Lanthanum-Induced Gradient Fields in Asymmetric Heterointerface Catalysts for Enhanced Oxygen Electrocatalysis

Metal-nitrogen-carbon (M-N-C) catalysts display considerable potential as cost-effective alternatives to noble metals in oxygen electrocatalysis. However, uncontrolled atomic migration and random structural rearrangement during pyrolysis often lead to disordered coordination environments and sparse active sites, fundamentally limiting their intrinsic catalytic activities and long-term durability. Herein, a novel strategy is reported for use in directionally regulating atomic migration pathways via the incorporation of a foreign metal (La). By exploiting the differences in the atomic migration priorities via the Kirkendall effect, directional control of atomic diffusion is achieved to fabricate a well-defined asymmetric multiphase heterointerface catalyst (LaN/LaFe-NC). The presence of high-density, structurally well-defined active sites - along with a built-in directional electric field across the heterointerface - substantially enhances the efficiency of interfacial charge transport, thus improving the intrinsic activity and stability in oxygen electrocatalysis. When incorporated into a rechargeable Zn-air battery, LaN/LaFe-NC delivers a high power density of 211 mW cm^-2, with an exceptional cycling stability of >240 h. This study establishes a generalizable atomic-level design strategy for use in engineering robust heterointerface catalysts and offers valuable insights for application in advancing next-generation renewable energy conversion and storage systems.