Atomic Rare‐Earth Gd‐N‐C Nanosheets with Low f‐d‐p Hybridization Energy for Efficient Oxygen Reduction Reaction

Abstract Developing the new member of transition Metal‐nitrogen‐carbon (M‐N‐C) for oxygen reduction reaction (ORR) is critical to address the issues in 3d‐orbital metal M‐N‐C as noble metal‐free catalyst to achieve affordable fuel cells and metal‐air batteries. Herein, Gd‐N‐C nanosheets are developed by pyrolyzing the self‐polymerized compound of 2, 6‐diaminopyridine initiated by GdCl 3 . The Gd‐N‐C features a unique mixed structure of single GdN 5 moieties and Gd x N y O z atomic clusters, exhibiting excellent ORR performance with the half‐wave potentials of 0.89 and 0.76 V versus RHE in 0.1 M KOH and 0.5 M H 2 SO 4 , respectively, the ORR activity is confirmed by the high‐performance Zn‐air battery and proton exchange membrane fuel cell with a maximum power density of 191 and 370 mW cm −2 as cathodes, respectively. Moreover, the theoretical calculation verifies that the single GdN 5 moiety with specific f‐d hybridization facilitates the interaction with the intermediate OH* to produce the d‐p hybridization, which can significantly reduce the adsorption energy of OH*, while the existence of Gd x N y O z atomic clusters also can enhance the d‐p hybridization effect and effectively promote the ORR. The results confirm the atomic Gd‐N‐C as the new active site for ORR for the first time and extend the library of the M‐N‐C catalysts.