Gadolinium-Induced Valence Structure Engineering for Enhanced Oxygen Electrocatalysis

摘要

Rare earth doped materials with unique electronic ground state configurations are considered emerging alternatives to conventional Pt/C for the oxygen reduction reaction (ORR). Herein, gadolinium (Gd)-induced valence structure engineering is, for the first, time investigated for enhanced oxygen electrocatalysis. The Gd2O3-Co heterostructure loaded on N-doped graphene (Gd2O3-Co/NG) is constructed as the target catalyst via a facile sol-gel assisted strategy. This synthetic strategy allows Gd2O3-Co nanoparticles to distribute uniformly on an N-graphene surface and form intimate Gd2O3/Co interface sites. Upon the introduction of Gd2O3, the ORR activity of Gd2O3-Co/NG is significantly increased compared with Co/NG, where the half-wave potential (E-1/2) of Gd2O3-Co/NG is 100 mV more positive than that of Co/NG and even close to commercial Pt/C. The density functional theory calculation and spectroscopic analysis demonstrate that, owing to intrinsic charge redistribution at the engineered interface of Gd2O3/Co, the coupled Gd2O3-Co can break the OOH*-OH* scaling relation and result in a good balance of OOH* and OH* binding on Gd2O3-Co surface. For practical application, a rechargeable Zn-air battery employing Gd2O3-Co/NG as an air-cathode achieves a large power density and excellent charge-discharge cycle stability.