospheres with Strong d–d Orbital Hybridization for Enhanced Electrocatalytic Ammonia Oxidation

Abstract

Abstract Ammonia oxidation reaction (AOR) is critical for efficient ammonia utilization as a hydrogen carrier, yet state‐of‐the‐art Pt‐based catalysts suffer significant activity loss due to strong * NO x species ( * NO, * NO 2 ) adsorption. Herein, Pd@Pt mesoporous core‐shell nanospheres with interstitial Co in Pt shell (Pd@Pt‐Co MCSN) are demonstrated as an excellent AOR electrocatalyst, which achieves a mass activity of 293.6 A g −1 at 0.7 V versus RHE, 4.8‐fold higher than commercial Pt/C. The interstitial Co dopant tunes the d‐d orbital hybridization state, optimizes the Pt d‐band center position, and facilitates electron transfer from Co to Pt, which effectively weakens the adsorption of toxic * NO x and lowers the energy barrier for N‐N coupling. When integrated into a Zn‐NH 3 battery, the catalyst enables efficient NH 3 ‐to‐H 2 conversion with a Faradaic efficiency of 96.8% and stable operation for 30 hours at 12 mA cm −2 . The work may provide a new design concept to develop advanced electrocatalysts for AOR.