The development of efficient catalysts to accelerate the three-phase reaction at the cathode side represents a crucial step in enhancing the performance of lithium-oxygen batteries (LOBs) with high energy density. In this study, NiFe 2 O 4 /CeO 2 composites with an appropriate Ce concentration were prepared as cathode catalysts for LOBs, and the unique micro-flower structure maximally exposed the active sites of the materials. The catalyst cleverly integrates the excellent oxygen evolution reaction (OER) activity of NiFe 2 O 4 and the outstanding oxygen reduction reaction (ORR) activity of CeO 2 . The high concentration of oxygen vacancies and the composite structure synergistically enhanced the charge transfer ability, altered the charge distribution of the active sites, and modulated the electronic structure of the material, thereby achieving an appropriate adsorption energy for oxygen-containing intermediates. Consequently, the composite material displays 343 stable cycles, a round-trip efficiency of 97.8 %, and a discharge specific capacity of 7478 mAh/g. Additionally, it exhibits fast charging and slow discharging capabilities for up to 726 h. This work offers insights into the design of efficient bifunctional cathode catalysts for LOBs.
Interface engineering via the construction of heterojunctions to accelerate electron transfer is an effective strategy for enhancing electrocatalytic activity. This study designed and synthesized a NiFe 2 O 4 /CeO 2 Mott–Schottky (M–S) heterojunction for efficient urea oxidation reaction (UOR), which exhibits exceptional activity with a current density of 50 mA cm −2 at 1.40 V (vs. RHE). Spectroscopic analyses validate the formation of the M–S heterojunction, where a significant work function difference drives spontaneous electron transfer from NiFe 2 O 4 to CeO 2 through Ni–O–Ce bridge, thereby establishing a strong built-in electric field. This interfacial charge rearrangement precisely modulates the electronic structure of the Ni sites, enhancing initial urea adsorption and lowering the d -band center. Such modulation weakens intermediate binding and reduces the energy barrier for the rate-determining CO 2 desorption step. The utility of NiFe 2 O 4 /CeO 2 is demonstrated through reduced energy consumption in hybrid water electrolysis along with improved efficiency and longevity in urea-assisted zinc–air batteries. This study elucidates the effectiveness of M–S heterojunction engineering for developing highly efficient catalysts for advanced energy conversion and storage.
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