Greatly Enhanced Oxygen Reduction Reaction in Anion Exchange Membrane Fuel Cell and Zn‐Air Battery via Hole Inner Edge Reconstruction of 2D Pd Nanomesh

Platinum group metals (PGM) have yet to be the most active catalysts in various sustainable energy reactions. Their high cost, however, has made maximizing the activity and minimizing the dosage become an urgent priority for the practical applications of emerging technologies. Herein, a novel 2D Pd nanomesh structure possessing hole inner reconstructed edges (HIER) with exposed high energy facets and overstretched lattice parameters is fabricated through a facile room-temperature reduction method at gram-scale yields. The HIER enhances the catalytic performance of Pd in electrochemical oxygen reduction reaction (ORR), achieving superior mass activity (MA) of 2.672 A mg_Pd ^-1, which is 27.8 fold and 23.6 fold higher, respectively, than those of the commercial Pt/C (0.096 A mg_Pt ^-1) and Pd/C (0.113 A mg_Pd ^-1) at 0.9 V_RHE. Most significantly, in H₂-air anion exchange membrane fuel cell (AEMFC) and Zn-air battery (ZAB) applications, this unique Pd catalyst delivers a much-outperformed peak power density of 0.86 and 0.22 W cm^-2, respectively, compared with 0.54 and 0.13 W cm^-2 of the commercial Pt/C catalyst, indicating a novel pathway in electrocatalyst designs through HIER engineering.