Atomically Engineered Defect‐Rich Palladium Metallene for High‐Performance Alkaline Oxygen Reduction Electrocatalysis

Abstract

AbstractDefect engineering is a key chemical tool to modulate the electronic structure and reactivity of nanostructured catalysts. Here, it is reported how targeted introduction of defect sites in a 2D palladium metallene nanostructure results in a highly active catalyst for the alkaline oxygen reduction reaction (ORR). A defect‐rich WOx and MoOx modified Pd metallene (denoted: D‐Pd M) is synthesized by a facile and scalable approach. Detailed structural analyses reveal the presence of three distinct atomic‐level defects, that are pores, concave surfaces, and surface‐anchored individual WOx and MoOx sites. Mechanistic studies reveal that these defects result in excellent catalytic ORR activity (half‐wave potential 0.93 V vs. RHE, mass activity 1.3 A mgPd−1 at 0.9 V vs. RHE), outperforming the commercial references Pt/C and Pd/C by factors of ≈7 and ≈4, respectively. The practical usage of the compound is demonstrated by integration into a custom‐built Zn‐air battery. At low D‐Pd M loading (26 µgPd cm−2), the system achieves high specific capacity (809 mAh gZn−1) and shows excellent discharge potential stability. This study therefore provides a blueprint for the molecular design of defect sites in 2D metallene nanostructures for advanced energy technology applications.