Band engineering in heterostructure catalysts to achieve High-Performance Lithium-Oxygen batteries.

The upper shift of the d-band level of Fe active sites was realized by regulating electronic structure of NiFe 2 O 4 /MoS 2 heterostructure, fundamentally improving the electrocatalytic performance of NiFe 2 O 4 /MoS 2. [Display omitted] The electronic structure of cathode catalysts dominates the electrochemistry reaction kinetics in lithium-oxygen batteries. However, conventional catalysts perform inferior intrinsic activity due to the low d-band level of the active sites makes it difficult to bond with the reaction intermediates, which results in poor electrochemical performance of lithium-oxygen batteries. Herein, NiFe 2 O 4 /MoS 2 heterostructures are elaborately constructed to reach an electronic state balance for the active sites, which realizes the upper shift of the d-band level and enhanced adsorption of intermediates. Density functional theory calculation suggests that the d-band center of Fe active sites on the heterostructure moves toward the Fermi level, demonstrating the heterointerface engineering endows Fe active sites with high d-band level by the transfer and balance of electron. As a proof of concept, lithium-oxygen battery catalyzed by NiFe 2 O 4 /MoS 2 exhibits a large specific capacity of 21526 mA h g−1 and an extended cycle performance for 268 cycles. Moreover, NiFe 2 O 4 /MoS 2 with strong adsorption to intermediates promotes the uniform growth of discharge products, which is favor of the reversible decomposition during cycling. This work presents the energy band regulation of the active sites in heterostructure catalysts has great feasibility for enhancing catalytic activities. [ABSTRACT FROM AUTHOR]