Synergistic Assistance of Ir Clusters and NiCo 2 O 4 Nanosheets Interfaces in Direct O-O Coupling for High-Efficiency Alkaline Oxygen Evolution.

Adopting noble metals on non-noble metals is an effective strategy to balance the cost and activity of electrocatalysts. Herein, a thorough analysis of the synergistic OER is conducted at the heterogeneous interface formed by Ir clusters and NiCo 2 O 4 based on DFT calculations. Specifically, the electrons spontaneously bring an e g occupancy of interfacial Ir close to unity after the absorbed O, providing more transferable electrons for the conversion of the absorbed O-intermediates. Besides, the diffuse distribution of electrons in the Ir 5 d orbital fills the antibonding orbital after O is absorbed, avoiding the desorption difficulties caused by the stronger Ir-O bonds. The electrons transfer from Ir to Co atoms at the heterogeneous interface and fill the Co 3 d band near the Fermi level, stimulating the interfacial Co to participate in the direct O-O coupling (DOOC) pathway. Experimentally, the ultrathin-modulated NiCo 2 O 4 nanosheets are used to support Ir clusters (Ir cluster -E-NiCo 2 O 4 ) by the electrodeposition method. The as-synthesized Ir cluster -E-NiCo 2 O 4 catalyst achieves a current density of 10 mA cm -2 at an ultralow overpotential of 238 mV and works steadily for 100 h under a high current of 100 mA cm -2 , benefiting from the efficient DOOC pathway during the OER.